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12 pages, 3163 KiB

Open AccessArticle

Effect of Processing Parameters on Wear Properties of Hybrid AA1050/Al₂O₃/TiO₂ Composites

by Yuanfei Gao, Mohammad Heydari Vini, Saeed Daneshmand, Ameer A. Alameri, Omrane Benjeddou and Raed H. C. Alfilh

Crystals 2023, 13(2), 335; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst13020335 - 16 Feb 2023

Cited by 2 | Viewed by 1236

Abstract

In this study, hybrid AA1050/Al₂O₃/TiO₂ composites have been produced via combined liquid casting and powder metallurgy techniques. Degassing was utilized to improve the wettability of molten aluminum alloys, and then successful bonding was generated between aluminum matrix and [...] Read more.

In this study, hybrid AA1050/Al₂O₃/TiO₂ composites have been produced via combined liquid casting and powder metallurgy techniques. Degassing was utilized to improve the wettability of molten aluminum alloys, and then successful bonding was generated between aluminum matrix and reinforcement particles during the powder metallurgy technique. As the base matrix and reinforcements, AA1050 alloy, Al₂O₃ and TiO₂ particles were taken, respectively. Then, content values of 5Wt.% of Al₂O₃ in the mesh size of 20 μm and 2.5 and 5 wt. % of TiO₂ particles with mesh size of 5μm were added to the AA1050 matrix. For each composite sample, ceramic particles were warmed to 600°C in order to improve wettability and distribution. An identical scattering of subdivisions was observed through aluminum (as matrix) in the microstructural study. To measure the wear resistance, the mechanism of rotary wear test was used. The achieved results illustrated that the fabrication of hybrid composites is an ideal approach to improve the wear resistance of Al-based composites. By increasing of TiO₂ Wt.% up to 5% for all composite samples, the wear rate improved to less than half of the monolithic Al alloy value for each composite sample. Full article

(This article belongs to the Special Issue Feature Papers on "Hybrid and Composite Crystalline Materials" 2021-2022)

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15 pages, 6408 KiB

Open AccessArticle

Molecular Dynamics Study of Interdiffusion for Cubic and Hexagonal SiC/Al Interfaces

by Masoud Tahani, Eligiusz Postek and Tomasz Sadowski

Crystals 2023, 13(1), 46; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst13010046 - 27 Dec 2022

Cited by 6 | Viewed by 2063

Abstract

The mechanical properties of the SiC/Al interface are crucial in estimating the overall strength of this ceramic-metal composite. The present work investigates the interdiffusion at the SiC/Al interface using molecular dynamics simulations. One cubic and one hexagonal SiC with a higher probability of [...] Read more.

The mechanical properties of the SiC/Al interface are crucial in estimating the overall strength of this ceramic-metal composite. The present work investigates the interdiffusion at the SiC/Al interface using molecular dynamics simulations. One cubic and one hexagonal SiC with a higher probability of orientations in contact with Al are examined as two samples of metal-matrix nanocomposites with whisker and particulate reinforcements. These reinforcements with the Si- and C-terminated surfaces of the SiC/Al interfaces are also studied. The average main and cross-interdiffusion coefficients are evaluated using a single diffusion couple for each system. The effect of temperature and annealing time are analysed on the self- and interdiffusion coefficients. It is found that the diffusion of Al in SiC is similar in cubic and hexagonal SiC and as expected, the interdiffusion coefficient increases as the temperature and annealing time increase. The model after diffusion can be used to evaluate the overall mechanical properties of the interface region in future studies. Full article

(This article belongs to the Special Issue Feature Papers on "Hybrid and Composite Crystalline Materials" 2021-2022)

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13 pages, 4372 KiB

Open AccessArticle

Synthesis, Crystal Structure and Optical Properties of 3,5-Dihydroxyphenyl-5-(dimethylamino)naphthalene-1-sulfonate as a Fluorescence Sensor for Fluoride Ion Detection

by Siraprapa Khunarj, Woradorn Saijaroensakul, Wilailak Marom, Kittipong Chainok, Tanwawan Duangthongyou, Bussaba Pinchaipat and Boontana Wannalerse

Crystals 2022, 12(12), 1836; https://doi.org/10.3390/cryst12121836 - 15 Dec 2022

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Abstract

3,5-Dihydroxyphenyl-5-(dimethylamino)naphthalene-1-sulfonate, also referred to as sensor R1, was synthesized and characterized by ¹H- and ¹³C-NMR, IR, HRMS, and single-crystal X-ray diffraction. Connections in the packing crystal structure of sensor R1 occur through hydrogen bonding interactions. However, no π-π stacking interactions between [...] Read more.

3,5-Dihydroxyphenyl-5-(dimethylamino)naphthalene-1-sulfonate, also referred to as sensor R1, was synthesized and characterized by ¹H- and ¹³C-NMR, IR, HRMS, and single-crystal X-ray diffraction. Connections in the packing crystal structure of sensor R1 occur through hydrogen bonding interactions. However, no π-π stacking interactions between molecules of sensor R1 were observed. Addition of fluoride ion to a solution of sensor R1 resulted in the appearance of a new absorption band at 310 nm, which corresponded to the deprotonated species, and quenching of the peak at an emission wavelength of 562 nm. For the addition of other anions, there was a slight decrease in corresponding peaks in the UV-visible and emission spectra of sensor R1. According to the ¹H-NMR study, the aromatic proton resonances of sensor R1 shifted upfield when adding fluoride ion. Analysis of the solutions prepared using Job’s method revealed that the complexation ratio of the complex formed between sensor R1 and fluoride ion was 1:1. The Stern−Volmer quenching constant (K_sv) between sensor R1 and fluoride ion was characterized as 7157 M⁻¹. Full article

(This article belongs to the Special Issue Feature Papers on "Hybrid and Composite Crystalline Materials" 2021-2022)

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9 pages, 3344 KiB

Open AccessArticle

Layered Hybrid iron Fluorides

by Teng Li and Philip Lightfoot

Crystals 2022, 12(10), 1443; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12101443 - 13 Oct 2022

Viewed by 1225

Abstract

The first examples of layered hybrid iron fluorides are reported. In the reactions carried out, the chain compound (H₂pipz)FeF₅·H₂O always occurs as the major phase, with the layered compounds, (H₂pipz)₃Fe₄ [...] Read more.

The first examples of layered hybrid iron fluorides are reported. In the reactions carried out, the chain compound (H₂pipz)FeF₅·H₂O always occurs as the major phase, with the layered compounds, (H₂pipz)₃Fe₄F1₈·2H₂O and (H₂pipz)₂Fe₃F₁₃·H₂O, being isolated from some reactions as major impurities. The latter two compounds feature two-dimensional sheets of corner-and edge-shared FeIIIF₆ octahedra, resulting in two distinct layer architectures. The compound (H₂pipz)FeF₅·H₂O, isolated as the major phase, crystallises with a one-dimensional structure exhibiting zig-zag [FeF₅]_∞ chains. This work opens up the potential for a much wider family of layered hybrid transition-metal fluorides. Full article

(This article belongs to the Special Issue Feature Papers on "Hybrid and Composite Crystalline Materials" 2021-2022)

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11 pages, 5788 KiB

Open AccessArticle

Mechanical and Wear Properties of Al/TiC Composites Fabricated via Combined Compo-Casting and APB Process

by Weining Wang, Mohammad Heydari Vini and Saeed Daneshmand

Crystals 2022, 12(10), 1440; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12101440 - 12 Oct 2022

Cited by 10 | Viewed by 1119

Abstract

One of the popular techniques to fabricate metal matrix composites is the compo-casting process. The un-uniform spreading of reinforced subdivisions (particles) inside the metallic matrix and the lack of desirable mechanical properties of the final produced composites due to the low bonding strength [...] Read more.

