Research

12 pages, 3319 KiB

Open AccessArticle

On the Deposition Process of Ceramic Layer Thin Films for Low-Carbon Steel Pipe Protection

by Stefan Irimiciuc, Marius Gabriel Zaharia, Ramona Cimpoesu, Georgiana Bulai, Silviu Octavian Gurlui and Nicanor Cimpoesu

Materials 2022, 15(13), 4673; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15134673 - 03 Jul 2022

Cited by 1 | Viewed by 1429

Abstract

Ceramic thin films with variable thicknesses have been used in many applications. In order to protect the petroleum transportation pipes against the harmful H₂S action, two ceramic materials as thin layers are proposed. In this article, pulsed laser deposition (PLD) of [...] Read more.

Ceramic thin films with variable thicknesses have been used in many applications. In order to protect the petroleum transportation pipes against the harmful H₂S action, two ceramic materials as thin layers are proposed. In this article, pulsed laser deposition (PLD) of ceramic layers by in situ time-resolved optical techniques is investigated. Two ceramic materials were used as targets and real-time monitoring of the PLD process was realized via ICCD fast camera imaging and optical emission spectroscopy. The space–time displacement of the ceramic emissions was analyzed in order to determine the plasma structure and respective kinetic energies. Spectral-resolved investigation allowed the determination of plasma species individual velocities (in the first case: 43 km/s for C ionic species, 11 km/s for Si, from 25 to 5 km/s for atomic species; in the second case: 32 km/s for C ionic species, 11 km/s for W species, and 15 and 53 km/s for neutral species). SEM and AFM techniques were implemented to analyze the resulting ceramic layers showing homogeneous surfaces with characteristic material droplets. The ablation crater also reveals selective ablation during the deposition process. EDX results show that Al/Si is retained in the thin films similar to the target composition. Full article

(This article belongs to the Special Issue Laser Ablation: Materials and Applications)

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16 pages, 2527 KiB

Open AccessArticle

Concentration Quantification of TiO₂ Nanoparticles Synthesized by Laser Ablation of a Ti Target in Water

by Damjan Blažeka, Julio Car and Nikša Krstulović

Materials 2022, 15(9), 3146; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15093146 - 26 Apr 2022

Cited by 7 | Viewed by 1727

Abstract

In this work, we present a quantitative method for determining the concentration of metal oxide nanoparticles (NP) synthesized by laser ablation in liquid. The case study was performed with titanium dioxide nanoparticles (TiO₂ NP), which were synthesized by laser ablation of a [...] Read more.

In this work, we present a quantitative method for determining the concentration of metal oxide nanoparticles (NP) synthesized by laser ablation in liquid. The case study was performed with titanium dioxide nanoparticles (TiO₂ NP), which were synthesized by laser ablation of a Ti target in water. After synthesis, a colloidal solution was analyzed with UV-Vis spectroscopy. At the same time, the craters that remained on the Ti target after ablation were evaluated with an optical microscope to determine the volume of the ablated material. SEM microscopy was used to determine the TiO₂ NP size distribution. It was found that synthesized TiO₂ NP followed a Log-Normal diameter distribution with a maximum at about 64 nm. From the volume of ablated material and NP size distribution, under the assumption that most of the ablated material is consumed to form nanoparticles, a concentration of nanoparticles can be determined. The proposed method is verified by comparing the calculated concentrations to the values obtained from the Beer–Lambert law using the Mie scattering theory for the NP cross-section calculation. Full article

(This article belongs to the Special Issue Laser Ablation: Materials and Applications)

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22 pages, 8710 KiB

Open AccessArticle

Study of Micro/Nano Structuring and Mechanical Properties of KrF Excimer Laser Irradiated Al for Aerospace Industry and Surface Engineering Applications

by Umm-i-Kalsoom, Nisar Ali, Shazia Bashir, Ali Mohammad Alshehri and Narjis Begum

Materials 2021, 14(13), 3671; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14133671 - 30 Jun 2021

Cited by 13 | Viewed by 1905

Abstract

Micro/nano structuring of KrF Excimer laser-irradiated Aluminum (Al) has been correlated with laser-produced structural and mechanical changes. The effect of non-reactive Argon (Ar) and reactive Oxygen (O₂) environments on the surface, structural and mechanical characteristics of nano-second pulsed laser-ablated Aluminum (Al) [...] Read more.

