Crystals

11 pages, 2354 KiB

Open AccessArticle

Differential Frequency Exploration of Vortex Light in Lithium Niobate Crystals

by Xing Wei, Samuel Kesse and Ballipalli Chandra Babu

Crystals 2023, 13(1), 154; https://doi.org/10.3390/cryst13010154 - 16 Jan 2023

Viewed by 2204

In recent years, Orbital Angular Momentum (OAM) beams have been applied in optical communications to improve channel capacity and spectral efficiency. However, in practical applications, OAM information is often imprinted on short-wavelength light beams. How to completely transfer this information to the O-band [...] Read more.

In recent years, Orbital Angular Momentum (OAM) beams have been applied in optical communications to improve channel capacity and spectral efficiency. However, in practical applications, OAM information is often imprinted on short-wavelength light beams. How to completely transfer this information to the O-band to achieve long-distance transmission has not been conveniently achieved through most traditional methods. We studied the differential frequency experiment of OAM-carrying beams from both theoretical and experimental facets. In the periodic polarization 0 class matched lithium niobate crystal, the difference in frequency between the incident 1950 nm strong pump light and the 780 nm weak input light is achieved, resulting in output light in the O band. The polarization period of the crystal is 20 μm, and the best phase matching is achieved when the temperature is maintained at 41.2 °C. At this time, 780 nm vortex light produces 1300 nm vortex light, and the nonlinear conversion efficiency reaches 0.1387% (topological charge number l = 5). During the experiment, momentum, energy, and topological charge are all conserved. Our experiment successfully converted vortex light at 780 nm into vortex light at 1300 nm, paving the way for the subsequent conversion of 780 nm single photons generated by quantum dots carrying OAM into OAM photons in the communication band. Full article

(This article belongs to the Special Issue Optical Field Modulation Based on Liquid Crystals and Beyond)

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13 pages, 2793 KiB

Open AccessArticle

Computational Studies on the Interaction of Organophosphorus Pesticides with Acetylcholinesterase and Butyrylcholinesterase: Quantum Chemical Cluster Model and HSAB Approaches

by Shu-Chun Chi and Chia Ming Chang

Crystals 2023, 13(1), 153; https://doi.org/10.3390/cryst13010153 - 16 Jan 2023

Viewed by 2105

Abstract

In the present study, the interaction between organophosphorus pesticides and cholinesterase enzymes was investigated by quantum chemical cluster model and hard-soft acid-base (HSAB) approaches. The computational results of the equilibrium structure and reaction enthalpy were used to decipher the mechanism of organophosphorus pesticides [...] Read more.

In the present study, the interaction between organophosphorus pesticides and cholinesterase enzymes was investigated by quantum chemical cluster model and hard-soft acid-base (HSAB) approaches. The computational results of the equilibrium structure and reaction enthalpy were used to decipher the mechanism of organophosphorus pesticides coumaphos, dicrotophos, phorate, and terbufos, which interacted with the molecular cluster models of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes. In addition, the HOMO-LUMO energy gap and the HSAB descriptors prove that AChE has outstanding electron acceptability, which is suitable as a biosensing material. In terms of the calculated electronic spectrum, because the energy level of the ground state and the excited state are changed after adding pesticides with enzymes, a significant red shift phenomenon will occur. Full article

(This article belongs to the Special Issue Theoretical Investigation on Non-covalent Interactions)

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13 pages, 3730 KiB

Open AccessArticle

Evaluation of La_1−xSr_xNi_0.4Fe_0.6O_3-δ as Electrode Materials for Direct Methane Symmetrical Solid Oxide Fuel Cells

by Caixia Shi, Ting Chen, Dongyang Fang and Shaorong Wang

Crystals 2023, 13(1), 152; https://doi.org/10.3390/cryst13010152 - 15 Jan 2023

Viewed by 2058

Abstract

In this work, La_1−xSr_xNi_0.4Fe_0.6O_3-δ (0 ≤ x ≤ 0.2) oxides were synthesized and employed as the identical electrode of direct methane symmetrical solid oxide fuel cell (SSOFC). In addition, the phase structure, redox stability, [...] Read more.

In this work, La_1−xSr_xNi_0.4Fe_0.6O_3-δ (0 ≤ x ≤ 0.2) oxides were synthesized and employed as the identical electrode of direct methane symmetrical solid oxide fuel cell (SSOFC). In addition, the phase structure, redox stability, electrical conductivity, chemical compatibility, and thermal expansion of La_1−xSr_xNi_0.4Fe_0.6O_3-δ oxides were evaluated. The La₂NiO₄ phase occurs when the amount of doped Sr rises to 0.2. The composition of La_0.9Sr_0.1Ni_0.4Fe_0.6O_3-δ (LSNF9146) boasts the highest conductivity of 463 S cm⁻¹ with lowest activation energy of 0.066 eV as well as a relatively large thermal expansion coefficient. After treatment in methane for 10 h, the LSNF9146 oxide exhibits 33% lower carbon deposition than the LaNi_0.4Fe_0.6O_3-δ (LNF46) oxide. Moreover, the impregnated LSNF9146 electrode demonstrates lower polarization resistance in both air and methane atmospheres. SSOFCs with impregnated LSNF9146 and LNF46 identical composite electrodes have the maximum power densities of 233 and 170 mW cm⁻² at 850 °C in methane, respectively. These results prove that LSNF9146 is a promising symmetrical electrode with high catalytic activity, good redox stability, and coking resistance to direct methane SSOFCs. Full article

