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Crystals, Volume 11, Issue 5 (May 2021) – 117 articles

Cover Story (view full-size image): Lithium niobate (LiNbO3) crystal boule quality depends on the technological conditions of crystal growth: the variation in charge synthesis type, stoichiometry, dopant type, concentration, etc. The figure shows a macrodefect cellular structure in a doped LiNbO3:Zn crystal: a—at the bottom; b—on the Z surface through the X surface; c—observation in the DIC mode.View this paper
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Article
Study of the Preferred Orientation of Hydroxyapatite in Ivory from Zimbabwe and Mammoth Ivory from Siberia
Crystals 2021, 11(5), 572; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11050572 - 20 May 2021
Viewed by 438
Abstract
In this paper, the pole figures plotted from X-ray diffraction data are employed to analyze the orientation of hydroxyapatite in ivory and mammoth ivory for the first time. The results present evidence of the lamellar structure and the hydroxyapatite appeared as tabular. A [...] Read more.
In this paper, the pole figures plotted from X-ray diffraction data are employed to analyze the orientation of hydroxyapatite in ivory and mammoth ivory for the first time. The results present evidence of the lamellar structure and the hydroxyapatite appeared as tabular. A preferred orientation of hydroxyapatite was revealed in terms of the calculated orientation factor and the characteristics found in the pole figures. The c-axes of hydroxyapatite are mainly oriented along the growth direction. Both a-axes are on the left of the angle bisector of Retzius. Approximately 25–30° separates the a-axes and the angle bisector of Retzius in ivory, whereas the figure is approximately 10–15° in mammoth ivory. Our work is significant in providing more accurate knowledge of the shapes and organizational state of bio-mineral crystals and providing insight into crystal formation and development in bio-mineralization. Full article
(This article belongs to the Special Issue Gem Crystals)
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Article
Synthesis of 1-[(Aryl)(3-amino-5-oxopyrazolidin-4-ylidene) methyl]-2-oxo-1,2-dihydroquinoline-3-carboxylic Acid Derivatives and Their Breast Anticancer Activity
Crystals 2021, 11(5), 571; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11050571 - 20 May 2021
Viewed by 425
Abstract
This research aimed to produce new 1-[(aryl)(3-amino-5-oxopyrazolidin-4-ylidene) methyl]-2-oxo-1,2-dihydroquinoline-3-carboxylic acid derivatives and check their anticancer effect against the breast cancer MCF-7 cell line. The 2-oxo-1,2-dihydroquinoline-3-carboxylic acid (4) compound was obtained by hydrolyzing ethyl 2-oxo-1,2-dihydroquinoline-3-carboxylate (2) with thiourea and anhydrous potassium [...] Read more.
This research aimed to produce new 1-[(aryl)(3-amino-5-oxopyrazolidin-4-ylidene) methyl]-2-oxo-1,2-dihydroquinoline-3-carboxylic acid derivatives and check their anticancer effect against the breast cancer MCF-7 cell line. The 2-oxo-1,2-dihydroquinoline-3-carboxylic acid (4) compound was obtained by hydrolyzing ethyl 2-oxo-1,2-dihydroquinoline-3-carboxylate (2) with thiourea and anhydrous potassium carbonate ethanol, which was then treated with ethyl 3-substituted 2-cyanoacrylates (6) in the presence of triethylamine in diethyl formamide to give 1-[2-(ethoxy)carbonyl-2-cyano-1-arylvinyl]-2-oxo-1,2-dihydroquinoline-3-carboxylic (7a,d). Cyclization of compound 7 with hydrazine hydrate ethanol inferred the association of 1-[(aryl)(3 amino-5-oxopyrazolidin-4-ylidene)methyl-2-oxo-1,2-dihydroquinol-3-carboxylates (8a,d). Spectroscopic and micro-analytical techniques such as IR, NMR, and elemental analysis were used to validate the structure of the synthesized organic compounds. The anticancer effects of the synthesized compounds 7ad and 8ad were tested by using the MTT assay on the MCF-7 cell line. When compared to the reference compound Dox, the compounds 7b,c and 8ac demonstrated strong anticancer activity against the MCF-7 cell line. The anticancer effects of the synthesized compounds 7ad and 8ad were tested against the MCF-7 cell line, using MTT assay. The compounds 7b,c and 8ac showed significant anticancer activity compared to the reference compound Dox against the MCF-7 cell line. Full article
(This article belongs to the Special Issue Research about Vital Organic Chelates and Metal Ion Complexes)
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Article
Design and Evaluation the Anti-Wear Property of Inorganic Fullerene Tungsten Disulfide as Additive in PAO6 Oil
Crystals 2021, 11(5), 570; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11050570 - 20 May 2021
Viewed by 437
Abstract
Inorganic fullerene-like tungsten disulfide particles have been proved to have good anti-friction and anti-wear properties as lubricating materials. As far as we know, however, when it is used as a lubricant additive, its behavior and action mechanism in the friction process are rarely [...] Read more.
Inorganic fullerene-like tungsten disulfide particles have been proved to have good anti-friction and anti-wear properties as lubricating materials. As far as we know, however, when it is used as a lubricant additive, its behavior and action mechanism in the friction process are rarely studied. Herein, IF–WS2 particles were synthesized by a Chemical Vapor Deposition (CVD) method. The effect of IF–WS2 particle concentrations in the PAO6 oil on the tribological behaviors was investigated with a four-ball wear machine at both 75 and 100 °C. Additionally, the analyzed morphology and composition of nanomaterials and worn surfaces were analyzed by Scanning electron microscopy (SEM), Transmission Electron Microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The friction behavior in actual working conditions was studied by a wear testing machine. The experimental results show that compared with the original PAO6 oil, at a dispersion of 0.25 wt% in PAO6 oil, the IF–WS2 particles showed the best performance in terms of coefficient of friction, wear scar diameter and wear mass, which significantly reduced by 27%, 43% and 87%, respectively. At the same time, in the process of friction, it was found that IF–WS2 particles accumulated in the depressions to fill the scratches, and adsorption films and chemical films, including FeS2, WS2 and WO3, were formed on the worn surfaces to avoid the direct contact among the friction pairs more effectively, resulting in the improved anti-wear performances. Additionally, the addition of IF–WS2 particles effectively delayed the rise of lubricating oil temperature. In addition, dispersant span 80 can effectively improve the dispersion and stability of IF–WS2 in PAO6. This work provides us for understanding the effective lubrication mechanism of IF–WS2 particles in more detail and having a new acknowledge of the comprehensive performance of IF–WS2/PAO6 oil. Full article
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Article
3D-FEM Simulation of Hot Rolling Process and Characterization of the Resultant Microstructure of a Light-Weight Mn Steel
Crystals 2021, 11(5), 569; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11050569 - 20 May 2021
Viewed by 390
Abstract
Computational simulation has become more important in the design of thermomechanical processing since it allows the optimization of associated parameters such as temperature, stresses, strains and phase transformations. This work presents the results of the three-dimensional Finite Element Method (FEM) simulation of the [...] Read more.