One of the popular techniques to fabricate metal matrix composites is the compo-casting process. The un-uniform spreading of reinforced subdivisions (particles) inside the metallic matrix and the lack of desirable mechanical properties of the final produced composites due to the low bonding strength among the metal matrix and reinforcement particles are the main challenges in this process. The warm accumulative press bonding (APB) technique was utilized as the supplementary technique to improve the mechanical and microstructural evolution of casted Al/TiC composite bars to remove these difficulties. So, using the tensile test, average Vickers micro hardness test, wear test and scanning electron microscopy (SEM), the microstructure evolution and mechanical properties of these composites have been considered vs. various WAPB steps. The SEM morphology of samples revealed that big titanium carbide clusters are broken and make a uniform distribution of titanium carbide particles at higher APB steps. It was shown that the cumulative forming steps of the APB process improved the mechanical properties of composites. In general, combining the compo-casting and APB process would result in making Al/TiC composites with high uniformity and good mechanical and microstructural properties. Full article

(This article belongs to the Special Issue Feature Papers on "Hybrid and Composite Crystalline Materials" 2021-2022)

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13 pages, 1726 KiB

Open AccessArticle

A New Insight into the Role of Silicate-Type Binders on the Crushing Strength of Alumina Foams

by Fernando de Almeida Costa Oliveira, Stéphane Pommier, Jorge Cruz Fernandes and Diamantino Dias

Crystals 2022, 12(10), 1394; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12101394 - 02 Oct 2022

Viewed by 1323

Abstract

Semi-closed cell macroporous alumina foams with relative densities ranging from 0.26 to 0.35 have been produced by the well-established replication method based on the coating of a polyurethane (PU) template foam by a ceramic slurry, followed by burnout of the PU template, and [...] Read more.

Semi-closed cell macroporous alumina foams with relative densities ranging from 0.26 to 0.35 have been produced by the well-established replication method based on the coating of a polyurethane (PU) template foam by a ceramic slurry, followed by burnout of the PU template, and sintering of the ceramic skeleton. Collapse of the three-dimensional structure upon the volatilisation of the PU sponge can only be prevented using appropriate binders. Scarce data are available on the slurry formulations of commercial alumina foams. The aim of this study was to investigate the influence of silicate-type binders, namely kaolin and bentonite additives, on the crushing strength of alumina foams. The highest crushing strength of around 10 MPa was observed at a porosity of 66 ± 2%. The open-cell model is inadequate to fit the crushing strength data of such semi-closed cell type structures. Both microscopic and macroscopic flaws resulting from the foam processing method contribute to the wide scatter of the strength, thereby explaining the Weibull modulus ranging from 4 to 7. Both flaw populations require further improvement to maximise the crushing strength of these foams with high potential for the design of structured catalyst carriers and molten aluminium filters. Full article

(This article belongs to the Special Issue Feature Papers on "Hybrid and Composite Crystalline Materials" 2021-2022)

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7 pages, 2043 KiB

Open AccessArticle

Pyrolyzed Bacterial Cellulose as the Backbone of the Cathode Catalyst-CoFe₂O₄ for the Li-O₂ Battery

by Xiangjun Wang, Yongqing Chi, Peng Wu and Wen Liu

Crystals 2022, 12(8), 1165; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12081165 - 19 Aug 2022

Cited by 1 | Viewed by 1469

Abstract

In this paper, CoFe₂O₄@pyrolyzed bacterial cellulose (CFO@PBC) nanocomposites were synthesized by a hydrothermal process and an in situ composite technique as the cathode for rechargeable Li-O₂ batteries (LOB). CoFe₂O₄@Ketjenblack (CFO@KB) were prepared in the [...] Read more.

In this paper, CoFe₂O₄@pyrolyzed bacterial cellulose (CFO@PBC) nanocomposites were synthesized by a hydrothermal process and an in situ composite technique as the cathode for rechargeable Li-O₂ batteries (LOB). CoFe₂O₄@Ketjenblack (CFO@KB) were prepared in the same way as the comparison. The as-prepared materials were characterized by SEM, XRD, and BET. The LOB with CFO@PBC-3 showed a maximum initial discharge capacity of 2660 mAh g⁻¹ (electrode) at the current density of 100 mAg⁻¹, while the mass ratio of CoFe₂O₄ and pyrolyzed bacterial cellulose was 3. The cyclic voltammetry of the CFO@PBC nanocomposite electrodes was investigated at 0.1 mVs⁻¹ in the voltage window of 2.0–4.5 V. With the limited capacity of 640 mAh g⁻¹ (electrode), the CFO@PBC-3 electrode showed the best cycle stability and higher cutoff voltage of discharging. The pyrolyzed bacterial cellulose, as the fibrous 3D backbone in CFO@PBC nanocomposite electrodes, produced better results than the CFO@KB. Full article

(This article belongs to the Special Issue Feature Papers on "Hybrid and Composite Crystalline Materials" 2021-2022)

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13 pages, 5016 KiB

Open AccessArticle

Improvement of Mechanical Properties and Condensation Behavior for Alkali-Activated Materials by Sodium Silicate

by Mingjing Li, Guodong Huang, Yi Cui, Bo Wang, Shuwei Zhang, Qi Wang and Jiacheng Feng

Crystals 2022, 12(8), 1018; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12081018 - 22 Jul 2022

Cited by 2 | Viewed by 1142

Abstract

To further enhance the compressive strength of alkali-activated materials and reveal their condensation behavior, the reactivity of alkali-activated slag materials was enhanced through the addition of different kinds and proportions of sodium silicate. The mechanical properties of the specimens were observed regularly and [...] Read more.

To further enhance the compressive strength of alkali-activated materials and reveal their condensation behavior, the reactivity of alkali-activated slag materials was enhanced through the addition of different kinds and proportions of sodium silicate. The mechanical properties of the specimens were observed regularly and the condensation behavior was further analyzed. The results showed that both solid and liquid sodium silicate could significantly improve the compressive strength. The maximum increase in compressive strength was 123.7%, while the initial and final setting times were significantly shortened to 9 min. When solid sodium silicate content increased from 5% to 15%, the compressive strength first increased to 34.6 MPa and then decreased to 28.6 MPa, indicating that 10% was the optimum solid sodium silicate content. The large amount of crystallized solid sodium silicate in the specimen led to the decrease in mechanical properties. When liquid sodium silicate content increased from 5% to 15%, the compressive strength first increased to 52.8 MPa and then tended to be stable, implying that 10% was the optimum content. This shows that its reinforcement effect has a maximum limit. The activation effect of liquid sodium silicate was better than that of solid. Full article

(This article belongs to the Special Issue Feature Papers on "Hybrid and Composite Crystalline Materials" 2021-2022)

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12 pages, 8561 KiB

Open AccessFeature PaperArticle

Stable CsPbBr₃ Nanocrystals—Decorated Nanoporous Gold for Optoelectronic Applications

by Jessica Satta, Andrea Pinna, Giorgio Pia, Luca Pilia, Carlo Maria Carbonaro, Daniele Chiriu, Luigi Stagi, Qader Abdulqader Abdullah and Pier Carlo Ricci

Crystals 2022, 12(6), 863; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12060863 - 18 Jun 2022

Cited by 1 | Viewed by 1967

Abstract

Halide perovskite colloidal nanocrystals have recently gained much attention thanks to their superior stability compared with their bulk counterpart and to their unique optical properties. In this paper, two systems combining nanocrystals and nanoporous gold are studied to create an optimal metal semiconductor [...] Read more.

Halide perovskite colloidal nanocrystals have recently gained much attention thanks to their superior stability compared with their bulk counterpart and to their unique optical properties. In this paper, two systems combining nanocrystals and nanoporous gold are studied to create an optimal metal semiconductor heterojunction that can be used in photocatalysis and photovoltaic devices. The perovskite degradation phenomenon is observed when the nanoporous gold powder is mixed into the hexane suspension of nanocrystals, while the charge separation efficiency is increased by synthesizing the nanocrystals directly onto the gold porous structure. The analysis of the structural and optical properties evidences an energy transfer efficiency of 47%, along with the high structural stability of the hybrid system. Full article

(This article belongs to the Special Issue Feature Papers on "Hybrid and Composite Crystalline Materials" 2021-2022)

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13 pages, 2032 KiB

Open AccessArticle

Compressive Strength Enhancement in Early Age Acid Activated Mortars: Mechanical Properties and Analysis

by Guodong Huang, Dawei Li, Yi Cui, Jiacheng Feng, Qi Gao, Tianyang Lu, Yuting Zhang and Jielei Zhu

Crystals 2022, 12(6), 804; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12060804 - 07 Jun 2022

Cited by 4 | Viewed by 1439

Abstract

To increase the hydration reaction rate and the amount of hydration products, different types and proportions of acids were mixed into mortars. The effects of the acid type and content on the early compressive strength of cement-based materials and the strengthening mechanism were [...] Read more.