(This article belongs to the Special Issue Advances of Solid Oxide Fuel Cells)

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20 pages, 5021 KiB

Open AccessArticle

Study on Grinding Force of Two-Dimensional Ultrasonic Vibration Grinding 2.5D-C/SiC Composite Material

by Yunguang Zhou, Chuanchuan Tian, Shiqi Jia, Lianjie Ma, Guoqiang Yin and Yadong Gong

Crystals 2023, 13(1), 151; https://doi.org/10.3390/cryst13010151 - 15 Jan 2023

Cited by 11 | Viewed by 2416

Abstract

The grinding force is an important index during the grinding process, which affects the surface quality and other aspects after machining. However, the research on the grinding force of ceramic matrix composites assisted by two-dimensional ultrasonic vibration-assisted grinding is very weak. In this [...] Read more.

The grinding force is an important index during the grinding process, which affects the surface quality and other aspects after machining. However, the research on the grinding force of ceramic matrix composites assisted by two-dimensional ultrasonic vibration-assisted grinding is very weak. In this paper, the impact of the relationship between the critical cutting depth and the maximum undeformed chip thickness on the removal mode of ceramic matrix composites was analyzed. On this basis, the grinding force model of two-dimensional ultrasonic vibration-assisted grinding were developed for ductile removal and brittle removal, respectively. Finally, the correctness of the model was verified, and the impact of grinding parameters on the grinding force was analyzed. The experimental results show that compared with the conventional grinding force, the two-dimensional ultrasonic vibration assisted grinding force decreases obviously. When the feed rate and grinding depth increase, the grinding force increases. When the grinding velocity and ultrasonic amplitude increase, the grinding force decreases. Compared with the experimental value, the average relative error of normal grinding force is 8.49%, and the average relative error of tangential grinding force is 13.59%. The experimental and theoretical values of the grinding force have a good fitting relationship. Full article

(This article belongs to the Special Issue Processing Technology of Brittle Crystal Materials)

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10 pages, 3861 KiB

Open AccessArticle

Solid State Structure and Hydrogen Bonding of Some Cyclic NH Carboximides

by R. Alan Aitken, Alexander J. B. Nelson, Alexandra M. Z. Slawin and Dheirya K. Sonecha

Crystals 2023, 13(1), 150; https://doi.org/10.3390/cryst13010150 - 15 Jan 2023

Viewed by 1590

Abstract

Thirteen new crystal structures of cyclic NH carboximides have been determined and are compared with respect to the mode of intermolecular hydrogen bonding observed in the crystal. The structures include a new cyclobutane-fused succinimide, seven new simple bi- and tricyclic succinimides derived from [...] Read more.

Thirteen new crystal structures of cyclic NH carboximides have been determined and are compared with respect to the mode of intermolecular hydrogen bonding observed in the crystal. The structures include a new cyclobutane-fused succinimide, seven new simple bi- and tricyclic succinimides derived from Diels–Alder reactions of maleimide, three methylated glutarimides, a morpholinedione and adipimide, the first seven-membered ring NH carboximide to be structurally characterised. Overall, seven of the compounds adopt a ribbon structure, five show centrosymmetric dimers, and one has bonding between NH and a remote bridging ether oxygen. Halogen bonding was also detected in one case. Full article

(This article belongs to the Special Issue Feature Papers in Crystal Engineering in 2022)

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10 pages, 1748 KiB

Open AccessArticle

A Rare Structural Motif for a Luminescent Cu(I) Coordination Polymer with 3-(Pyridin-2-yl)triimidazotriazine

by Daniele Malpicci, Delia Blasi, Daniele Marinotto, Alessandra Forni, Elena Cariati, Elena Lucenti and Lucia Carlucci

Crystals 2023, 13(1), 149; https://doi.org/10.3390/cryst13010149 - 14 Jan 2023

Cited by 4 | Viewed by 2054

Abstract

The coordination ability of the pyridine derivative of cyclic triimidazole, namely 3-(pyridin-2-yl)triimidazotriazine (TT-Py) towards Cu(I) was explored. TT-Py is an appealing nitrogen-rich ligand characterized by the presence of three imidazole nitrogen atoms with trigonal symmetry and a pyridine moiety, available for [...] Read more.

The coordination ability of the pyridine derivative of cyclic triimidazole, namely 3-(pyridin-2-yl)triimidazotriazine (TT-Py) towards Cu(I) was explored. TT-Py is an appealing nitrogen-rich ligand characterized by the presence of three imidazole nitrogen atoms with trigonal symmetry and a pyridine moiety, available for coordination to metal ions. The multidentate nature of TT-Py allows to isolate, by reaction with CuI at room temperature, the one-dimensional coordination network [Cu₂I₂(TT-Py)]_n (1). 1 is characterized by a rare structural network built-up by the combination in a 1:2 ratio of two common motifs for Cu(I) halides coordination polymers, which are the double-stranded stair and the zig-zag chain. 1 displays one broad long-lived emission in the solid state, which has been associated, by the support of DFT and TDDFT calculation, with low-energy transitions of MLCT or XMLCT character. Full article

(This article belongs to the Special Issue Multifunctional Coordination Polymers: Synthesis, Structure, Properties and Applications)