Computational simulation has become more important in the design of thermomechanical processing since it allows the optimization of associated parameters such as temperature, stresses, strains and phase transformations. This work presents the results of the three-dimensional Finite Element Method (FEM) simulation of the hot rolling process of a medium Mn steel using DEFORM-3D software. Temperature and effective strain distribution in the surface and center of the sheet were analyzed for different rolling passes; also the change in damage factor was evaluated. According to the hot rolling simulation results, experimental hot rolling parameters were established in order to obtain the desired microstructure avoiding the presence of ferrite precipitation during the process. The microstructural characterization of the hot rolled steel was carried out using optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). It was found that the phases present in the steel after hot rolling are austenite and α′-martensite. Additionally, to understand the mechanical behavior, tensile tests were performed and concluded that this new steel can be catalogued in the third automotive generation. Full article
(This article belongs to the Special Issue Study of Structure, Heat Treatment and Properties of Steels)
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Article
Novel Dihydro-1,3,2H-benzoxazine Derived from Furfurylamine: Crystal Structure, Hirshfeld Surface Analysis, Photophysical Property, and Computational Study
Crystals 2021, 11(5), 568; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11050568 - 20 May 2021
Viewed by 1001
Abstract
Dihydro-1,3,2H-benzoxazines (or benzoxazine monomers) are a class of compounds that have been widely utilized in many areas such as the production of the functional polymers and optoelectronic materials. The structure variety of the benzoxazines plays a vital role in their desired [...] Read more.
Dihydro-1,3,2H-benzoxazines (or benzoxazine monomers) are a class of compounds that have been widely utilized in many areas such as the production of the functional polymers and optoelectronic materials. The structure variety of the benzoxazines plays a vital role in their desired properties. The effort of synthesizing functionalized benzoxazines from bioresources is of interest for sustainable development. Herein, we report the synthesis of the novel benzoxazine monomer referred to as 3-(furan-2-ylmethyl)-6-methyl-3,4-dihydro-2H-benzo[e][1,3]oxazine or benzoxazine (I) from a one-pot Mannich reaction using p-cresol, paraformaldehyde, and furfurylamine (a bio-derived amine). An X-ray crystallographic study was performed at low temperature (100 K) to obtain the structural characteristics of the benzoxazine (I). The result reveals that the oxazine ring adopts a half chair conformation to locate all the members of the benzoxazine ring as planar as possible by employing the expansion of the bond angles within the ring. Apart from the structural parameters, the intermolecular interactions were also examined. It was found that the significant interactions within the crystal are C–H···N, C–H···O, and the C–H···π interactions. The C–H···N interactions link the benzoxazine (I) molecules into an infinite molecular chain, propagating along the [100] direction. Hirshfeld surfaces and their corresponding fingerprint plots were comprehensively analyzed to confirm and quantify the significance of these interactions. Moreover, the photophysical properties of the benzoxazine (I) were investigated in solvents with various polarities. The corresponding relations between the structural features, frontier molecular orbitals, and absorption-and-emission characteristics were proposed and explained according to the DFT and TD-DFT calculations. Full article
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Article
Low-Energy Optical Conductivity of TaP: Comparison of Theory and Experiment
Crystals 2021, 11(5), 567; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11050567 - 19 May 2021
Cited by 1 | Viewed by 489
Abstract
The ab-plane optical conductivity of the Weyl semimetal TaP is calculated from the band structure and compared to the experimental data. The overall agreement between theory and experiment is found to be best when the Fermi level is slightly (20 to 60 meV) [...] Read more.
The ab-plane optical conductivity of the Weyl semimetal TaP is calculated from the band structure and compared to the experimental data. The overall agreement between theory and experiment is found to be best when the Fermi level is slightly (20 to 60 meV) shifted upwards in the calculations. This confirms a small unintentional doping of TaP, reported earlier, and allows a natural explanation of the strong low-energy (50 meV) peak seen in the experimental ab-plane optical conductivity: this peak originates from transitions between the almost parallel non-degenerate electronic bands split by spin-orbit coupling. The temperature evolution of the peak can be reasonably well reproduce by calculations using an analog of the Mott formula. Full article
(This article belongs to the Special Issue Advances in Topological Materials)
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Article
Optical Parametric Oscillation with Ultra-Low Power Threshold in a Dimer of Active-Passive Cavities
Crystals 2021, 11(5), 566; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11050566 - 19 May 2021
Viewed by 494
Abstract
Optical parametric oscillation can convert the input laser into a couple of coherent optical output with signal and idler frequencies. It is an important method for the realization of the broadband middle infrared tunable lasers. The optical parametric oscillation process depends on the [...] Read more.