To increase the hydration reaction rate and the amount of hydration products, different types and proportions of acids were mixed into mortars. The effects of the acid type and content on the early compressive strength of cement-based materials and the strengthening mechanism were assessed via X-ray diffraction and Fourier-transform infrared spectrum analyses. The addition of acetic acid or hydrochloric acid significantly increased the compressive strength of mortars at 1 d and 3 d, and slightly increased it at 28 d. With increasing acetic acid content, the strengthening effect increased first and then decreased with the best content at 4%. With increasing hydrochloric acid content, the strengthening effect decreased gradually with the best content at 2%. Full article

(This article belongs to the Special Issue Feature Papers on "Hybrid and Composite Crystalline Materials" 2021-2022)

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8 pages, 1907 KiB

Open AccessArticle

Structure Tuning of Hafnium Metal–Organic Frameworks through a Mixed Solvent Approach

by Yanhong Ma and Xin Zhang

Crystals 2022, 12(6), 785; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12060785 - 29 May 2022

Cited by 1 | Viewed by 1938

Abstract

The recent development of water-stable metal–organic frameworks (MOFs) has significantly broadened the application scope of this emerging type of porous material. Structure tuning of hafnium MOFs is less studied compared with zirconium MOFs. In this work, we report the synthesis of a mesoporous [...] Read more.

The recent development of water-stable metal–organic frameworks (MOFs) has significantly broadened the application scope of this emerging type of porous material. Structure tuning of hafnium MOFs is less studied compared with zirconium MOFs. In this work, we report the synthesis of a mesoporous hafnium MOF, csq-MOF-1, through finely tuning the solvent mixture ratio. The successful synthesis of csq-MOF-1 also relies on the linker flexibility as linker bending and a symmetry decrease were observed in this framework as compared to its structural isomer NPF-300 (Hf). The mesoporous feature and permanent porosity were determined by the N₂ adsorption at 77 K. Such a hierarchical pore feature is expected to enable a variety of applications through encapsulation of large functional molecules. The synthetic strategy of utilizing a mixed solvent and flexible linker is expected to inspire the development of new hafnium MOFs with diverse topological structures. Full article

(This article belongs to the Special Issue Feature Papers on "Hybrid and Composite Crystalline Materials" 2021-2022)

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16 pages, 5044 KiB

Open AccessArticle

Mechanisms of Selected Anionic Dye Removal by Clinoptilolite

by Xisen Wang, Jessica Baker, Kristen Carlson and Zhaohui Li

Crystals 2022, 12(5), 727; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12050727 - 19 May 2022

Cited by 4 | Viewed by 1422

Abstract

The extensive use of color dyes in modern society has resulted in serious concerns of water contamination. Many organic dyes bear charges; thus, materials of opposite charges have been tested for sorptive removal. However, the results from several studies also showed that anionic [...] Read more.

The extensive use of color dyes in modern society has resulted in serious concerns of water contamination. Many organic dyes bear charges; thus, materials of opposite charges have been tested for sorptive removal. However, the results from several studies also showed that anionic dyes methyl orange (MO) and alizarin red S (ARS) could be removed from water using minerals of negative charges, but the mechanisms were not addressed. In this study, negatively charged clinoptilolite was tested for its removal of anionic dyes MO and ARS from water under different physico-chemical conditions and to investigate the mechanism of Mo and ARS removal. The sorption capacities were 166 and 92 mmol/kg for MO and ARS, respectively, confirming the uptake of anionic dyes on negatively charged framework silicates. The influence of solution pH and ionic strength on MO removal was minimal, indicating the strong affinity of anionic dyes for clinoptilolite in comparison to other inorganic species. It was speculated that the N in the dimethyl group may bear a partial positive charge, which may have a net electrostatic attraction to the negatively charged mineral surfaces for MO sorption. For ARS, sorption may involve hydrogen bonding formation between the dye and the clinoptilolite. Moreover, under the experimental conditions, the MO molecules form dimers in solution via dimeric π-π interactions. Thus, the sorption of the dimers or aggregation of the MO monomers and dimers on clinoptilolite surface was attributed to additional MO removal, as suggested by molecular dynamic simulations. The speculation was supported by FTIR analyses and molecular dynamic simulations. As such, negatively charged Earth materials may be used as sorbents for the removal of certain anionic dyes via sorption, a new perspective for the innovative use of Earth materials. Full article

(This article belongs to the Special Issue Feature Papers on "Hybrid and Composite Crystalline Materials" 2021-2022)

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13 pages, 1228 KiB

Open AccessArticle

The Effect of Slag on the Mechanical Properties of Coralline-Activated Materials and the Formation and Transformation of Mineral Crystals

by Guodong Huang, Jielei Zhu, Yuting Zhang, Dawei Li, Bo Wang, Mengrong Li, Lina Jin and Jinghai Gong

Crystals 2022, 12(4), 470; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12040470 - 28 Mar 2022

Cited by 4 | Viewed by 1453

Abstract

In this study, coralline-activated materials were prepared using ball-milled coral powder as cementitious material and coral sand as fine aggregate. XRF (X-ray fluorescence) and chemical dissolution tests were carried out to determine the content and reactivity of various elements in coral powder. The [...] Read more.

In this study, coralline-activated materials were prepared using ball-milled coral powder as cementitious material and coral sand as fine aggregate. XRF (X-ray fluorescence) and chemical dissolution tests were carried out to determine the content and reactivity of various elements in coral powder. The compressive strength of the developed composites was evaluated at different ages, and the formation and transformation of mineral crystals in coralline-activated samples were further analyzed by XRD (X-ray diffractometer). The results show that the calcium content in coral powder was as high as 89.5% (loss on ignition). However, only 56% of the active calcium could participate in the polymerization reaction. The silicon and aluminum content was too low, and the slag addition could improve the deficiency of silicon and aluminum in coral powder. With the increase in slag content (from 0% to 50%), the compressive strength of the composites increases significantly. Nevertheless, the enhancement is not pronounced when the slag content exceeds 50%. The increase in slag amount can stimulate the transformation of calcium minerals, e.g., aragonite and calcite, into hydrated calcium silicate and calcium aluminosilicate gels, which significantly enhances the resulting compressive strength. Full article

(This article belongs to the Special Issue Feature Papers on "Hybrid and Composite Crystalline Materials" 2021-2022)

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17 pages, 3673 KiB

Open AccessArticle

Counter Anion Effects on the Formation and Structural Transformations of Mo(vi)-Hydrazone Coordination Assemblies: Salts, Solvates, Co-Crystals, and Neutral Complexes

by Mirna Mandarić, Biserka Prugovečki, Ivana Kekez, Danijela Musija, Jelena Parlov Vuković, Marina Cindrić and Višnja Vrdoljak

Crystals 2022, 12(4), 443; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12040443 - 22 Mar 2022

Cited by 1 | Viewed by 1909

Abstract

Complex salts [1H]X and [1H](XA)_0.5·2MeOH, and co-crystals [1H]X·0.5VA (X = chloride or bromide, XA = chloranilate or bromanilate, VA = o-vanillin azine), comprising [MoO₂(HL)(MeOH)]⁺ ([1H]⁺) cation (H₂L = 3-methoxysalicylaldehyde isonicotinoyl hydrazone), were [...] Read more.

Complex salts [1H]X and [1H](XA)_0.5·2MeOH, and co-crystals [1H]X·0.5VA (X = chloride or bromide, XA = chloranilate or bromanilate, VA = o-vanillin azine), comprising [MoO₂(HL)(MeOH)]⁺ ([1H]⁺) cation (H₂L = 3-methoxysalicylaldehyde isonicotinoyl hydrazone), were prepared either by solution-based synthesis or by mechanochemical synthesis. Whereas [1H]X salts were extremely sensitive to humidity, their stability could be reinforced by the azine incorporation into the complex network. Solvent-mediated transformations of [1H]X led to methanol co-ligand replacement and afforded complexes [MoO₂(HL)X] (2Cl·MeOH, 2Cl, and 2Br·0.5MeCN). However, solvates [1H](XA)_0.5·2MeOH, under the same conditions, gave stable complexes [1H](XA)_0.5 in which methanol remained coordinated. The differences in the assembly’s behavior were attributed to the packing arrangements, the relative orientation of cations and anions, and interactions between them. Polymorph [MoO₂(L)(MeOH)] (1), not attainable by other routes, was the only product when compounds [MoO₂(HL)X] were treated with a weak base at low temperatures. Tetranuclear [MoO₂(L)]₄ and polynuclear [MoO₂(L)]_n (2) supramolecular isomers, concomitantly crystallized when the reaction was conducted solvothermally. All of the complexes were characterized using X-ray diffraction methods (SCXRD and PXRD), spectroscopic methods (ATR-IR and solution-state and solid-state MAS NMR), and elemental and thermal analyses. The cytotoxicity of the different types of compounds against THP-1 and HepG2 cells was also evaluated. Full article

(This article belongs to the Special Issue Feature Papers on "Hybrid and Composite Crystalline Materials" 2021-2022)

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7 pages, 841 KiB

Open AccessArticle

Appearance of Supersonic Stoneley Waves in Auxetics

by Sergey V. Kuznetsov

Crystals 2022, 12(3), 430; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12030430 - 19 Mar 2022

Viewed by 1409

Abstract

It is shown that in auxetic materials (materials with negative Poisson’s ratio), supersonic Stoneley waves travelling without attenuation with a velocity equal to or exceeding maximum bulk wave velocity, may exist. Analytical expressions for the relation between negative Poisson’s ratio and Young’s moduli [...] Read more.