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9 pages, 2030 KiB

Open AccessCommunication

Raman- and Infrared-Active Phonons in Nonlinear Semiconductor AgGaGeS₄

by Mykhailo Valakh, Alexander P. Litvinchuk, Yevhenii Havryliuk, Volodymyr Yukhymchuk, Volodymyr Dzhagan, Dmytro Solonenko, Sergei A. Kulinich, Lyudmyla Piskach, Yuriy Kogut, Lu He and Dietrich R. T. Zahn

Crystals 2023, 13(1), 148; https://doi.org/10.3390/cryst13010148 - 14 Jan 2023

Cited by 1 | Viewed by 1983

Abstract

AgGaGeS₄ is an emerging material with promising nonlinear properties in the near- and mid-infrared spectral ranges. Here, the experimental phonon spectra of AgGaGeS₄ single crystals synthesized by a modified Bridgman method are presented. The infrared absorption spectra are reported. They are [...] Read more.

AgGaGeS₄ is an emerging material with promising nonlinear properties in the near- and mid-infrared spectral ranges. Here, the experimental phonon spectra of AgGaGeS₄ single crystals synthesized by a modified Bridgman method are presented. The infrared absorption spectra are reported. They are obtained from the fitting of reflectivity to a model dielectric function comprising a series of harmonic phonon oscillators. In the Raman spectra, several modes are registered, which were not detected in previous works. The analysis of the experimental vibrational bands is performed on the basis of a comparison with reported data on structurally related binary, ternary, and quaternary metal chalcogenides. The temperature dependence of the Raman spectra between room temperature and 15 K is also investigated. Full article

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17 pages, 10577 KiB

Open AccessEditor’s ChoiceArticle

Simplified Approach to Characterize the Cooling Crystallization in a Modular Mini-Plant

by Stefan Höving, Phil Bolien, Paul Siebers and Norbert Kockmann

Crystals 2023, 13(1), 147; https://doi.org/10.3390/cryst13010147 - 14 Jan 2023

Cited by 2 | Viewed by 2051

Abstract

The characterization of new process equipment often includes tedious experiments, particularly for (cooling) crystallization. This can be cost-intensive and time-consuming when the actual equipment has to be continuously operated to gain new insights. For multi-purpose plants that frequently change the process substance system, [...] Read more.

The characterization of new process equipment often includes tedious experiments, particularly for (cooling) crystallization. This can be cost-intensive and time-consuming when the actual equipment has to be continuously operated to gain new insights. For multi-purpose plants that frequently change the process substance system, this can be especially laborious. In order to accelerate the generation of characterization data for the quasi-continuous filter belt crystallizer (QCFBC), a Peltier-element-driven, simplified experimental benchtop setup is validated in this work using a sucrose/water model substance system. It was shown that the operation conditions during the cooling crystallization on the continuously operated plant can be appropriately emulated; therefore, an actual operation of the entire mini-plant for characterization experiments is no longer necessary. Full article

(This article belongs to the Section Industrial Crystallization)

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14 pages, 3246 KiB

Open AccessArticle

Scanning Tunneling Microscopy of Intermediate Transformation Structures in Electric Arc Surfacing Modified with Titanium Carbonitrides on Pipe Steel

by Kuznetsov Pavel, Galchenko Nina and Pochivalov Yury

Crystals 2023, 13(1), 146; https://doi.org/10.3390/cryst13010146 - 14 Jan 2023

Cited by 2 | Viewed by 1878

Abstract

In the present paper, the structure of electric arc coatings modified with nanodispersed titanium carbonitride additives on low-carbon pipe steel is studied using optical, scanning tunneling, and transmission electron microscopy. The obtained “substrate-modified surface” compositions are tested for fracture toughness, and the derived [...] Read more.

In the present paper, the structure of electric arc coatings modified with nanodispersed titanium carbonitride additives on low-carbon pipe steel is studied using optical, scanning tunneling, and transmission electron microscopy. The obtained “substrate-modified surface” compositions are tested for fracture toughness, and the derived test results are compared with the data for the compositions formed using commercial electrodes. It is found that the introduction of titanium carbonitride nanoparticles with the estimated content from 0.15 to 1 wt% refines the ferrite–pearlite structure. Scanning tunneling microscopy reveals acicular and lamellar structures in local regions of ferrite grains, which, by morphological features, are identified as lower bainite and acicular ferrite. It is concluded that the increase in fracture toughness of the “substrate-modified surface” composition is of a complex nature. First of all, this increase is associated with grain refinement, while the formation of intermediate transformation structures plays a secondary role. Full article

(This article belongs to the Special Issue Advances in Surface Modification of Metals and Alloys)

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26 pages, 7366 KiB

Open AccessReview

Crystal Engineering to Avoid Pairing Dipolar Moments: The Case of 5-Nitrouracil, a Highly Polarizable Molecule

by Manuela Ramos Silva and Pedro Pereira da Silva

Crystals 2023, 13(1), 145; https://doi.org/10.3390/cryst13010145 - 13 Jan 2023

Viewed by 1768

Abstract

5-nitrouracil is a polarizable molecule with a permanent electric dipole moment. Its molecular properties caught the attention of physicists working on nonlinear optics or optoelectronics, but the translation of the molecular assets to the crystalline solid has not been straightforward. This review compares [...] Read more.