Optical parametric oscillation can convert the input laser into a couple of coherent optical output with signal and idler frequencies. It is an important method for the realization of the broadband middle infrared tunable lasers. The optical parametric oscillation process depends on the ultra-fast non-linear response of matter to light with a certain pump power. Therefore, reducing the pump threshold of the optical parametric oscillation process and improving the energy conversion efficiency are of great significance to the study of non-linear optics. In this paper, we construct a dimer system that couples a passive non-linear resonator to an active resonator. Based on the dimer system, an ultra-low threshold optical parametric oscillation generation method is proposed. By coupling the gain pump mode, the non-linear effect is effectively enhanced, the pump power threshold is reduced to half of when there is no gain, and the energy conversion efficiency is increased. We believe this research provides a feasible method for a low-threshold tunable and easy-to-integrate optical parametric oscillation laser source. Full article
(This article belongs to the Special Issue Micro and Nano Optics for Advanced Sensing Technology)
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Article
Synthesis and Characterization of Some New Coumarin Derivatives as Probable Breast Anticancer MCF-7 Drugs
Crystals 2021, 11(5), 565; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11050565 - 19 May 2021
Viewed by 453
Abstract
This study aimed to synthesize quinolinone derivatives and investigate their cytotoxic activity. The compound 1-azacoumarin-3-carboxylic acid (2-oxo-1H-quinoline-3-carboxylic acid) was obtained via the cyclocondensation of 2-hydroxybenzaldehyde with diethyl malonate in base catalyst to give ethyl coumarin-3-carboxylate, followed by the ammonolysis of ester (ethyl coumarin-3-carboxylate) [...] Read more.
This study aimed to synthesize quinolinone derivatives and investigate their cytotoxic activity. The compound 1-azacoumarin-3-carboxylic acid (2-oxo-1H-quinoline-3-carboxylic acid) was obtained via the cyclocondensation of 2-hydroxybenzaldehyde with diethyl malonate in base catalyst to give ethyl coumarin-3-carboxylate, followed by the ammonolysis of ester (ethyl coumarin-3-carboxylate) with ammonia in the presence of anhydrous potassium carbonate. Treatment of 2-oxo-1H-quinoline-3-carboxylic acid with acetic anhydride, cinnamaldehyde, cinnamic acid and methyl 5-phenyl-2-cyano-2,4-pentadienoate under different conditions led to the formation of 1 (substituted) aza coumarin-3-carboxylic acids (1-N-(acetyl)-azacoumarin-3-carboxylic acid, 1-N-(2-Formyl-1-phenyl) vinyl-azacoumarin-3-carboxylic acids, 1-N-[2-(Hydroxy) carbonyl-1-(Phenyl) vinyl]-azacoumarin-3-carboxylic acid and 1-N-(4-Cyano-5-methoxy-5-oxo-1-Phenylpenta-1,3-diene-1-y)-azacoumarin-3-carboxylic 284 acid), respectively. The structures of synthesized 1-(substituted) azacoumarin-3-carboxylic acids were confirmed based on spectroscopic methods (IR and NMR), along with elemental analyses. Interestingly compound 6 demonstrated probable impacts as an anti-cancer drug against the MCF-7 cell line. The mechanism of action was assessed using a flow cytometric assay. The outcomes revealed that compound 6 could arrest the cell cycle at G2/M phase and pre-G1 apoptosis. Full article
(This article belongs to the Special Issue Research about Vital Organic Chelates and Metal Ion Complexes)
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Article
Analysis of Different Mould Section Sizes to Optimize the Submerged Entry Nozzle to Measure the Meniscus Fluctuation in a Continuous Casting Mould
Crystals 2021, 11(5), 564; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11050564 - 19 May 2021
Viewed by 333
Abstract
An experimental investigation has been carried out to analyse different mould section sizes to measure the meniscus fluctuation by varying different liquid flow rates and different submerged entry nozzle port angles, i.e., 0° port angles, 15° downward and 15° upward port angles. The [...] Read more.
An experimental investigation has been carried out to analyse different mould section sizes to measure the meniscus fluctuation by varying different liquid flow rates and different submerged entry nozzle port angles, i.e., 0° port angles, 15° downward and 15° upward port angles. The terms of maximum surface wave fluctuation and standard deviation have been analysed for the above mentioned parameters. It was observed that a submerged entry nozzle with 0° port was found to be superior when it was compared with a 15° downward and 15° upward port nozzle. By conducting an experiment, it was observed that as the water flow rate increased, the maximum wave amplitude was found to be increasing, which results in more turbulence. Different mould section sizes were analysed to provide background information to the steelmaker to analyse the behaviour of fluid flow pattern. The operating parameters of the result obtained from the present setup were compared with the published literature, and a scale down of slab moulds can be justifiedregarding the rough flow pattern in the mould but can lack accuracy. The reason behind this statement is that the integral length scales of the turbulent flow between scaled down and full scale models can be different. Therefore, details of the flow pattern can become great differences between both types of models. Full article
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Article
Surface Enhanced Infrared Absorption Studies of SiO2–TiO2–Ag Nanofibers: Effect of Silver Electrodeposition Time on the Amplification of Signals
Crystals 2021, 11(5), 563; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11050563 - 19 May 2021
Viewed by 470
Abstract
Surface Enhanced on Infrared Absorption (SEIRAS) and Raman Spectroscopy (SERS) are nondestructive analytic techniques used to detect low concentrations and recognize the fingerprints of molecules. The recognition of the absorption from samples by conventional infrared spectroscopy (IR) via Attenuated Total Reflection (ATR) is [...] Read more.