It is shown that in auxetic materials (materials with negative Poisson’s ratio), supersonic Stoneley waves travelling without attenuation with a velocity equal to or exceeding maximum bulk wave velocity, may exist. Analytical expressions for the relation between negative Poisson’s ratio and Young’s moduli of the contacting isotropic media ensuring the condition of propagation for supersonic Stoneley waves, are derived by solving a secular equation for Stoneley waves. Full article

(This article belongs to the Special Issue Feature Papers on "Hybrid and Composite Crystalline Materials" 2021-2022)

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8 pages, 1866 KiB

Open AccessArticle

Halogen Bonding and CO-Ligand Blue-Shift in Hybrid Organic—Organometallic Cocrystals [CpFe(CO)₂X] (C₂I₄) (X = Cl, Br)

by Yury Torubaev, Ivan Skabitskiy, Sergey Shapovalov, Olga Tikhonova and Anna Popova

Crystals 2022, 12(3), 412; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12030412 - 17 Mar 2022

Cited by 1 | Viewed by 1342

Abstract

This work is focused on the complex interplay of geometry of I⋯X halogen bonds (HaB) and intermolecular interaction energy in two isomorphic cocrystals [CpFe(CO)₂X] (C₂I₄) (X = Cl (1), Br (2)). Their IR-spectroscopic [...] Read more.

This work is focused on the complex interplay of geometry of I⋯X halogen bonds (HaB) and intermolecular interaction energy in two isomorphic cocrystals [CpFe(CO)₂X] (C₂I₄) (X = Cl (1), Br (2)). Their IR-spectroscopic measurements in solid state and solution demonstrate the blue-shift of CO vibration bands, resulting from I⋯X HaB. The reluctance of their iodide congener [CpFe(CO)₂I] to form the expected cocrystal [CpFe(CO)₂I] (C₂I₄) is discussed in terms of different molecular electrostatic potential (MEP) of the surface of iodide ligands, as compared with chloride and bromide, which dictate a different angular geometry of HaB around the metal-I and metal-Br/Cl HaB acceptors. This study also suggests C₂I₄ as a reliable HaB donor coformer for metal-halide HaB acceptors in the crystal engineering of hybrid metal–organic systems. Full article

(This article belongs to the Special Issue Feature Papers on "Hybrid and Composite Crystalline Materials" 2021-2022)

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16 pages, 3483 KiB

Open AccessArticle

Self-Diffusion of Individual Adsorbed Water Molecules at Rutile (110) and Anatase (101) TiO₂ Interfaces from Molecular Dynamics

by Stephanie J. Boyd, Dáire O’Carroll, Yogeshwaran Krishnan, Run Long and Niall J. English

Crystals 2022, 12(3), 398; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12030398 - 15 Mar 2022

Cited by 2 | Viewed by 2282

Abstract

The distribution of individual water molecules’ self-diffusivities in adsorbed layers at TiO₂ surfaces anatase (101) and rutile (110) have been determined at 300 K for inner and outer adsorbed layers, via classical molecular-dynamics methods. The layered-water structure has been identified and classified [...] Read more.

The distribution of individual water molecules’ self-diffusivities in adsorbed layers at TiO₂ surfaces anatase (101) and rutile (110) have been determined at 300 K for inner and outer adsorbed layers, via classical molecular-dynamics methods. The layered-water structure has been identified and classified in layers making use of local order parameters, which proved to be an equally valid method of “self-ordering” molecules in layers. Significant distinctness was observed between anatase and rutile in disturbing these molecular distributions, more specifically in the adsorbed outer layer. Anatase (101) presented significantly higher values of self-diffusivity, presumably due to its “corrugated” structure that allows more hydrogen bonding interaction with adsorbed molecules beyond the first hydration layer. On the contrary, rutile (110) has adsorbed water molecules more securely “trapped” in the region between Ob atoms, resulting in less mobile adsorbed layers. Full article

(This article belongs to the Special Issue Feature Papers on "Hybrid and Composite Crystalline Materials" 2021-2022)

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13 pages, 3903 KiB

Open AccessArticle

Basaltic Glass Fibers from Industrial Wastes: A Laboratory-Scale Technical Feasibility Study

by Simone Tiozzo, Stefano Sanchetti, Martiniano Picicco, Maurizio Zanforlin, Edoardo Bemporad, Annalisa Zacco and Laura E. Depero

Crystals 2022, 12(3), 359; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12030359 - 08 Mar 2022

Viewed by 1804

Abstract

This study demonstrated the physical–chemical and technical feasibility of recycling EAF slag granulated by rapid cooling with gas to produce continuous glass fibers with a basalt-like composition. To adjust the chemical composition, a silica fume-based secondary raw material was used, together with other [...] Read more.

This study demonstrated the physical–chemical and technical feasibility of recycling EAF slag granulated by rapid cooling with gas to produce continuous glass fibers with a basalt-like composition. To adjust the chemical composition, a silica fume-based secondary raw material was used, together with other additives. Different compositions were tested: 50% EAF slag and 50% silica fume (sample C1); 40% EAF slag, 50% silica fume and 10% Na₂O (sample C2); 40% EAF slag, 50% silica fume, 5% Na₂O and 5% K₂O (sample C3); 20% EAF slag, 57% silica fume, 10% Na₂O and 13% alkali earth oxides (sample C4); 26% EAF slag, 35% silica fume, 7% CaO and 12% Na₂O (sample C5); 26% EAF slag, 35% silica fume, 4% CaO and 15% Na₂O (sample C6). The last composition allowed obtaining fibers up to 5–6 m long, with a diameter between 60 and 180 µm. The process involved using a refractory material crucible with a calibrated bottom orifice as a single nozzle bushing. The optimal temperature range for fiber forming was between 1115 and 1125 °C, with a linear drawing speed of about 2 m/s. Preliminary mechanical tests were performed. Based on these results, potential further recycling applications of granulated EAF slag in the production of basalt-like glass for noncontinuous fiber production for mechanical reinforcement or for thermal–acoustic insulation can also be foreseen. Full article

(This article belongs to the Special Issue Feature Papers on "Hybrid and Composite Crystalline Materials" 2021-2022)

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16 pages, 1471 KiB

Open AccessArticle

Modifying HKUST-1 Crystals for Selective Ethane Adsorption Using Ionic Liquids as Synthesis Media

by Gregory S. Deyko, Lev M. Glukhov, Vera I. Isaeva, Vladimir V. Chernyshev, Vadim V. Vergun, Danil A. Archipov, Gennady I. Kapustin, Olga P. Tkachenko, Vera D. Nissenbaum and Leonid M. Kustov

Crystals 2022, 12(2), 279; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12020279 - 18 Feb 2022

Cited by 6 | Viewed by 2448

Abstract

Novel adsorbents for methane and ethane based on HKUST-1 metal-organic framework were synthesized by microwave (MW) assisted technique using ionic liquids (ILs) as synthesis media. It was found that the MW synthesis time remarkably impacts both the product yield and the physico-chemical characteristics [...] Read more.

Novel adsorbents for methane and ethane based on HKUST-1 metal-organic framework were synthesized by microwave (MW) assisted technique using ionic liquids (ILs) as synthesis media. It was found that the MW synthesis time remarkably impacts both the product yield and the physico-chemical characteristics of the produced HKUST-1 material. The crystalline phase purity, crystallite size/dispersion and textural properties of the synthesized HKUST-1 matrices determine their performance in methane and ethane adsorption. Therefore, the HKUST-1 material produced in MW fields for 3 min only shows the highest phase purity and the largest surface area (BET) and porosity, along with a rather small crystallite size (below ~300 nm), demonstrating high methane and ethane adsorption capacity in the pressure range 1–30 atm. Full article

(This article belongs to the Special Issue Feature Papers on "Hybrid and Composite Crystalline Materials" 2021-2022)

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11 pages, 1865 KiB

Open AccessArticle

Biogenic Synthesis of AgNPs Using Aqueous Bark Extract of Aesculus indica for Antioxidant and Antimicrobial Applications

by Muhammad Riaz, Amrina Suleman, Pervaiz Ahmad, Mayeen Uddin Khandaker, Amal Alqahtani, David A. Bradley and Muhammad Qayyum Khan

Crystals 2022, 12(2), 252; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12020252 - 12 Feb 2022

Cited by 8 | Viewed by 2140

Abstract

Nanotechnology has received a lot of attention from the scientific community because of the greater surface-to-volume ratio of nanomaterials, which phenomenally increases their efficacy in practical applications. Among the various synthesis techniques, the biogenic or green synthesis of nanomaterials shows advantages over other [...] Read more.