5-nitrouracil is a polarizable molecule with a permanent electric dipole moment. Its molecular properties caught the attention of physicists working on nonlinear optics or optoelectronics, but the translation of the molecular assets to the crystalline solid has not been straightforward. This review compares all the known crystal structures incorporating the neutral or ionic 5-nitrouracil, or the two species concomitantly, discussing the effect of the packing in the optimization of the crystalline optical properties. Two new centrosymmetric 5-nitrouracilate salts are also reported for the first time, showing extensive hydrogen bonding between anions and cations. This review also gathers data from nonlinear optical measurements of non-centrosymmetric crystals and thermal stabilities of known polymorphs, showing that a neutral 5-nitrouracil molecule in acentric crystalline environment allows efficient blue-light generation. Full article

(This article belongs to the Section Crystal Engineering)

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19 pages, 21040 KiB

Open AccessReview

Organic Nonlinear Optical Crystals for Highly Efficient Terahertz-Wave Generation

by Ying Yang, Xinyuan Zhang, Zhanggui Hu and Yicheng Wu

Crystals 2023, 13(1), 144; https://doi.org/10.3390/cryst13010144 - 13 Jan 2023

Cited by 13 | Viewed by 3027

Abstract

Terahertz (THz) technology is an emerging field that is promising for future applications. Nonlinear optical (NLO) materials can effectively convert incident light into the THz frequency range using optics methods. Ionic-type organic π-conjugated NLO crystals containing electron donor-π-acceptor motifs have long attracted attention [...] Read more.

Terahertz (THz) technology is an emerging field that is promising for future applications. Nonlinear optical (NLO) materials can effectively convert incident light into the THz frequency range using optics methods. Ionic-type organic π-conjugated NLO crystals containing electron donor-π-acceptor motifs have long attracted attention for their possibility to achieve large nonlinear optical coefficients. In this paper, an overview of the recent progress in ionic-type organic NLO crystals for highly efficient THz wave generation is presented. The substitution design strategies of cations and anions, for increasing optical nonlinearities and reducing absorptions in different structure series, are summarized. In addition, the progress in crystal growth and their THz output performance are also discussed. Full article

(This article belongs to the Special Issue Nonlinear Crystals for Terahertz Generation)

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43 pages, 8424 KiB

Open AccessReview

The Structure, Property, and Ion Irradiation Effects of Pyrochlores: A Comprehensive Review

by Yuhao Wang, Chong Jing, Zhao-Ying Ding, Yun-Zhuo Zhang, Tao Wei, Jia-Hu Ouyang, Zhan-Guo Liu, Yu-Jin Wang and Ya-Ming Wang

Crystals 2023, 13(1), 143; https://doi.org/10.3390/cryst13010143 - 13 Jan 2023

Cited by 10 | Viewed by 4075

Abstract

Since the beginning of the use of nuclear energy, humans have been faced with the problem of radionuclide disposal. At present, a large amount of waste is stored in pools or dry tanks at reactor sites. With the development of the nuclear power [...] Read more.

Since the beginning of the use of nuclear energy, humans have been faced with the problem of radionuclide disposal. At present, a large amount of waste is stored in pools or dry tanks at reactor sites. With the development of the nuclear power generation industry worldwide, the high storage cost (including building, maintaining, and operating storage pools) is overwhelming and serious, and urgent radionuclide disposal problems have become increasingly difficult. Safe and economical strategies are urgently needed for long-term storage and disposal of nuclear waste, which has become among the core issues in the utilization of nuclear energy. Pyrochlore ceramics are able to immobilize a variety of radionuclides and have excellent irradiation stability, so they have received extensive attention as hosts of radionuclides waste. This review summarizes the structure, composition, synthesis process, properties, and irradiation stability of pyrochlore ceramics, focusing on the ion irradiation effect of pyrochlore. In general, the cation radii ratio r_A/r_B is a key parameter related to various properties of pyrochlores. Zirconate pyrochlore is more easily transformed from pyrochlore to defective fluorite, and leads to better irradiation resistance. Full article

(This article belongs to the Special Issue Microstructure Evolution, Property and Characterization of Crystalline Materials after Ion Irradiation)

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19 pages, 5320 KiB

Open AccessArticle

Lyotropic Liquid Crystal System for Drug Delivery of Astaxanthin: Physical Characterization and Enhanced Antioxidant Potential

by Sapna Kumari, Anju Goyal, Madhukar Garg, Angela Antonescu and Rakesh K. Sindhu

Crystals 2023, 13(1), 142; https://doi.org/10.3390/cryst13010142 - 13 Jan 2023

Cited by 8 | Viewed by 2690

Abstract

Astaxanthin is a xanthophyll carotenoid, well known for its potent anti-inflammatory and antioxidant properties, owing to its unsaturated molecular structure. Aquatic plants and animals contain the hydrophobic carotenoid astaxanthin, which is thought to possess a number of advantageous biological traits. However, due to [...] Read more.