Surface Enhanced on Infrared Absorption (SEIRAS) and Raman Spectroscopy (SERS) are nondestructive analytic techniques used to detect low concentrations and recognize the fingerprints of molecules. The recognition of the absorption from samples by conventional infrared spectroscopy (IR) via Attenuated Total Reflection (ATR) is difficult for molecules with a low signal strength. However, developed structures with SERS and SEIRAS effect present problems such as high cost, low stability, and low compatibility. Research into new media to obtain greater amplification is largely based on the creation of nanoscale structures with symmetrical arrangements and reproducible distances, resulting in aggregates of nanoparticles that help generate hot spots which are active for amplification. The sol-gel and electrospinning method for the obtention of ceramics provides an alternative means by which to produce said substrates. Fibers of nanometric scale provide an increase of surface area which allows more contact to occur with analytes. Consequently, in this study, a silica-titania-silver nanostructured support that amplifies signal intensity for Raman and infrared spectroscopy was developed. The silica-titania support was developed by sol-gel and electrospinning techniques, and the as spun fibers were treated at 800 °C. Then, the ceramic fibrous membrane was placed on conductive indium tin oxide plastic to be doped with silver using an electroplating technique, varying the silver nitrate concentration (5, 10 and 20 mM), as well as electrodeposition times (1, 2, 5 and 10 min), with a constant voltage (1 V). Twelve different supports were obtained that showed amplification. The enhancement of infrared signals from pyridine and crystal violet molecules adsorbed on silica-titania-silver (SiO2–TiO2–Ag) nanofibers was studied in situ by Attenuated Total Reflection-Fourier Transformed Infrared Spectroscopy (ATR-FTIR). The highest amplification was obtained by the support doped at 10 min in a 10 mM concentration, with an amplification factor of 2.74 in the band localized at 3301 cm−1. In Raman spectroscopy, the highest amplification factor was 27.03, on the support doped for 5 min at a concentration of 5 mM. Full article
(This article belongs to the Special Issue Advances in Hybrid and Composite Materials Based on Micro/Nanofibers)
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Article
Quartz Crystal Microbalance Genosensing of Brettanomyces bruxellensis Yeast in Wine Using a Rapid and Efficient Drop and Collect Protocol
Crystals 2021, 11(5), 562; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11050562 - 18 May 2021
Viewed by 515
Abstract
A miniaturized quartz crystal microbalance (QCM) genosensor is proposed for sensitive and real-time detection of short ssDNA sequences (53 bp) or DNA extracted from Brettanomyces bruxellensis (Brett) yeast cells. The presence of Brett yeast causes a depreciation of the quality of aged fine [...] Read more.
A miniaturized quartz crystal microbalance (QCM) genosensor is proposed for sensitive and real-time detection of short ssDNA sequences (53 bp) or DNA extracted from Brettanomyces bruxellensis (Brett) yeast cells. The presence of Brett yeast causes a depreciation of the quality of aged fine wines, producing molecules of unpleasant odors and biogenic amines that are harmful to human health. More specifically, standard quartz crystal (S-QCM) and homemade 4 nm gold transmission electron microscopy (TEM)-grid patterned quartz (multi-TEM QCM) are herein proposed for biofunctionalization steps with different ssDNA sequences. By employing a rapid and efficient drop and collect protocol, the specific detection of 1 pg/µL ssDNA Brett of a short sequence and 100 ng/μL DNA of B. bruxellensis extracted from a wine sample (VR2008) is reported. Full article
(This article belongs to the Special Issue DNA and Small Molecular Complex Crystallization)
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Communication
User-Tailored Orthosis Design for 3D Printing with PLACTIVE: A Quick Methodology
Crystals 2021, 11(5), 561; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11050561 - 18 May 2021
Viewed by 488
Abstract
This paper proposes a methodology for user-tailored orthosis design for 3D printing that aims to give a non-expert, user-oriented tool that easily generates a customized orthosis. Additionally, this work aims to verify the biocompatibility of the PLACTIVE™ (PLACTIVE AN1™, nano-additive concentration 1%, Copper [...] Read more.
This paper proposes a methodology for user-tailored orthosis design for 3D printing that aims to give a non-expert, user-oriented tool that easily generates a customized orthosis. Additionally, this work aims to verify the biocompatibility of the PLACTIVE™ (PLACTIVE AN1™, nano-additive concentration 1%, Copper 3D, Santiago, Chile) filament after extrusion to check its feasibility for 3D printed orthoses. A forefinger and a thumb orthosis were successfully designed applying the proposed methodology. The results showed that the proposed methodology is able to generate simple and practical orthoses through a fairly easy and intuitive procedure. Furthermore, experimental tests showed that the biocompatibility of the PLACTIVE™ filament is not affected after extrusion process, suggesting that it is a feasible material for 3D-printed orthoses. Full article
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Article
Black Phosphorus-Molybdenum Disulfide Hetero-Junctions Formed with Ink-Jet Printing for Potential Solar Cell Applications with Indium-Tin-Oxide
Crystals 2021, 11(5), 560; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11050560 - 18 May 2021
Viewed by 411
Abstract
In this work, we implemented liquid exfoliation to inkjet-print two-dimensional (2D) black phosphorous (BP) and molybdenum disulfide (MoS2) p–n heterojunctions on a standard indium tin oxide (ITO) glass substrate in a vertical architecture. We also compared the optical and electrical properties [...] Read more.
In this work, we implemented liquid exfoliation to inkjet-print two-dimensional (2D) black phosphorous (BP) and molybdenum disulfide (MoS2) p–n heterojunctions on a standard indium tin oxide (ITO) glass substrate in a vertical architecture. We also compared the optical and electrical properties of the inkjet-printed BP layer with that of the MoS2 and the electrical properties of the mechanically exfoliated MoS2 with that of the inkjet-printed MoS2. We found significant differences in the optical characteristics of the inkjet-printed BP and MoS2 layers attributed to the differences in their underlying crystal structure. The newly demonstrated liquid exfoliated and inkjet-printed BP–MoS2 2D p–n junction was also compared with previous reports where mechanically exfoliated BP–MoS2 2D p–n junction were used. The electronic transport properties of mechanically exfoliated MoS2 membranes are typically better compared to inkjet-printed structures but inkjet printing offers a cost-effective and quicker way to fabricate heterostructures easily. In the future, the performance of inkjet-printed structures can be further improved by employing suitable contact materials, amongst other factors such as modifying the solvent chemistries. The architecture reported in this work has potential applications towards building solar cells with solution processed 2D materials in the future. Full article
(This article belongs to the Special Issue Design, Characterization, and Application of 2D Materials)
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Review
Milled Surface Integrity: Application to Fixed Dental Prosthesis
Crystals 2021, 11(5), 559; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11050559 - 18 May 2021
Viewed by 423
Abstract
Surface integrity is a multiphysics (biological, mechanical, optical, chemical, esthetic, etc.) and multiscale (from nm to mm) concept. It is defined as the residual signature left on the surface by the manufacturing or post-treatment process and permits correlating the process with the expected [...] Read more.