Nanotechnology has received a lot of attention from the scientific community because of the greater surface-to-volume ratio of nanomaterials, which phenomenally increases their efficacy in practical applications. Among the various synthesis techniques, the biogenic or green synthesis of nanomaterials shows advantages over other techniques such as physical, chemical, etc. This study reports the biogenic synthesis of silver nanoparticles (AgNPs) using aqueous bark extract of Aesculus indica. The as-synthesized NPs were characterized by UV–visible, FT-IR, XRD, and SEM, and then tested for their antioxidant and antimicrobial potency. We have identified phenols, flavonoids, tannins, saponins, and carbohydrates in the bark extract of A. indica. The extract-loaded-AgNPs showed the highest inhibition for Staphylococcus aureus (28.0 mm), Pseudomonas aeruginosa (17.66 mm), Escherichia coli (14.33 mm), Acetobacter serratia (14.00 mm), and Klebsiella pneumoniae (12.33 mm). The methanolic bark extract inhibited S. aureus (24.33 mm), P. aeruginosa (10.66 mm), E. coli (11.33 mm), A. serratia (9.66 mm), and K. pneumoniae (11.66 mm). Aqueous bark extract inhibited S. aureus (22.33 mm), P. aeruginosa (8.33 mm), E. coli (9.33 mm), A. serratiaa (8.33 mm), and K. pneumoniae (9.66 mm). Its aqueous extract showed the highest antioxidant potency; IC₅₀ (0.175 µg/mL) followed by the methanolic extract; IC₅₀ (0.210 µg/mL) and extract-loaded nanoparticles; IC₅₀ (0.901 µg/mL). Our findings provide meaningful interest for antioxidant, anti-microbial applications of, and AgNPs synthesis by, aqueous bark extract of A. indica. Full article

(This article belongs to the Special Issue Feature Papers on "Hybrid and Composite Crystalline Materials" 2021-2022)

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13 pages, 2772 KiB

Open AccessArticle

Investigation of the Biological Applications of Biosynthesized Nickel Oxide Nanoparticles Mediated by Buxus wallichiana Extract

by Salah Ud Din, Hina Iqbal, Sirajul Haq, Pervaiz Ahmad, Mayeen Uddin Khandaker, Hosam O. Elansary, Fatemah F. Al-Harbi, Shaimaa A. M. Abdelmohsen and Tarek K. Zin El-Abedin

Crystals 2022, 12(2), 146; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12020146 - 20 Jan 2022

Cited by 8 | Viewed by 2370

Abstract

The preparation of nickel oxide nanoparticles (NiO NPs) was carried out using an environmentally friendly and novel green synthetic strategy that included the use of Buxus wallichiana leaf extract as a reducing agent. Energy-dispersive X-ray (EDX), Fourier-transform infrared spectroscopy (FTIR), diffuse reflectance spectroscopy [...] Read more.

The preparation of nickel oxide nanoparticles (NiO NPs) was carried out using an environmentally friendly and novel green synthetic strategy that included the use of Buxus wallichiana leaf extract as a reducing agent. Energy-dispersive X-ray (EDX), Fourier-transform infrared spectroscopy (FTIR), diffuse reflectance spectroscopy (DRS), X-ray diffraction (XRD), scanning electron microscope (SEM), and thermogravimetric analysis (TGA) techniques were used to characterize the resulting NiO NPs. At various concentrations, NiO NPs were tested for their percentage scavenging activity against the ABTS (2,2′-azinobis-(3-ethylbenzothiazoline-6-sulphonic acid) free radical, with an IC50 value of 234.84 g/L. Furthermore, the bactericidal activity of NiO NPs was studied by the agar well diffusion method against two Gram-positive bacterial strains (B. licheniformis and B. subtilis) and two Gram-negative bacterial strains (E. coli and K. pneumoniae). Full article

(This article belongs to the Special Issue Feature Papers on "Hybrid and Composite Crystalline Materials" 2021-2022)

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12 pages, 3189 KiB

Open AccessArticle

The Design and Optimization of an Anti-Reflection Coating and an Intermediate Reflective Layer to Enhance Tandem Solar Cell Photons Capture

by Hassan Sayed, Z. S. Matar, M. Al-Dossari, A. F. Amin, N. S. Abd El-Gawaad and Arafa H. Aly

Crystals 2022, 12(1), 57; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12010057 - 31 Dec 2021

Cited by 17 | Viewed by 2819

Abstract

We have theoretically demonstrated an efficient way to improve the optical properties of an anti-reflection coating (ARC) and an intermediate reflective layer (IRL) to enhance tandem solar cell efficiency by localizing the incident photons’ energy on a suitable sub-cell. The optimum designed ARC [...] Read more.

We have theoretically demonstrated an efficient way to improve the optical properties of an anti-reflection coating (ARC) and an intermediate reflective layer (IRL) to enhance tandem solar cell efficiency by localizing the incident photons’ energy on a suitable sub-cell. The optimum designed ARC from a one-dimensional ternary photonic crystal, consisting of a layer of silicon oxynitride (

S i O N

), was immersed between two layers of (SiO₂); thicknesses were chosen to be 98 nm, 48 nm, and 8 nm, respectively. The numerical results show the interesting transmission properties of the anti-reflection coating on the viable and near IR spectrum. The IRL was designed from one-dimensional binary photonic crystals and the constituent materials are Bi₄Ge₃O₁₂ and μc-SiO_x: H with refractive indexes was 2.05, and 2.8, respectively. The numbers of periods were set to 10. Thicknesses: d₁ = 62 nm and d₂ = 40 nm created a photonic bandgap (PBG) in the range of [420 nm: 540 nm]. By increasing the second material thickness to 55 nm, and 73 nm, the PBG shifted to longer wavelengths: [520 nm: 630 nm], and [620 nm: 730 nm], respectively. Thus, by stacking the three remaining structures, the PBG widened and extended from 400 nm to 730 nm. The current theoretical and simulation methods are based on the fundamentals of the transfer matrix method and finite difference time domain method. Full article

(This article belongs to the Special Issue Feature Papers on "Hybrid and Composite Crystalline Materials" 2021-2022)

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17 pages, 4159 KiB

Open AccessArticle

2,3-Dihydroquinazolin-4(1H)-one as a New Class of Anti-Leishmanial Agents: A Combined Experimental and Computational Study

by Muhammad Sarfraz, Chenxi Wang, Nargis Sultana, Humna Ellahi, Muhammad Fayyaz ur Rehman, Muhammad Jameel, Shahzaib Akhter, Fariha Kanwal, Muhammad Ilyas Tariq and Song Xue

Crystals 2022, 12(1), 44; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12010044 - 29 Dec 2021

Cited by 2 | Viewed by 2150

Abstract

Leishmaniasis is a neglected parasitic disease caused by various Leishmania species. The discovery of new protozoa drugs makes it easier to treat the disease; but, conventional clinical issues like drug resistance, cumulative toxicity, and target selectivity are also getting attention. So, there is [...] Read more.