Astaxanthin is a xanthophyll carotenoid, well known for its potent anti-inflammatory and antioxidant properties, owing to its unsaturated molecular structure. Aquatic plants and animals contain the hydrophobic carotenoid astaxanthin, which is thought to possess a number of advantageous biological traits. However, due to its weak bioavailability and low water solubility, its use as a nutraceutical in food is currently restricted. Cubosomal encapsulation has been considered an effective alternative for improving the bioavailability and solubility of hydrophobic bioactives. The current paper aimed to conquer these issues by encapsulating astaxanthin in lyotropic liquid crystal nano-formulations prepared via the fabrication method. The physicochemical properties of astaxanthin-loaded cubosomes (AST-LC) have also been analyzed, in order to know the morphology of the prepared formulations and their bioavailability in the biological system. The formulation has been tested for particle size, thermal behavior, zeta potential, crystallinity, encapsulation efficiency, and drug-polymer interactions. The observed experimental results showed the particle size and zeta potential of astaxanthin-loaded cubosomes (AST-LC) as 199 ± 0.23 nm −27.4 ± 4.67 mV, with a small polydispersity index (0.283 ± 1.01). The cubic structure and nano-range size of the ideal formulation were verified by a field emission scanning electron microscope (FESEM) and (HRTEM) high-resolution transmission electron microscopic examination. The formulation exhibits a higher encapsulation efficiency with good yield. Results from X-ray diffraction and diffraction scanning calorimetry demonstrated an amorphous state of astaxanthin incorporated into the formulation. Fourier transform infrared spectroscopy (FTIR) analysis of AST-LC showed the absence of astaxanthin main peaks, indicating its complete encapsulation inside the formulation. The drug–excipient interaction was carried out with diffraction scanning calorimetry DSC and FTIR, resulting in no interaction between them. These results offered important details about increasing astaxanthin bioavailability by incorporating it into cubosomes. Furthermore, the astaxanthin loaded into cubosomes has been evaluated for antioxidant potency, compared with astaxanthin extract using 2,2-diphenylpicrylhydrazylassay (DPPH assay). Full article

(This article belongs to the Special Issue Novel Nanomaterials for Catalytic and Biological Applications)

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8 pages, 1837 KiB

Open AccessCommunication

Ultrafast L Band Soliton Pulse Generation in Erbium-Doped Fiber Laser Based on Graphene Oxide Saturable Absorber

by Hazlihan Haris, Malathy Batumalay, Tan Sin Jin, Ahmad Razif Muhammad, Arni Munira Markom, Caroline Livan Anyi, Muhamad Hakim Izani, Mohd. Zulhakimi Ab. Razak, Megat Muhammad Ikhsan Megat Hasnan and Ismail Saad

Crystals 2023, 13(1), 141; https://doi.org/10.3390/cryst13010141 - 13 Jan 2023

Cited by 1 | Viewed by 2135

Abstract

We demonstrate a simple mode-locked Erbium-doped fiber laser (EDFL) based on self-synthesized saturable absorber (SA) by combining graphene oxide (GO) and polyethylene oxide (PEO) solutions to form a GO-PEO thin film. This thin film was incorporated into an Erbium-doped fiber laser (EDFL) with [...] Read more.

We demonstrate a simple mode-locked Erbium-doped fiber laser (EDFL) based on self-synthesized saturable absorber (SA) by combining graphene oxide (GO) and polyethylene oxide (PEO) solutions to form a GO-PEO thin film. This thin film was incorporated into an Erbium-doped fiber laser (EDFL) with a cavity length of 9 m. Our EDFL could operate at a 22 MHz repetition rate with a 0.8 ps pulse duration. The laser also showed stable soliton pulses under various laser pump power values. Our reported results show that GO-PEO SA is effective and proven as a cost-effective material for saturable absorbers for EDFLs. Full article

(This article belongs to the Special Issue Advances in Optical Fibers, Devices and Applications)

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13 pages, 5237 KiB

Open AccessArticle

Insight into the Structural, Mechanical and Optoelectronic Properties of Ternary Cubic Barium-Based BaMCl₃ (M = Ag, Cu) Chloroperovskites Compounds

by Mudasser Husain, Abd Ullah, Ali Algahtani, Vineet Tirth, Tawfiq Al-Mughanam, Abdulaziz H. Alghtani, Nourreddine Sfina, Khaoula Briki, Hind Albalawi, Mohammed A. Amin, Ahmed Azzouz-Rached and Nasir Rahman

Crystals 2023, 13(1), 140; https://doi.org/10.3390/cryst13010140 - 13 Jan 2023

Cited by 16 | Viewed by 2109

Abstract

Prediction of new materials is crucial for the advancement of technology. Here, in this research work, the first-principle computation has been conducted utilizing the WIEN2K package to probe the structural, electronic, mechanical, and optical properties of barium-based chloroperovskites BaMCl₃ (M = Ag, [...] Read more.

Prediction of new materials is crucial for the advancement of technology. Here, in this research work, the first-principle computation has been conducted utilizing the WIEN2K package to probe the structural, electronic, mechanical, and optical properties of barium-based chloroperovskites BaMCl₃ (M = Ag, Cu) compounds. The optimized lattice constants are calculated for both compounds which are 9.90 Bohr for BaAgCl₃ and 9.38 Bohr for BaCuCl₃. To obtain better and more precise results for the electronic band’s structure, TDOS and PDOS (total and partial density of states), and the TB-mBJ potential approximation are employed. The indirect band gap (R–Γ) is found for both compounds having values of 1.173 eV and 2.30 eV for BaCuCl₃ and BaAgCl₃, respectively, which depicts its semiconducting nature. The calculation of elastic properties is conducted with IRelast code. The Cauchy pressure, Bulk modulus, Young’s modulus, Shear modulus, anisotropic ratio, Kleinman parameters, and Poisson’s ratio are calculated from the obtained elastic constants. The computation of elastic parameters indicates that the interested chloroperovskites are anisotropic, mechanically stable, hard to scratch, and ductile. From 0 eV to 40 eV incident photon energy ranges, the various optical parameter such as refractive index, absorption coefficient, dielectric function, reflectivity, extinction coefficient, and optical conductivity are analyzed. These compounds absorb maximum light within 5 to 25 eV incident photon energy. Hence, these materials are good light absorbers, therefore, they can be used in optoelectronic devices for high-frequency applications. Full article