Surface integrity is a multiphysics (biological, mechanical, optical, chemical, esthetic, etc.) and multiscale (from nm to mm) concept. It is defined as the residual signature left on the surface by the manufacturing or post-treatment process and permits correlating the process with the expected surface functionalities. Thanks to the advances made in mechanical engineering, the concept of surface integrity has been transposed to dentistry and oral science. The surface integrity concept transposed to fixed dental prostheses is presented in this article. The main components of surface integrity and their correlations within the triptych of surface integrity–process–clinical functionalities are presented. Full article
(This article belongs to the Special Issue Biomaterials Surface Integrity)
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Article
Experimental Evaluation of Untreated and Pretreated Crumb Rubber Used in Concrete
Crystals 2021, 11(5), 558; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11050558 - 17 May 2021
Cited by 1 | Viewed by 551
Abstract
The present research aims at evaluating the mechanical performance of untreated and treated crumb rubber concrete (CRC). The study was also conducted to reduce the loss in mechanical properties of CRC. In this study, sand was replaced with crumb rubber (CR) with 0%, [...] Read more.
The present research aims at evaluating the mechanical performance of untreated and treated crumb rubber concrete (CRC). The study was also conducted to reduce the loss in mechanical properties of CRC. In this study, sand was replaced with crumb rubber (CR) with 0%, 5%, 10%, 15%, and 20% by volume. CR was treated with NaOH, lime, and common detergent for 24 h. Furthermore, water treatment was also carried out. All these treatments were done to enhance the mechanical properties of concrete that are affected by adding CR. The properties that were evaluated are compressive strength, indirect tensile strength, unit weight, ultrasonic pulse velocity, and water absorption. Compressive strength was assessed after 7 and 28 days of curing. The mechanical properties were decreased by increasing the percentage of the CR. The properties were improved after the treatment of CR. Lime treatment was found to be the best treatment of all four treatments followed by NaOH treatment and water treatment. Detergent treatment was found to be the worse treatment of all four methods of treatment. Despite increasing the strength it contributed to strength loss. Full article
(This article belongs to the Special Issue Advances in Sustainable Concrete System)
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Article
Study on Microstructure and Properties of 12Ag–Cu–Zn–Sn Cadmium-Free Filler Metals with Trace in Addition
Crystals 2021, 11(5), 557; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11050557 - 16 May 2021
Viewed by 535
Abstract
The effect of different In contents on the melting characteristics, mechanical properties, and microstructure of 12Ag–Cu–Zn–Sn filler metal was investigated in this paper, and flame brazing of 304 stainless steel and copper plates was done using the 12Ag–Cu–Zn–Sn–xIn filler metal. The [...] Read more.
The effect of different In contents on the melting characteristics, mechanical properties, and microstructure of 12Ag–Cu–Zn–Sn filler metal was investigated in this paper, and flame brazing of 304 stainless steel and copper plates was done using the 12Ag–Cu–Zn–Sn–xIn filler metal. The results indicate that adding appropriate amount of In can evidently decrease the solidus and liquidus temperatures and improve the wettability of the low silver based filler metals. In addition, the shear strength of 304 stainless steel and copper plates joint brazed by 12Ag–Cu–Zn–Sn–1In are satisfactory due to the solution strength effect, and scanning electron microscopy examination of the braze-zone revealed that more relatively sound joints were obtained when brazing was done with 12Ag–Cu–Zn–Sn–xIn filler metal than with Indium free one; its performance is comparable to that of the joint brazed with the 20Ag–Cu–Zn–Sn filler metal, having a remarkable silver-saving effect. Full article
(This article belongs to the Special Issue Advances of Welding Materials)
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Article
Effect of Recycled Coarse Aggregate and Bagasse Ash on Two-Stage Concrete
Crystals 2021, 11(5), 556; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11050556 - 16 May 2021
Viewed by 884
Abstract
Numerous research studies have been conducted to improve the weak properties of recycled aggregate as a construction material over the last few decades. In two-stage concrete (TSC), coarse aggregates are placed in formwork, and then grout is injected with high pressure to fill [...] Read more.
Numerous research studies have been conducted to improve the weak properties of recycled aggregate as a construction material over the last few decades. In two-stage concrete (TSC), coarse aggregates are placed in formwork, and then grout is injected with high pressure to fill up the voids between the coarse aggregates. In this experimental research, TSC was made with 100% recycled coarse aggregate (RCA). Ten percent and twenty percent bagasse ash was used as a fractional substitution of cement along with the RCA. Conventional concrete with 100% natural coarse aggregate (NCA) and 100% RCA was made to determine compressive strength only. Compressive strength reduction in the TSC was 14.36% when 100% RCA was used. Tensile strength in the TSC decreased when 100% RCA was used. The increase in compressive strength was 8.47% when 20% bagasse ash was used compared to the TSC mix that had 100% RCA. The compressive strength of the TSC at 250 °C was also determined to find the reduction in strength at high temperature. Moreover, the compressive and tensile strength of the TSC that had RCA was improved by the addition of bagasse ash. Full article
(This article belongs to the Special Issue Advances in Sustainable Concrete System)
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Article
Enhanced Electrostrictive Coefficient and Suppressive Hysteresis in Lead-Free Ba(1−x)SrxTiO3 Piezoelectric Ceramics with High Strain
Crystals 2021, 11(5), 555; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11050555 - 16 May 2021
Viewed by 447
Abstract
Lead-free piezoelectric ceramics with both low hysteresis and superior electrostrictive coefficient features are crucial toward providing desired performance for intelligent electrical devices, especially in high-precision displacement actuators. In this work, we propose a novel scenario, which is to design the phase transition around [...] Read more.
Lead-free piezoelectric ceramics with both low hysteresis and superior electrostrictive coefficient features are crucial toward providing desired performance for intelligent electrical devices, especially in high-precision displacement actuators. In this work, we propose a novel scenario, which is to design the phase transition around ambient temperature to enhance electrostrictive effect and inhibit hysteresis. In other words, the dense ceramics with cubic phases (C) and tetragonal phases (T) coexisting at RT (room temperature) were designed. According to this scenario, the Ba(1−x)SrxTiO3 (abbreviated as BT-100xST) ceramics were fabricated by the conventional solid-state reaction method. The relaxor behavior, ferroelectric properties, crystal structure and microstructure of BT-100xST ceramics have been investigated in detail. As a result, the BT-100xST ceramics with x = 0.20–0.40 present relaxor behavior which was indicated by dielectric constant as a function of temperature and (polarization–electric field) PE hysteresis loops. The BT-30ST ceramics exhibit enhanced electrostrictive coefficient Q33 (>0.034 m4/C2), and the electrostrictive strain and low hysteresis achieves 0.11% and 2%, respectively. The BT-100xST ceramics are considered as a prospective option for application in displacement actuators with high sensitivity and high precision. Full article
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Article
Investigation of the Wear Behavior of Surface Welding AZ91 and AZ91+Gd Alloys under Variable Loading Conditions
Crystals 2021, 11(5), 554; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11050554 - 16 May 2021
Viewed by 492
Abstract
Adding rare earth elements to magnesium alloys is an effective way to improve their wear resistance. However, the effect achieved is closely related to the friction condition. In this paper, two different types of welding wires, AZ91 magnesium alloy and AZ91 + gadolinium [...] Read more.