Micro/nano structuring of KrF Excimer laser-irradiated Aluminum (Al) has been correlated with laser-produced structural and mechanical changes. The effect of non-reactive Argon (Ar) and reactive Oxygen (O₂) environments on the surface, structural and mechanical characteristics of nano-second pulsed laser-ablated Aluminum (Al) has been revealed. KrF Excimer laser with pulse duration 20 ns, central wavelength of 248 nm and repetition rate of was utilized for this purpose. Exposure of targets has been carried out for 0.86, 1, 1.13 and 1.27 J^·cm⁻² laser fluences in non-reactive (Ar) and reactive (O₂) ambient environments at a pressure of 100 torr. A variety of characteristics of the irradiated targets like the morphology of the surface, chemical composition, crystallinity and nano hardness were investigated by using Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Energy Dispersive X-ray Spectroscopy (EDS), X-ray Diffractometer (XRD), Raman spectroscopy and Nanohardness tester techniques, respectively. The nature (reactive or non-reactive) and pressure of gas played an important role in modification of materials. In this study, a strong correlation is observed between the surface structuring, chemical composition, residual stress variation and the variation in hardness of Al surface after ablation in both ambient (Ar, O₂). In the case of reactive environment (O₂), the interplay among the deposition of laser energy and species of plasma of ambient gas enhances chemical reactivity, which causes the formation of oxides of aluminum (AlO, Al₂O₃) with high mechanical strength. That makes it useful in the field of process and aerospace industry as well as in surface engineering. Full article

(This article belongs to the Special Issue Laser Ablation: Materials and Applications)

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13 pages, 4653 KiB

Open AccessArticle

Effects of Different Surfactant Charges on the Formation of Gold Nanoparticles by the LASiS Method

by Muhammad Zulfajri, Wei-Jie Huang, Genin-Gary Huang and Hui-Fen Chen

Materials 2021, 14(11), 2937; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14112937 - 29 May 2021

Cited by 6 | Viewed by 2052

Abstract

The laser ablation synthesis in solution (LASiS) method has been widely utilized due to its significant prospects in laser microprocessing of nanomaterials. In this study, the LASiS method with the addition of different surfactant charges (cationic CTAB, nonionic TX-100, and anionic SDS) was [...] Read more.

The laser ablation synthesis in solution (LASiS) method has been widely utilized due to its significant prospects in laser microprocessing of nanomaterials. In this study, the LASiS method with the addition of different surfactant charges (cationic CTAB, nonionic TX-100, and anionic SDS) was used to produce Au NPs. An Nd:YAG laser system at 532 nm excitation with some synthetic parameters, including different laser fluences, ablation times, and surfactant concentrations was performed. The obtained Au NPs were characterized by UV-Vis spectroscopy, transmission electron microscopy, and zeta potential analyzer. The Au NPs exhibited the maximum absorption peak at around 520 nm for all samples. The color of Au NPs was changed from red to reddish by increasing the laser fluence. The surfactant charges also played different roles in the Au NPs’ growth during the synthesis process. The average sizes of Au NPs were found to be 8.5 nm, 5.5 nm, and 15.5 nm with the medium containing CTAB, TX-100, and SDS, respectively. Besides, the different surfactant charges induced different performances to protect Au NPs from agglomeration. Overall, the SDS and CTAB surfactants exhibited higher stability of the Au NPs compared to the Au NPs with TX-100 surfactant. Full article

(This article belongs to the Special Issue Laser Ablation: Materials and Applications)

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14 pages, 3227 KiB

Open AccessArticle

The Effect of Confinement Angle on Self-Colliding Aluminium Laser Plasmas Using Spectrally Resolved Fast Imaging

by Lazaros Varvarezos, Stephen J. Davitt, John T. Costello and Thomas J. Kelly

Materials 2020, 13(23), 5489; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13235489 - 02 Dec 2020

Cited by 1 | Viewed by 1650

Abstract

In this work we investigate the effect of the confinement angle on self-colliding aluminium laser produced plasmas. More specifically, we apply V-shaped channel targets of different angles (90°, 60° and 30°) and report both broadband and filtered time-resolved fast imaging measurements on the [...] Read more.

In this work we investigate the effect of the confinement angle on self-colliding aluminium laser produced plasmas. More specifically, we apply V-shaped channel targets of different angles (90°, 60° and 30°) and report both broadband and filtered time-resolved fast imaging measurements on the formation of such plasmas in ambient air. Based on the broadband measurements we suggest that the plasmas formed on the two inner walls of the V-shaped channel expand normally to the surface, interact with each other and possibly stagnate. The spectrally filtered fast imaging reveals the presence of a spatial distribution of different species within the plasmas and signatures of forced recombination. Full article

(This article belongs to the Special Issue Laser Ablation: Materials and Applications)

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15 pages, 3403 KiB

Open AccessArticle

Photodegradation of Methylene Blue and Rhodamine B Using Laser-Synthesized ZnO Nanoparticles

by Damjan Blažeka, Julio Car, Nikola Klobučar, Andrea Jurov, Janez Zavašnik, Andrea Jagodar, Eva Kovačević and Nikša Krstulović

Materials 2020, 13(19), 4357; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13194357 - 30 Sep 2020

Cited by 44 | Viewed by 3057

Abstract

In this paper we examined the photocatalytic efficiency of a laser-synthesized colloidal solution of ZnO nanoparticles synthesized by laser ablation in water. The average size of the obtained colloidal ZnO nanoparticles is about 47 nm. As revealed by electron microscopy, other nanostructures were [...] Read more.