(This article belongs to the Special Issue Wide Bandgap Semiconductor Electronics and Optoelectronics)

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11 pages, 5359 KiB

Open AccessArticle

Very High Cycle Fatigue Damage of TC21 Titanium Alloy under High/Low Two-Step Stress Loading

by Baohua Nie, Shuai Liu, Yue Wu, Yu Song, Haiying Qi, Binqing Shi, Zihua Zhao and Dongchu Chen

Crystals 2023, 13(1), 139; https://doi.org/10.3390/cryst13010139 - 13 Jan 2023

Cited by 2 | Viewed by 1637

Abstract

Very high cycle fatigue (VHCF) tests were carried out under variable amplitude loading for TC21 titanium alloy. The first level of high amplitude loading was set as 950 MPa close to yield strength, and the second level of low amplitude loading was determined [...] Read more.

Very high cycle fatigue (VHCF) tests were carried out under variable amplitude loading for TC21 titanium alloy. The first level of high amplitude loading was set as 950 MPa close to yield strength, and the second level of low amplitude loading was determined between 435 MPa and 500 MPa where fatigue cracks initiated at the specimen subsurface under constant amplitude. The results indicate that the high/low stress block significantly reduced the cumulative fatigue life of low stress amplitude, and the fatigue crack initiation site changed from the specimen subsurface under constant loading to the specimen surface under stress block. Based on continuum damage mechanics, the fatigue damage model of two-step stress block was established to estimate the fatigue damage process. The prediction of cumulative fatigue life generally agreed with the experimental data. The cumulative fatigue damage of the stress block was related to the stress amplitude and the cycle ratio, which determined the stress fatigue damage and its interaction damage. The surface crack initiation in the stress block accelerated fatigue damage of low stress amplitude, reducing the cumulative life. Full article

(This article belongs to the Special Issue Advances in High Strength Steels)

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21 pages, 7575 KiB

Open AccessArticle

A New Non-linear Stilbazolium Derivative Crystal of 4-[2-(3 Methoxy-phenyl)-vinyl]-1-methyl-pyridinium⁺ Iodide⁻ (MMPI): Analysis of Its Structural, Surface, Optical and NLO Properties

by Nandhini Krishnan and Kalainathan Sivaperuman

Crystals 2023, 13(1), 138; https://doi.org/10.3390/cryst13010138 - 12 Jan 2023

Cited by 7 | Viewed by 2591

Abstract

New organic stilbazolium family of 4-[2-(3 methoxy-phenyl)-vinyl]-1-methyl-pyridinium⁺ iodide⁻ (MMPI) was successfully synthesized using the condensation reaction method. The recrystallization process was carried out to improve the purity of the synthesized material, and MMPI and grown into a single crystal by the [...] Read more.

New organic stilbazolium family of 4-[2-(3 methoxy-phenyl)-vinyl]-1-methyl-pyridinium⁺ iodide⁻ (MMPI) was successfully synthesized using the condensation reaction method. The recrystallization process was carried out to improve the purity of the synthesized material, and MMPI and grown into a single crystal by the solvent evaporation method. The solubility of the (MMPI) material was taken at different temperatures with a mixture of solvent Methanol: Acetonitrile (1:1). The grown MMPI crystal structure and cell parameters were solved via single crystal X-ray diffraction analysis. The structural formation of the title material was also confirmed by Nuclear Magnetic Resonance spectroscopic (NMR) studies. The experimental vibrational bands in the synthesized material have been assigned by Fourier Transform Infrared (FT-IR) spectrum analysis. From the optical analysis, the grown crystal’s lower cut-off wavelength, transmittance range, and optical band gap were calculated. Chemical etching analysis was carried out on the grown crystal surface (MMPI) to study the surface property of the grown MMPI crystal. Along with etching, atomic force microscope (AFM) and scanning electron microscope (SEM) were also used to analyses the grown MMPI crystal surface. Hirshfeld surface analysis was used to analyses the intermolecular interactions. HOMO and LUMO energies were calculated theoretically using the Gaussian View 6 programmer. The chemical activity was evaluated via the molecular electrostatic potential using the density functional theory (DFT) method. The third-order nonlinear optical parameters of the title crystal were evaluated at He-Ne laser (632.8 nm) source with the single beam Z-scan technique. In addition, it shows significant reverse saturable absorption and self-defocusing. Full article

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17 pages, 7775 KiB

Open AccessArticle

Experiments and Crystal Plasticity Finite Element Simulations of Texture Development during Cold Rolling in a Ti-15V-3Cr-3Sn-3Al Alloy

by Diksha Mahadule, Murat Demiral, Hasan Mulki and Rajesh K. Khatirkar

Crystals 2023, 13(1), 137; https://doi.org/10.3390/cryst13010137 - 12 Jan 2023

Cited by 6 | Viewed by 2516

Abstract

The effect of deformation on the evolution of crystallographic texture in a Ti-15V-3Cr-3Sn-3Al (Ti-15333) alloy after unidirectional cold rolling was studied experimentally and numerically in the present investigation. An optical microscope (OM) and scanning electron microscope (SEM) were used to study the microstructures, [...] Read more.