Adding rare earth elements to magnesium alloys is an effective way to improve their wear resistance. However, the effect achieved is closely related to the friction condition. In this paper, two different types of welding wires, AZ91 magnesium alloy and AZ91 + gadolinium (Gd), were used for surface welding. Dry sliding friction and wear experiments were performed on the surfacing alloys using the pin-on-disc test. The effects of Gd addition on the wear resistance and wear mechanism of the alloy were systematically studied under low to high loads. The results show that as the load increases, the friction coefficient of the surfacing AZ91 alloy gradually decreases as the wear rate increases. A mild–severe wear transition occurred at 100 N. The addition of Gd only slightly increased the wear rate under a load of 15 N. The wear rate was significantly decreased with loads in the range of 30 to 100 N and mild–severe wear transition was avoided. The influence of both Gd addition and load on the wear mechanism were considered. The overall wear resistance of the surfacing magnesium alloy was determined. Full article
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Article
Synthesis, Crystal Structure, DFT Theoretical Calculationand Physico-Chemical Characterization of a New Complex Material (C6H8Cl2N2)2[Cd3Cl10]·6H2O
Crystals 2021, 11(5), 553; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11050553 - 15 May 2021
Viewed by 503
Abstract
The chemical preparation, crystal structure, Hirshfeld surface analysis and spectroscopic characterization of the novel cadmium (II) 2,5-dichloro-p-phenylendiaminium decachlorotricadmate(II) hexahydrate complex, (C6H8Cl2N2)2[Cd3Cl10]·6H2O, has been reported. The [...] Read more.
The chemical preparation, crystal structure, Hirshfeld surface analysis and spectroscopic characterization of the novel cadmium (II) 2,5-dichloro-p-phenylendiaminium decachlorotricadmate(II) hexahydrate complex, (C6H8Cl2N2)2[Cd3Cl10]·6H2O, has been reported. The atomic arrangement can be described as built up by an anionic framework, formed by edge-sharing [CdCl6]2− octahedra in linear polymeric chains spreading along the a-axis, while the organic cations surround these latters. The inspection of the Hirshfeld surface analysis helps to discuss the strength of hydrogen bonds and to quantify the inter-contacts, which reveal that H…Cl/Cl…H (38.9%), H…H (13.9%), and Cd…Cl/Cl…Cd (12.4%) are the main interactions that govern the crystal packing of the studied structure. SEM/EDXwas carried out and the powder XRD confirmed the good crystallinity of the material. FT-IR and the DFT calculation reveal the good correlation between the experimental and the theoretical wavenumbers. The HOMO-LUMO energy gap was used to predict the electric conductivity of the compound. Finally, the thermal TGA/DTA analysis shows stability until 380 K. Full article
(This article belongs to the Section Crystal Engineering)
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Article
Experimental Evaluation of Cement Mortars with End-of-Life Tyres Exposed to Different Surface Treatments
Crystals 2021, 11(5), 552; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11050552 - 15 May 2021
Viewed by 550
Abstract
An end-of-Life Tyre (ELT) is a type of waste that can generate negative social and environmental impacts due to its disposal. Considering that rubber can improve concrete properties and the massive use of concrete as construction material, the addition of ELT rubber in [...] Read more.
An end-of-Life Tyre (ELT) is a type of waste that can generate negative social and environmental impacts due to its disposal. Considering that rubber can improve concrete properties and the massive use of concrete as construction material, the addition of ELT rubber in concrete mixes is attractive. However, concrete mechanical properties are negatively affected due to the rubber-cementitious matrix interaction. Although rubber treatments have been developed to minimise the negative effects, the geo-dependency of the mix makes necessary to find cost-effective and practical solutions that will allow a real use of the ELT waste. Therefore, the objective of the present study is to characterise the properties of cement mortars with the addition of ELT rubber under three surface treatments: hydration, oxidation-sulphonation, and hydrogen peroxide. The results show that hydration is the most favourable treatment from a technical, practical, and economical point of view. In fact, with this treatment, it is possible to add up to 5% ELT rubber, with respect to the aggregate weight, and still exceed the design strength without adding more cement or additives as other investigations. The use of Portland Pozzolana Cement, with local fly ash waste, contributes as well to the promissory results obtained. Full article
(This article belongs to the Special Issue New Frontiers in Cementitious and Lime-Based Materials and Composites)
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Article
Synthesis, Thermal and Optical Characterizations of New Lateral Organic Systems
Crystals 2021, 11(5), 551; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11050551 - 15 May 2021
Cited by 4 | Viewed by 352
Abstract
New laterally OCH3-substituted optical organic Schiff base/ester series, namely 4-(4-(hexyloxyphenyl)iminomethyl)-3-methoxyphenyl 4-alkoxybenzoates, were prepared and characterized with different thermal, mesomorphic, and photoactive techniques. The prepared group constitutes five homologues that differ from each other in the number of carbons in the terminal [...] Read more.