Leishmaniasis is a neglected parasitic disease caused by various Leishmania species. The discovery of new protozoa drugs makes it easier to treat the disease; but, conventional clinical issues like drug resistance, cumulative toxicity, and target selectivity are also getting attention. So, there is always a need for new therapeutics to treat Leishmaniasis. Here, we have reported 2,3-dihydroquinazolin-4(1H)-one derivative as a new class of anti-leishmanial agents. Two derivatives, 3a (6,8-dinitro-2,2-disubstituted-2,3-dihydroquinazolin-4(1H)-ones) and 3b (2-(4-chloro-3-nitro-phenyl)-2-methyl-6,8-dinitro-2,3-dihydro-1H-quinazolin-4-one) were prepared that show promising in silico anti-leishmanial activities. Molecular docking was performed against the Leishmanial key proteins including Pyridoxal Kinase and Trypanothione Reductase. The stability of the ligand-protein complexes was further studied by 100 ns MD simulations and MM/PBSA calculations for both compounds. 3b has been shown to be a better anti-leishmanial candidate. In vitro studies also agree with the in-silico results where IC₅₀ for 3a and 3b was 1.61 and 0.05 µg/mL, respectively. Full article

(This article belongs to the Special Issue Feature Papers on "Hybrid and Composite Crystalline Materials" 2021-2022)

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15 pages, 3004 KiB

Open AccessArticle

Detection of Reproductive Hormones in Females by Using 1D Photonic Crystal-Based Simple Reconfigurable Biosensing Design

by Arafa H. Aly, S. K. Awasthi, A. M. Mohamed, Z. S. Matar, M. A. Mohaseb, M. Al-Dossari, M. T. Tammam, Zaky A. Zaky, A. F. Amin and Walied Sabra

Crystals 2021, 11(12), 1533; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11121533 - 09 Dec 2021

Cited by 39 | Viewed by 3536

Abstract

In this manuscript, we have explored the photonic biosensing application of the 1D photonic crystal (PhC) (AB)^NCDC(AB)^N, which is capable of detecting reproductive progesterone and estradiol hormones of different concentration levels in blood samples [...] Read more.

In this manuscript, we have explored the photonic biosensing application of the 1D photonic crystal (PhC) (AB)^NCDC(AB)^N, which is capable of detecting reproductive progesterone and estradiol hormones of different concentration levels in blood samples of females. The proposed structure is composed of an air cavity surrounded by two buffer layers of material MgF₂, which is sandwiched between two identical 1D sub PhCs (AB)^N. Both sub PhCs are made up of alternate layers of materials, SiO₂ and Si, of period 5. MATLAB software has been used to obtain transmission characteristics of the structure corresponding TE wave, only with the help of the transfer matrix method. The mainstay of this research is focused on the dependence of the intensity and position of the defect mode inside the photonic bandgap with respect to reproductive hormone concentrations in blood samples, change in the thickness of the cavity region and change in angle of incidence corresponding to TE wave only. The proposed design shows high sensitivity of 98.92 nm/nmol/L and 96.58 nm/nmol/L when the cavity of a thickness of 340 nm is loaded with progesterone and estradiol hormones of concentrations of 80 nmol/L and 11 nmol/L, respectively, at an incident angle of 20°. Apart from sensitivity, other parameters such as quality factor and figure of merit have also been computed to gain deep insight about the sensing capabilities of the proposed design. These findings may pave the path for the design and development of various sensing devices capable of detecting gynecological problems pertaining to reproductive hormones in females. Thus, the simple design and excellent performance makes our design most efficient and suitable for sensing applications in industrial and biomedical fields. Full article

(This article belongs to the Special Issue Feature Papers on "Hybrid and Composite Crystalline Materials" 2021-2022)

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13 pages, 4876 KiB

Open AccessArticle

Dynamic Tensile Properties of CFRP Manufactured by PCM and WCM: Effect of Strain Rate and Configurations

by Yujin Yang

Crystals 2021, 11(12), 1491; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11121491 - 01 Dec 2021

Cited by 1 | Viewed by 1531

Abstract

Carbon fiber-reinforced plastic (CFRP) is a promising material to achieve lightweight automotive components. The effects of the strain rate and configurations of CFRP on dynamic tensile properties have not yet been fully explored; thus, its lightweight benefits cannot be maximized. In this paper, [...] Read more.

Carbon fiber-reinforced plastic (CFRP) is a promising material to achieve lightweight automotive components. The effects of the strain rate and configurations of CFRP on dynamic tensile properties have not yet been fully explored; thus, its lightweight benefits cannot be maximized. In this paper, the dynamic tensile properties of CFRPs, tested using two different processes with two different resins and four different configurations, were studied with a strain rate from 0.001 to 500 s⁻¹. The tensile strength, modulus, failure strain, and fracture mechanism were analyzed. It was found that the dynamic performance enhances the strength and modulus, whereas it decreases the failure strain. The two processes demonstrated the same level of tensile strength but via different fracture mechanisms. Fiber orientation also significantly affects the fracture mode of CFRP. Resins and configurations both have an influence on strain rate sensitivity. An analytic model was proposed to examine the strain rate sensitivity of CFRPs with different processes and configurations. The proposed model agreed well with the experimental data, and it can be used in simulations to maximize the lightweight properties of CFRP. Full article

(This article belongs to the Special Issue Feature Papers on "Hybrid and Composite Crystalline Materials" 2021-2022)

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Graphical abstract

16 pages, 71941 KiB

Open AccessArticle

Structure and Content Analysis of Raw Materials for Production of Trimanganese Tetraoxide Pigment

by Ruslan Z. Safarov, Jumat B. Kargin, Yelaman K. Aibuldinov, Assemgul K. Zhandildenova, Bolat B. Makhmutov, Alexandr K. Sviderskiy and Nikolai I. Vatin

Crystals 2021, 11(12), 1460; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11121460 - 26 Nov 2021

Cited by 3 | Viewed by 1987

Abstract

The research aims to reveal the structure, phase, and elemental content of manganese ores from deposits—Bogach (Karaganda region, Kazakhstan) and Zhaksy (Akmola region, Kazakhstan). The samples were studied with scanning electron microscopy with energy dispersive analysis (SEM-EDA), X-ray diffractometry (XRD), Infra-red spectroscopy (IRS). [...] Read more.

The research aims to reveal the structure, phase, and elemental content of manganese ores from deposits—Bogach (Karaganda region, Kazakhstan) and Zhaksy (Akmola region, Kazakhstan). The samples were studied with scanning electron microscopy with energy dispersive analysis (SEM-EDA), X-ray diffractometry (XRD), Infra-red spectroscopy (IRS). During the research, structural peculiarities, elemental and phase content of the samples have been revealed. The mineral matter of the Bogach deposit ore mainly consists of hollandite, cryptomelane, braunite, calcite, bixbyite, quartz. The Zhaksy deposit ore includes quartz, hollandite, bixbyite, pyrolusite. Bogach ore includes (wt.%) C(10.68), O(32.00), Mn(43.26), Ca(6.36), Si(3.51), Na(0.52), Al(1.13), Mg(0.69), K(1.85). The elemental content of Mn in Zhaksy ore is two times lower. Zhaksy ore includes (wt.%) C(23.77), O(32.1), Mn(21.81), Si(10.52), Al(5.13), K(1.21), Fe(5.47). The obtained data of the conducted spectral analysis indicate that both samples represent a polymineral heterogeneous structure. Conducted research allows to conclude, that by phase-elemental content the Bogach ore can be used for obtaining trimanganese tetraoxide pigment similar to manganese ores from West Sumatera deposit (Indonesia) by top-down method using grinding with a milling tool and high-temperature sintering. Full article

(This article belongs to the Special Issue Feature Papers on "Hybrid and Composite Crystalline Materials" 2021-2022)

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15 pages, 7495 KiB

Open AccessArticle

Simple Approach to Medical Grade Alumina and Zirconia Ceramics Surface Alteration via Acid Etching Treatment

by Damian Stanislaw Nakonieczny, Aleš Slíva, Zbigniew Paszenda, Marianna Hundáková, Gabriela Kratošová, Sylva Holešová, Justyna Majewska, Piotr Kałużyński, Sajjan Kumar Sathish and Gražyna Simha Martynková

Crystals 2021, 11(10), 1232; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11101232 - 12 Oct 2021

Cited by 10 | Viewed by 2518

Abstract

In order for bioceramics to be further used in composites and their applications, it is important to change the surface so that the inert material is ready to interact with another material. Medical grade alumina and zirconia ceramic powders have been chemically etched [...] Read more.

In order for bioceramics to be further used in composites and their applications, it is important to change the surface so that the inert material is ready to interact with another material. Medical grade alumina and zirconia ceramic powders have been chemically etched with three selected acidic mixtures. Powder samples were taken for characterization, which was the key to evaluating a successful surface change. Changes in morphology, together with chemical composition, were studied using scanning electron microscopy, phase composition using X-ray diffraction methods, and nitrogen adsorption/desorption isotherms are used to evaluate specific surface area and porosity. The application of HF negatively affected the morphology of the material and caused agglomeration. The most effective modification of ceramic powders was the application of a piranha solution to obtain a new surface and a satisfactory degree of agglomeration. The prepared micro-roughness of the etched ceramic would provide an improved surface of the material either for its next step of incorporation into the selected matrix or to directly aid in the attachment and proliferation of osteoblast cells. Full article

(This article belongs to the Special Issue Feature Papers on "Hybrid and Composite Crystalline Materials" 2021-2022)

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14 pages, 4477 KiB

Open AccessArticle

The Effects of Li⁺ Doping on Structure and Upconversion Luminescent Properties for Bi_3.46Ho_0.04Yb_0.5Ti₃O₁₂: xLi Phosphors

by Feng Ren, Jinlei Zhou, Dengpeng Wang, Xianran Wang and Feng Gao

Crystals 2021, 11(10), 1220; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11101220 - 09 Oct 2021

Cited by 5 | Viewed by 1603

Abstract

A series of novel Li⁺ doped Bi_3.46Ho_0.04Yb_0.5Ti₃O₁₂ (BHYTO: xLi, 0 ≤ x ≤ 0.15) upconversion phosphors were prepared through a sol-gel-sintering method. There exist three emission bands centered at 545 nm, 658 [...] Read more.