The effect of deformation on the evolution of crystallographic texture in a Ti-15V-3Cr-3Sn-3Al (Ti-15333) alloy after unidirectional cold rolling was studied experimentally and numerically in the present investigation. An optical microscope (OM) and scanning electron microscope (SEM) were used to study the microstructures, while the crystallographic texture after cold rolling was studied with X-ray diffraction. The rolling process (deformation) was simulated with PRISMS-plasticity, open-source crystal plasticity software. Micro-indentations were performed on the initial solution-annealed sample with an equiaxed grain structure. The experimentally obtained load–displacement curve for a particular grain (orientation-φ₁, Φ, φ₂ = 325.2°, 18.0°, 66.2° (Bunge notation)) was compared with the crystal plasticity finite element method (FEM)-simulated load–displacement curve to obtain the calibration parameters. The obtained parameters, along with the experimental stress–strain curve, were used to recalibrate the PRISMS-plasticity software for the rolling simulations of the Ti-15333 alloy. It was observed that the γ-(normal direction, ND//<111>) and α-(rolling direction, RD//<110>) fibers strengthened with cold rolling, experimentally as well as numerically. The simulated orientation distribution functions (ODFs) matched reasonably well with those obtained from the experiments. The average values of von Mises stress and von Mises strain increased with an increase in deformation. Full article

(This article belongs to the Special Issue Feature Papers in Crystalline Metals and Alloys in 2022–2023)

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8 pages, 1296 KiB

Open AccessBrief Report

Real-Time In-Situ Investigation of the Neutron Irradiation Resistance Ability of Nd³⁺-Doped Gd₃Sc₂Al₃O₁₂ Laser Crystal

by Yuxi Gao, Wenpeng Liu, Shoujun Ding, Yuanzhi Chen and Qingli Zhang

Crystals 2023, 13(1), 136; https://doi.org/10.3390/cryst13010136 - 12 Jan 2023

Viewed by 1537

Abstract

In optical crystals, photodarkening will occur after they were irradiated with high-energy particles, and such induced optical loss generally results in significant performance degradation whether they are used as passive or active optical elements. In the present study, the effects of neutron irradiation [...] Read more.

In optical crystals, photodarkening will occur after they were irradiated with high-energy particles, and such induced optical loss generally results in significant performance degradation whether they are used as passive or active optical elements. In the present study, the effects of neutron irradiation on the optical response of the Nd³⁺-doped Gd₃Sc₂Al₃O₁₂ (Nd:GSAG) single crystal has been revealed in real-time and in-situ. Transient and permanent transmittance reduction in the crystal induced by neutron radiation has been observed and the reduction mechanisms have been analyzed. The XRD characterization method demonstrated that the crystal structure remained constant both before and after neutron irradiation. Importantly, the X-ray photoelectron peak of the O 1s core level shifts to high binding energy, indicating that oxygen vacancies were produced in the crystal after irradiation with neutrons. Thus, the permanent reduction in the transmittance of the crystal after irradiation with neutrons can be attributed to the generation of oxygen vacancies in the crystal. To the best of our knowledge, it is the first time the damage types in rare earth oxide laser crystals caused by neutron irradiation were revealed. Full article

(This article belongs to the Special Issue Advances in Optoelectric Functional Crystalline Materials)

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17 pages, 6244 KiB

Open AccessArticle

Enhancing the Structural, Optical, Thermal, and Electrical Properties of PVA Filled with Mixed Nanoparticles (TiO₂/Cu)

by Ahmed N. Al-Hakimi, G. M. Asnag, Fahad Alminderej, Ibrahim A. Alhagri, Sadeq M. Al-Hazmy and Talal F. Qahtan

Crystals 2023, 13(1), 135; https://doi.org/10.3390/cryst13010135 - 12 Jan 2023

Cited by 32 | Viewed by 2737

Abstract

In this work, new samples of PVA-TiO₂/Cu nanocomposites were prepared via the casting method. The prepared samples were examined using different analytical methods. An XRD analysis showed the semi-crystalline nature of the PVA polymer, as well as showing a decrease in [...] Read more.