New laterally OCH3-substituted optical organic Schiff base/ester series, namely 4-(4-(hexyloxyphenyl)iminomethyl)-3-methoxyphenyl 4-alkoxybenzoates, were prepared and characterized with different thermal, mesomorphic, and photoactive techniques. The prepared group constitutes five homologues that differ from each other in the number of carbons in the terminal alkoxy chain (n), which varies between n = 6, 8, 10, 12, and 16 carbons. The laterally protruded methoxy group is attached to the central benzene ring that makes an angle of 120° with the molecular long axis. Molecular structures of all newly prepared homologues were fully elucidated via FT-IR, 1H and 13C NMR spectroscopy. Mesomorphic transitions were determined via differential scanning calorimetry (DSC) and the phases identified by polarized optical microscopy (POM). Independent of the length of the terminal alkoxy chain attached to phenyl ester ring, only a monomorphic nematic (N) phase was observed for all the synthesized compounds. A comparative study was made between the present lateral methoxy-substituted homologues and their corresponding laterally-neat analogues. The results revealed that, depending on the length of the alkoxy chain and the presence or absence of the lateral methoxy group, different mesophases with different thermal stability and temperature ranges were observed. Finally, UV-vis spectra showed that the present nematogenic series possess photoactive properties that are of importance for many applications. Full article
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Article
Enhancement of Optical Activity and Properties of Barium Titanium Oxides to Be Active in Sunlight through Using Hollandite Phase Instead of Perovskite Phase
Crystals 2021, 11(5), 550; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11050550 - 15 May 2021
Viewed by 435
Abstract
The present study aims to enhance the optical properties of barium titanate through narrowing its band gap energy to be effective for photocatalytic reactions in sunlight and be useful for solar cells. This target was achieved through growth of the hollandite phase instead [...] Read more.
The present study aims to enhance the optical properties of barium titanate through narrowing its band gap energy to be effective for photocatalytic reactions in sunlight and be useful for solar cells. This target was achieved through growth of the hollandite phase instead of the perovskite phase inside the barium titanate crystals. By using solvent thermal reactions and thermal treatment at different temperatures (250 °C, 600 °C, and 900 °C), the hollandite phase of barium titanate was successfully obtained and confirmed through X-ray diffraction (XRD), Raman spectra and scanning electron microscopy techniques. XRD patterns showed a clear hollandite phase of barium titanium oxides for the sample calcined at 900 °C (BT1-900); however, the samples at 600 °C showed the presence of mixed phases. The mean crystallite size of the BT1-900 sample was found to be 38 nm. Morphological images revealed that the hollandite phase of barium titanate consisted of a mixed morphology of spheres and sheet-like features. The optical properties of barium titanate showed that its absorption edge shifted to the visible region and indicated band gap energy tuning ranging from 1.75 eV to 2.3 eV. Photocatalytic studies showed the complete and fast decolorization and mineralization of green pollutants (naphthol green B; NGB) in the prepared barium titanate with hollandite phase after illumination in sunlight for ten minutes. Finally, it can be concluded that the low band gap energy of barium titanate having the hollandite phase introduces beneficial structures for optical applications in sunlight. Full article
(This article belongs to the Special Issue New Trends in Crystals at Saudi Arabia)
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Article
Influences of Process Parameters on the Microstructure and Mechanical Properties of CoCrFeNiTi Based High-Entropy Alloy in a Laser Powder Bed Fusion Process
Crystals 2021, 11(5), 549; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11050549 - 14 May 2021
Viewed by 556
Abstract
Recently, high-entropy alloys (HEAs) have attracted much attention because of their superior properties, such as high strength and corrosion resistance. This study aimed to investigate the influences of process parameters on the microstructure and mechanical properties of CoCrFe NiTiMo HEAs using a laser-based [...] Read more.
Recently, high-entropy alloys (HEAs) have attracted much attention because of their superior properties, such as high strength and corrosion resistance. This study aimed to investigate the influences of process parameters on the microstructure and mechanical properties of CoCrFe NiTiMo HEAs using a laser-based powder bed fusion (LPBF) process. In terms of laser power and scan speed, a process map was constructed by evaluating the density and surface roughness of the as-built specimen to optimize the process parameters of the products. The mechanical properties of the as-built specimens fabricated at the optimum fabrication condition derived from the process map were evaluated. Consequently, the optimum laser power and scan speed could be obtained using the process map evaluated by density and surface roughness. The as-built specimen fabricated at the optimum fabrication condition presented a relative density of more than 99.8%. The microstructure of the as-built specimen exhibited anisotropy along the build direction. The tensile strength and elongation of the as-built specimen were around 1150 MPa and more than 20%, respectively. Full article
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Article
A Systematic Study of Compositionally Dependent Dielectric Tensors of SnSxSe1-x Alloys by Spectroscopic Ellipsometry
Crystals 2021, 11(5), 548; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11050548 - 14 May 2021
Viewed by 436
Abstract
We report the dielectric tensors on the cleavage plane of biaxial SnSxSe1-x alloys in the spectral energy region from 0.74 to 6.42 eV obtained by spectroscopic ellipsometry. Single-crystal SnSxSe1-x alloys were grown by the temperature-gradient [...] Read more.
We report the dielectric tensors on the cleavage plane of biaxial SnSxSe1-x alloys in the spectral energy region from 0.74 to 6.42 eV obtained by spectroscopic ellipsometry. Single-crystal SnSxSe1-x alloys were grown by the temperature-gradient method. Strongly anisotropic optical responses are observed along the different principal axes. An approximate solution yields the anisotropic dielectric functions along the zigzag (a-axis) and armchair (b-axis) directions. The critical point (CP) energies of SnSxSe1-x alloys are obtained by analyzing numerically calculated second derivatives, and their physical origins are identified by energy band structure. Blue shifts of the CPs are observed with increasing S composition. The fundamental bandgap for Se = 0.8 and 1 in the armchair axis arises from band-to-band transitions at the M0 minimum point instead of the M1 saddle point as in SnS. These optical data will be useful for designing optoelectronic devices based on SnSxSe1-x alloys. Full article
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Article
A Study of Interfacial Electronic Structure at the CuPc/CsPbI2Br Interface
Crystals 2021, 11(5), 547; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11050547 - 14 May 2021
Viewed by 475
Abstract
In this article, CsPbI2Br perovskite thin films were spin-coated on FTO, on which CuPc was deposited by thermal evaporation. The electronic structure at the CsPbI2Br/CuPc interface was examined during the CuPc deposition by in situ X-ray photoelectron spectroscopy (XPS) [...] Read more.