A series of novel Li⁺ doped Bi_3.46Ho_0.04Yb_0.5Ti₃O₁₂ (BHYTO: xLi, 0 ≤ x ≤ 0.15) upconversion phosphors were prepared through a sol-gel-sintering method. There exist three emission bands centered at 545 nm, 658 nm, and 756 nm in the upconversion emission spectra at 980 nm excitation, corresponding to energy transitions of ⁵F₄/⁵S₂ → ⁵I₈, ⁵F₅ → ⁵I₈ and ⁵F₄/⁵S₂ → ⁵I₇ of Ho³⁺, and the upconversion emission intensity of BHYTO: 0.05Li is about 2.2 times stronger than that of BHYTO samples. The luminescent lifetime of the strongest emission (545 nm) is in the range of 45.25 to 65.99 μs for the different BHYTO: xLi phosphors. The energy transfers during the upconversion pumping process from Yb³⁺ to Ho³⁺ are mainly responsible for all the emissions, each belonging to a double-photon process. Li⁺ mainly entered into the interspace sites or occupied Bi³⁺ sites in Bi₄Ti₃O₁₂ host during the fabrication process according to its dosage, and the possibility is very low for Li⁺ to take part in the energy transfer process directly due to its lack of matching levels with 4f of Ho³⁺ and Yb³⁺. However, Li⁺ doping can not only increase the size of crystal grains to improve crystallinity through XRD analysis, but also reduced oxygen vacancies to decrease the number of quenching centers through XPS analysis. The improved crystallinity and reduced quenching centers are proposed to be the main causes for the enhanced upconversion luminescence of the Li⁺ doped BHYTO phosphor. Full article

(This article belongs to the Special Issue Feature Papers on "Hybrid and Composite Crystalline Materials" 2021-2022)

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8 pages, 2023 KiB

Open AccessCommunication

Green Synthesis of Ge_1−xSn_x Alloy Nanoparticles for Optoelectronic Applications

by Gopal Singh Attar, Mimi Liu, Cheng-Yu Lai and Daniela R. Radu

Crystals 2021, 11(10), 1216; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11101216 - 08 Oct 2021

Cited by 1 | Viewed by 3775

Abstract

Compositionally controlled, light-emitting, group IV semiconductor nanomaterials have potential to enable on-chip data communications and infrared (IR) imaging devices compatible with the complementary metal−oxide−semiconductor (CMOS) technology. The recent demonstration of a direct band gap laser in Ge-Sn alloys opens avenues to the expansion [...] Read more.

Compositionally controlled, light-emitting, group IV semiconductor nanomaterials have potential to enable on-chip data communications and infrared (IR) imaging devices compatible with the complementary metal−oxide−semiconductor (CMOS) technology. The recent demonstration of a direct band gap laser in Ge-Sn alloys opens avenues to the expansion of Si-photonics. Ge-Sn alloys showed improved effective carrier mobility as well as direct band gap behavior at Sn composition above 6–11%. In this work, Ge_1−xSn_x alloy nanoparticles with varying Sn compositions from x = 0.124 to 0.178 were prepared via colloidal synthesis using sodium borohydride (NaBH₄), a mild and non-hazardous reducing reagent. Successful removal of the synthesized long-alkyl-chain ligands present on nanoparticles’ surfaces, along with the passivation of the Ge-Sn nanoparticle surface, was achieved using aqueous (NH₄)₂S. The highly reactive surface of the nanoparticles prior to ligand exchange often leads to the formation of germanium oxide (GeO₂). This work demonstrates that the (NH₄)₂S further acts as an etching reagent to remove the oxide layer from the particles’ surfaces. The compositional control and long-term stability will enable the future use of these easily prepared Ge_1−xSn_x nanoalloys in optoelectronic devices. Full article

(This article belongs to the Special Issue Feature Papers on "Hybrid and Composite Crystalline Materials" 2021-2022)

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14 pages, 2258 KiB

Open AccessArticle

Drying of a Colloidal Suspension Deposited on a Substrate: Experimental and Numerical Studies

by Nathalie Olivi-Tran, Laurent Bonnet and Pascal Etienne

Crystals 2021, 11(7), 829; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11070829 - 17 Jul 2021

Viewed by 2026

Abstract

We studied a colloidal suspension of polystyrene beads deposited on a glass substrate. The glass substrate contained either straight rough areas on the borders of an open channel or only straight rough areas. The drying of the suspension was observed with an optical [...] Read more.

We studied a colloidal suspension of polystyrene beads deposited on a glass substrate. The glass substrate contained either straight rough areas on the borders of an open channel or only straight rough areas. The drying of the suspension was observed with an optical microscope, the light bulb of which acted as an energy source to evaporate the suspension. Moreover, the light bulb of the microscope provided optical pressure due to light. We observed that the colloidal particles were trapped on the rough areas of the substrate and not in the open channel at the end of the drying process. In order to understand the experimental results, we modeled numerically the drying of the suspension using a Molecular Dynamics program. The forces imposed on the substrate by the particles are their weight, the optical pressure due to the light bulb of the optical microscope, the attractive Van der Waals force and the repulsive diffuse layer force. The forces acting between two particles are the attractive Van der Waals forces, the repulsive diffuse layer force and the capillary force. The Gaussian random force (linked to Brownian motion) and the particle liquid viscous drag force (also linked to Brownian motion) are horizontal and applied on one particle. The relation between the normal forces N (forces acting by the particles on the substrate) and the horizontal forces F is Amontons’ third law of friction

F \leq μ_{k} N

; in rough areas of the substrate,

μ_{k}

is larger than in smooth areas. This explains that particles are trapped in the areas with high roughness. Full article

(This article belongs to the Special Issue Feature Papers on "Hybrid and Composite Crystalline Materials" 2021-2022)

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Review

Jump to: Research

30 pages, 3564 KiB

Open AccessReview

A Biomineralization, Mechanical and Durability Features of Bacteria-Based Self-Healing Concrete—A State of the Art Review

by Sardar Kashif Ur Rehman, Faisal Mahmood, Mohammed Jameel, Nadia Riaz, Muhammad Faisal Javed, Abdelatif Salmi and Youssef Ahmed Awad

Crystals 2022, 12(9), 1222; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12091222 - 29 Aug 2022

Cited by 5 | Viewed by 3642

Abstract

Cracking is one of the main ways that concrete ages, allowing pollutants to seep within and potentially lowering the physical and mechanical strength and endurance of concrete structures. One of the healing procedures that merits research is the use of bacterially generated calcium [...] Read more.

Cracking is one of the main ways that concrete ages, allowing pollutants to seep within and potentially lowering the physical and mechanical strength and endurance of concrete structures. One of the healing procedures that merits research is the use of bacterially generated calcium carbonate precipitation in concrete mixtures to mend concrete cracks. The impact of different variables, including the nucleation location, bacterial type, concentration, uratolytic activities, pH, nutrition, and temperature on the bio-mineralization of calcium carbonate are discussed in this review article. ATR-IR (Attenuated Internal Reflectance Fourier Transform Infrared Spectroscopy)/FTIR (Fourier Transform Infrared Spectroscopy)/NMR (Nuclear Magnetic Resonance) and FESEM (Field Emission Scanning Electron Microscope) are among the micro test techniques reviewed along with the biosynthetic pathway of bio mineralized calcium carbonate. The sealing ability and recovery of mechanical and durability properties of bio-mineralized concrete specimen is discussed. Moreover, we discussed the corrosion, damages, and challenges and their detection methods. Also, in-depth knowledge on the use, advancements, and drawbacks of bio-mineralized calcium carbonate is presented. Future potential for bio-mineralized (MICP) self-healing concrete are discussed in the final section. Full article

(This article belongs to the Special Issue Feature Papers on "Hybrid and Composite Crystalline Materials" 2021-2022)

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16 pages, 460 KiB

Open AccessFeature PaperReview

Thermodynamics of Point Defects in Solids and Relation with the Bulk Properties: Recent Results

by Panayiotis A. Varotsos, Nicholas V. Sarlis and Efthimios S. Skordas

Crystals 2022, 12(5), 686; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12050686 - 11 May 2022

Cited by 9 | Viewed by 2322

Abstract

For several decades, the crucial question has arisen as to whether there exists any direct interconnection between the thermodynamic parameters of point defects in solids with the bulk properties of the solid under investigation. To answer this important question, an interrelation of the [...] Read more.