In this paper we examined the photocatalytic efficiency of a laser-synthesized colloidal solution of ZnO nanoparticles synthesized by laser ablation in water. The average size of the obtained colloidal ZnO nanoparticles is about 47 nm. As revealed by electron microscopy, other nanostructures were also present in the colloidal solution, especially nanosheets. A photocatalytic degradation of UV-irradiated Methylene Blue and Rhodamine B solutions of different concentration in the presence of different ZnO catalyst mass concentrations was studied in order to examine their influence on photodegradation rates. ZnO nanoparticles have shown high photocatalytic efficiency, which is limited due to different effects related to UV light transmittivity through the colloidal solution. Therefore, increasing catalyst concentration is effective way to increase photocatalytic efficiency up to some value where photodegradation rate saturation occurs. The photodegradation rate increases as the dye concentration decreases. These findings are important for water purification applications of laser-synthesized ZnO nanoparticles. Full article

(This article belongs to the Special Issue Laser Ablation: Materials and Applications)

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14 pages, 5526 KiB

Open AccessArticle

Laser-Assisted Synthesis of Composite Nanoparticles of Perovskite BaTiO₃ in Aqueous Solutions and Their Optical Properties

by Ekaterina V. Barmina, Bulat A. Mukhametyanov, Oleg V. Uvarov, Igor I. Vlasov, Oleg S. Kudryavtsev, Yurii L. Kalachev, Evangelos Skoulas, George Kourmoulakis, Valeriy V. Voronov, Emmanuel Stratakis and Georgy A. Shafeev

Materials 2020, 13(18), 4086; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13184086 - 14 Sep 2020

Cited by 2 | Viewed by 2428

Abstract

Experimental results are presented on laser-assisted synthesis of composite nanoparticles of perovskite BaTiO₃ with gold nanoparticles using the technique of laser ablation in water and aqueous solution of hydrogen peroxide. Nanoparticles of BaTiO₃ are generated by near IR laser radiation with [...] Read more.

Experimental results are presented on laser-assisted synthesis of composite nanoparticles of perovskite BaTiO₃ with gold nanoparticles using the technique of laser ablation in water and aqueous solution of hydrogen peroxide. Nanoparticles of BaTiO₃ are generated by near IR laser radiation with pulse durations of 170 fs, 1 ps, and 200 ns. Nanoparticles of barium titanate BaTiO₃ (BTO) have tetragonal structure for all used pulse durations. Two ways of synthesis are tested. In the first one a gold target is ablated in the colloidal solution of BaTiO₃ nanoparticles. The second way consists of laser exposure of the mixture of colloidal solutions of nanoparticles of BaTiO₃ and Au. Synthesized composite nanoparticles are characterized by optical spectroscopy, Raman spectroscopy, X-Ray diffractometry, and Transmission Electron Microscopy. Composite BaTiO₃‑Au nanoparticles have the absorption band in the visible range of spectrum and demonstrate plasmonic luminescence. Full article

(This article belongs to the Special Issue Laser Ablation: Materials and Applications)

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21 pages, 3311 KiB

Open AccessArticle

Bacteria Exposed to Silver Nanoparticles Synthesized by Laser Ablation in Water: Modelling E. coli Growth and Inactivation

by Lucija Krce, Matilda Šprung, Ana Maravić, Polona Umek, Krešimir Salamon, Nikša Krstulović and Ivica Aviani

Materials 2020, 13(3), 653; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13030653 - 01 Feb 2020

Cited by 18 | Viewed by 4341

Abstract

This study is aimed to better understand the bactericidal mode of action of silver nanoparticles. Here we present the production and characterization of laser-synthesized silver nanoparticles along with growth curves of bacteria treated at sub-minimal and minimal inhibitory concentrations, obtained by optical density [...] Read more.

This study is aimed to better understand the bactericidal mode of action of silver nanoparticles. Here we present the production and characterization of laser-synthesized silver nanoparticles along with growth curves of bacteria treated at sub-minimal and minimal inhibitory concentrations, obtained by optical density measurements. The main effect of the treatment is the increase of the bacterial apparent lag time, which is very well described by the novel growth model as well as the entire growth curves for different concentrations. The main assumption of the model is that the treated bacteria uptake the nanoparticles and inactivate, which results in the decrease of both the nanoparticles and the bacteria concentrations. The lag assumes infinitive value for the minimal inhibitory concentration treatment. This apparent lag phase is not postponed bacterial growth. It is a dynamic state in which the bacterial growth and death rates are close in value. Our results strongly suggest that the predominant mode of antibacterial action of silver nanoparticles is the penetration inside the membrane. Full article

(This article belongs to the Special Issue Laser Ablation: Materials and Applications)

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