In this article, CsPbI2Br perovskite thin films were spin-coated on FTO, on which CuPc was deposited by thermal evaporation. The electronic structure at the CsPbI2Br/CuPc interface was examined during the CuPc deposition by in situ X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS) measurements. No downward band bending was resolved at the CsPbI2Br side, whereas there is ~0.23 eV upward band bending as well as a dipole of ~0.08 eV identified at the molecular side. Although the hole injection barrier as indicated by the energy gap from CsPbI2Br valance band maximum (VBM) to CuPc highest occupied molecular orbital (HOMO) was estimated to be ~0.26 eV, favoring hole extraction from CsPbI2Br to CuPc, the electron blocking barrier of ~0.04 eV as indicated by the offset between CsPbI2Br conduction band minimum (CBM) and CuPc lowest unoccupied molecular orbital (LUMO) is too small to efficiently block electron transfer. Therefore, the present experimental study implies that CuPc may not be a promising hole transport material for high-performance solar cells using CsPbI2Br as active layer. Full article
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Article
Xenon Plasma Focused Ion Beam Milling for Obtaining Soft X-ray Transparent Samples
Crystals 2021, 11(5), 546; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11050546 - 14 May 2021
Viewed by 529
Abstract
We employ xenon (Xe) plasma focused ion beam (PFIB) milling to obtain soft X-ray transparent windows out of bulk samples. The use of a Xe PFIB allows for the milling of thin windows (several 100 nm thick) with areas of the order of [...] Read more.
We employ xenon (Xe) plasma focused ion beam (PFIB) milling to obtain soft X-ray transparent windows out of bulk samples. The use of a Xe PFIB allows for the milling of thin windows (several 100 nm thick) with areas of the order of 100 µm × 100 µm into bulk substrates. In addition, we present an approach to empirically determine the transmission level of such windows during fabrication by correlating their electron and soft X-ray transparencies. We perform scanning transmission X-ray microscopy (STXM) imaging on a sample obtained by Xe PFIB milling to demonstrate the conceptual feasibility of the technique. Our thinning approach provides a fast and simplified method for facilitating soft X-ray transmission measurements of epitaxial samples and it can be applied to a variety of different sample systems and substrates that are otherwise not accessible. Full article
(This article belongs to the Special Issue Advanced Imaging Methods)
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Article
Experimental Study of Plasma Plume Analysis of Long Pulse Laser Irradiates CFRP and GFRP Composite Materials
Crystals 2021, 11(5), 545; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11050545 - 13 May 2021
Viewed by 478
Abstract
The application of laser fabrication of fiber-reinforced polymer (FRP) has an irreplaceable advantage. However, the effect of the plasma generated in laser fabrication on the damage process is rarely mentioned. In order to further study the law and mechanism of laser processing, the [...] Read more.
The application of laser fabrication of fiber-reinforced polymer (FRP) has an irreplaceable advantage. However, the effect of the plasma generated in laser fabrication on the damage process is rarely mentioned. In order to further study the law and mechanism of laser processing, the laser process was measured. CFRP and GFRP materials were damaged by a 1064 nm millisecond pulsed laser. Moreover, the propagation velocity and breakdown time of plasma plume were compared. The results show that GFRP is more vulnerable to breakdown than CFRP under the same conditions. In addition, the variation of plasma plume and material surface temperature with the number of pulses was also studied. The results show that the variation trend is correlated, that is, the singularities occur at the second pulse. Based on the analysis of experimental phenomena, this paper provides guidance for plasma phenomena in laser processing of composite materials. Full article
(This article belongs to the Special Issue Advances in Middle Infrared Laser Crystals and Its Applications)
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Article
Anisotropy of X-ray Absorption Cross Section in CeCoGe3 Single Crystal
Crystals 2021, 11(5), 544; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11050544 - 13 May 2021
Viewed by 545
Abstract
Absorption spectra of two orthogonal linearly polarized X-rays in a single CeCoGe3 crystal were measured at the ID12 beamline of the ESRF for the energies near the K-edges of Ge, Co and near the L23 edges of Ce. The X-ray natural [...] Read more.
Absorption spectra of two orthogonal linearly polarized X-rays in a single CeCoGe3 crystal were measured at the ID12 beamline of the ESRF for the energies near the K-edges of Ge, Co and near the L23 edges of Ce. The X-ray natural linear dichroism (XNLD) was revealed in the vicinity of all the absorption edges, which indicates a splitting of electronic states in a crystalline field. Mathematical modelling in comparison with experimental data allowed the isotropic and anisotropic parts of atomic absorption cross section in CeCoGe3 to be determined near all measured absorption edges. The calculations also show that the “average” anisotropy of the cross section close to the Ge K-edge revealed in the experiment is less than the partial anisotropic contributions corresponding to Ge atoms in two different Wyckoff positions. Full article
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Article
SiC3 as a Charge-Regulated Material for CO2 Capture
Crystals 2021, 11(5), 543; https://0-doi-org.brum.beds.ac.uk/10.3390/cryst11050543 - 13 May 2021
Viewed by 482
Abstract
The increasing CO2 emission rate is deteriorating the atmospheric environment, leading to global warming and climate change. The potential of the SiC3 nanosheet as a functioning material for the separation of CO2 from the mixture of CO2, H [...] Read more.
The increasing CO2 emission rate is deteriorating the atmospheric environment, leading to global warming and climate change. The potential of the SiC3 nanosheet as a functioning material for the separation of CO2 from the mixture of CO2, H2, N2 and CH4 by injecting negative charges is studied by DFT calculations in this paper. The results show that in the absence of injecting negative charges, CO2 interacts weakly with the SiC3 nanosheet. While the interaction between CO2 and the SiC3 nanosheet can be strengthened by the injection of negative charges, the absorption mechanism of CO2 changes from physisorption to chemisorption when the injection of negative charges is switched on. H2/N2/CH4 are all physiosorbed on the SiC3 nanosheet with/without the injection of negative charges. The mechanism of CO2 adsorption/desorption on the SiC3 nanosheet could be tuned by switching on/off the injection of negative charges. Our results indicate that the SiC3 nanosheet can be regarded as a charge-regulated material for the separation of CO2 from the CO2/H2/N2/CH4 mixture. Full article
(This article belongs to the Special Issue 2D Crystalline Monolayer Nanosheets)
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