For several decades, the crucial question has arisen as to whether there exists any direct interconnection between the thermodynamic parameters of point defects in solids with the bulk properties of the solid under investigation. To answer this important question, an interrelation of the defect Gibbs energy

g^{i}

in solids with bulk properties has been proposed almost half a century ago. Considering that

g^{i}

corresponds to an isobaric and isothermal process, this interrelation states that, for different processes (defect formation, self-diffusion activation, and heterodiffusion),

g^{i}

is proportional to the isothermal bulk modulus B and the mean volume per atom

Ω

, termed cB

Ω

model. Here, we review several challenging applications of this interrelation that appeared during the last decade (2011–2021), including high pressure diamond anvil measurements, high T

_{c}

superconductors, nuclear fuels, and materials for micro-electronics devices, applications of usefulness in Geophysics and Seismology, a problem of major technological interest, search for compositions of better target properties in Cu-Co-Si alloys via machine learning as well as two independent studies on the physical origin of this interrelation that has been further strengthened during the last few years. Full article

(This article belongs to the Special Issue Feature Papers on "Hybrid and Composite Crystalline Materials" 2021-2022)

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23 pages, 5607 KiB

Open AccessReview

Self-Assembled Nanocomposites and Nanostructures for Environmental and Energy Applications

by Sujie Chang, Xiaomin Wang, Qiaoling Hu, Xigui Sun, Aiguo Wang, Xiaojun Dong, Yu Zhang, Lei Shi and Qilei Sun

Crystals 2022, 12(2), 274; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst12020274 - 17 Feb 2022

Cited by 1 | Viewed by 1977

Abstract

Self-assembled nanocomposites are attracting considerable attention owing to their controllable architectures and self-assembly processes, as well as the increase in worldwide environmental effects and energy needs. Further understanding of the self-assembly procedure for improving environmental and energy applications would advance the design and [...] Read more.

Self-assembled nanocomposites are attracting considerable attention owing to their controllable architectures and self-assembly processes, as well as the increase in worldwide environmental effects and energy needs. Further understanding of the self-assembly procedure for improving environmental and energy applications would advance the design and manufacture of nanomaterials for various applications. These materials can be grouped into major categories for various application fields, including powder photocatalysts, membrane photocatalysts, and thin-film thermoelectric nanomaterials. These self-assembled nanomaterials can be used for environmental and energy applications, such as wastewater purification, hydrogen production by water splitting, energy storage, and energy harvesting. In this review, a brief introduction to the definitions and classifications of self-assembled nanocomposites is provided. We aim to provide a summary of the recent research related to self-assembled nanocomposites and nanostructures used for environmental and energy applications. Moreover, typical examples and discussions are aimed at demonstrating the advantages of self-assembled nanostructures. At the end of each section, the structural properties and the application of the nanocomposite or nanostructure are summarized. Finally, we provide perspectives for future research on the design and fabrication of self-assembled nanocomposites and nanostructures. Full article

(This article belongs to the Special Issue Feature Papers on "Hybrid and Composite Crystalline Materials" 2021-2022)

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15 pages, 1096 KiB

Open AccessReview

Molecular Simulation of External Electric Fields on the Crystal State: A Perspective

by Niall J. English

Crystals 2021, 11(11), 1405; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11111405 - 18 Nov 2021

Cited by 1 | Viewed by 1763

Abstract

Unpacking the mechanistic insights into how externally applied electric fields affect the physicochemical properties of crystals represents a challenge of great importance for a plethora of natural phenomena, in addition to a broad array of industrial operations and technologies. As such, the key [...] Read more.

Unpacking the mechanistic insights into how externally applied electric fields affect the physicochemical properties of crystals represents a challenge of great importance for a plethora of natural phenomena, in addition to a broad array of industrial operations and technologies. As such, the key goals in such field effect studies centre around how thermodynamic and kinetic relaxation processes in crystals are affected, including charge carrier conduction and energy transfer processes, and this is a very recent area of fundamental scrutiny. Indeed, in recent years, there has been a steadily mounting number of reports of field-manipulated crystal-state phenomena. Taking as the background a range of natural phenomena, phenomenological theory, state-of-the-art experiments and technological observations, the present review examines the role of nonequilibrium molecular simulation in its scrutiny of intra-crystal phenomena from an atomistic viewpoint, in addition to providing a framework for a predictive molecular design philosophy by which to refine field crystal understanding. Full article

(This article belongs to the Special Issue Feature Papers on "Hybrid and Composite Crystalline Materials" 2021-2022)

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19 pages, 12116 KiB

Open AccessReview

B-Site Cation Ordering in Films, Superlattices, and Layer-by-Layer-Grown Double Perovskites

by Philipp Ksoll, Christoph Meyer, Leonard Schüler, Vladimir Roddatis and Vasily Moshnyaga

Crystals 2021, 11(7), 734; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11070734 - 25 Jun 2021

Cited by 12 | Viewed by 2515

Abstract

The preparation of cation-ordered thin films of correlated oxides is of great interest for both fundamental and applied research. The scientific long-term vision is strongly motivated by the perspective of studying electronic correlations in condensed matter without the presence of chemical or quenched [...] Read more.

The preparation of cation-ordered thin films of correlated oxides is of great interest for both fundamental and applied research. The scientific long-term vision is strongly motivated by the perspective of studying electronic correlations in condensed matter without the presence of chemical or quenched disorder. A promising material platform provides double perovskite A₂BB’O₆ bulk samples with different types of B/B’ ordering. However, the growth of A- and/or B-site-ordered correlated oxide thin films is known to be a challenging task. In this review, we evaluate the growth of double perovskite A₂BB’O₆ thin films by means of well-elaborated physical vacuum deposition techniques, such as pulsed laser deposition (PLD) and sputtering and compare them with a close-to-equilibrium growth with the metalorganic aerosol deposition (MAD) technique. The latter was further developed to grow an emergent interfacial double perovskite phase in LaNiO₃/LaMnO₃ superlattices, and finally, by way of a layer-by-layer route. The growth of La₂CoMnO₆ films on SrTiO₃(111) substrates by sequential deposition of single perovskite layers of LaCoO₃/LaMnO₃/LaCoO₃/… was demonstrated and the film properties were compared to those obtained within the state-of-the art growth mode. Full article

(This article belongs to the Special Issue Feature Papers on "Hybrid and Composite Crystalline Materials" 2021-2022)

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15 pages, 882 KiB

Open AccessReview

Molecular Simulation of Crystallisation in External Electric Fields: A Review

by Niall J. English

Crystals 2021, 11(3), 316; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11030316 - 22 Mar 2021

Cited by 3 | Viewed by 2619

Abstract

Elucidating the underlying mechanisms of molecular solidification in both homo- and hetero-geneous systems is of paramount importance for a large swathe of natural phenomena (whether on Earth or throughout the Universe), as well as a whole litany of industrial processes. One lesser-studied aspect [...] Read more.

Elucidating the underlying mechanisms of molecular solidification in both homo- and hetero-geneous systems is of paramount importance for a large swathe of natural phenomena (whether on Earth or throughout the Universe), as well as a whole litany of industrial processes. One lesser-studied aspect of these disorder-order transitions is the effect of external applied fields, shifting both thermodynamic driving forces and underlying kinetics, and, indeed, fundamental mechanisms themselves. Perhaps this is nowhere more apparent than in the case of externally-applied electric fields, where there has been a gradually increasing number of reports in recent years of electro-manipulated crystallisation imparted by such electric fields. Drawing motivations from both natural phenomena, state-of-the-art experiments and, indeed, industrial applications, this review focusses on how non-equilibrium molecular simulation has helped to elucidate crystallisation phenomena from a microscopic perspective, as well as offering an important, predictive molecular-design approach with which to further refine in-field-crystallisation operations. Full article

(This article belongs to the Special Issue Feature Papers on "Hybrid and Composite Crystalline Materials" 2021-2022)

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