In this work, new samples of PVA-TiO₂/Cu nanocomposites were prepared via the casting method. The prepared samples were examined using different analytical methods. An XRD analysis showed the semi-crystalline nature of the PVA polymer, as well as showing a decrease in the degree of the crystallinity of the PVA structure as a result of the addition of the mixed nanoparticles. TEM images indicate the spherical shape of the Cu NPs, with a size ranging from 2 to 22 nm, and the rectangular shape of the TiO₂ NPs, with a size ranging from 5 to 25 nm. It was evident via FTIR measurements that there were interactions between the functional groups of the PVA and the TiO₂/Cu NPs. The optical properties of the PVA nanocomposites were improved with an increase in the content of the TiO₂/Cu nanoparticles, as shown via a UV/Vis analysis. DSC curves showed an improvement in the thermal stability of the PVA-TiO₂/Cu nanocomposites after the embedding of the TiO₂/Cu nanoparticles. It was evident using impedance spectroscopy that the AC conductivity was improved by adding the TiO₂ and Cu nanoparticles to the polymeric matrix. The maximum AC conductivity was found at 1.60 wt.% of TiO₂/Cu nanoparticles in the PVA polymer, and this was 13.80 × 10⁻⁶ S/cm at room temperature. Relaxation occurred as a result of the charge carrier hopping between the localized state and the correlated barriers hopping model, describing the dominant mechanism, as presented in an electrical modulus analysis. These results indicate that the PVA-TiO₂/Cu nanocomposite samples can be used in energy storage capacitor applications and in the alternative separator-rechargeable lithium-ion battery industry. Full article

(This article belongs to the Section Materials for Energy Applications)

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18 pages, 23590 KiB

Open AccessArticle

Effect of Grain Sizes on Electrically Assisted Micro—Filling of SUS304 Stainless Steel: Experiment and Simulation

by Mingliang Men, Rui Zhao, Yizhe Liu, Min Wan and Bao Meng

Crystals 2023, 13(1), 134; https://doi.org/10.3390/cryst13010134 - 12 Jan 2023

Cited by 1 | Viewed by 1885

Abstract

The filling quality of micro-feature structures has a significant impact on the forming quality of micro-channels. The electrical-assisted forming technology can effectively improve the formability of difficult-to-deform materials. In this research, the electrically driven micro-compression constitutive model of SUS304 stainless steels was established [...] Read more.

The filling quality of micro-feature structures has a significant impact on the forming quality of micro-channels. The electrical-assisted forming technology can effectively improve the formability of difficult-to-deform materials. In this research, the electrically driven micro-compression constitutive model of SUS304 stainless steels was established to assign grain boundary and grain interior with different material properties. An electrical–thermal–mechanical coupling model was constructed to simulate the filling process considering the effect of grain boundary and grain size. Compared to the experimental results, the simulation indicated a good agreement in microstructure characteristics and higher filling height for the fine-grained material. The increase in grain boundary density makes the resistivity of the fine grain material larger, causing the current destiny and temperature of the specimen to increase with the decrease in grain size. An ellipsoidal gradient temperature distribution is observed due to the uneven current density. Because of the high geometric dislocation density near the grain boundary, a significant dislocation pile-up causes stress to concentrate. It is observed that the deformation coordination is enhanced between the grain boundary and grain core with the decrease in grain size, thus improving the material formability and forming quality. Full article

(This article belongs to the Special Issue Dislocation Mechanics of Crystal/Polycrystal Mechanical Strength Properties)

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19 pages, 3789 KiB

Open AccessArticle

Microwave-Assisted Synthesis of rGO-ZnO/CuO Nanocomposites for Photocatalytic Degradation of Organic Pollutants

by Aklilu Guale Bekru, Lemma Teshome Tufa, Osman Ahmed Zelekew, Juyong Gwak, Jaebeom Lee and Fedlu Kedir Sabir

Crystals 2023, 13(1), 133; https://doi.org/10.3390/cryst13010133 - 12 Jan 2023

Cited by 12 | Viewed by 3842

Abstract

Nanomaterial-based catalytic conversion of hazardous organic pollutants into benign substances is one of the green methods employed for wastewater treatment. This study demonstrates the fabrication of (rGO-ZnO)/CuO nanocomposites (NCs) via a microwave (MW)-assisted method for (photo)catalytic application. The crystal structure, optical, morphological, and [...] Read more.

Nanomaterial-based catalytic conversion of hazardous organic pollutants into benign substances is one of the green methods employed for wastewater treatment. This study demonstrates the fabrication of (rGO-ZnO)/CuO nanocomposites (NCs) via a microwave (MW)-assisted method for (photo)catalytic application. The crystal structure, optical, morphological, and electrochemical characteristics were examined using X-ray diffraction (XRD), spectroscopic, microscopic, and electrochemical techniques. The analysis indicated that rod-like (rGO-ZnO)/CuO NCs having a nanoscale diameter with enhanced light absorption and well-matched band positions between rGO-ZnO and CuO were formed. Furthermore, the catalytic reduction of 4-nitrophenol (4-NP) and photocatalytic degradation of methylene blue (MB) tests showed remarkable results with rate constants of 0.468 min⁻¹ for 4-NP reduction within 8 min and 0.02213 min⁻¹ for MB degradation within 105 min. Thus, the artful decoration of ZnO nanorods (NRs) with CuO into the (rGO-ZnO)/CuO NCs interface is an effective strategy for fabricating highly efficient photocatalysts. Full article

(This article belongs to the Special Issue Synthesis, Characterization and Application of Novel Nanoparticles)

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11 pages, 2083 KiB

Open AccessArticle

Synergistic Occlusion of Doxorubicin and Hydrogels in CaCO₃ Composites for Controlled Drug Release

by Ya-Xin Li and Yuan Jiang

Crystals 2023, 13(1), 132; https://doi.org/10.3390/cryst13010132 - 11 Jan 2023

Cited by 1 | Viewed by 1971

Abstract

Extensive exploration is required to deploy mineralization as a tool to develop low-cost yet efficient sustained drug release systems. Unlike previous studies which directly incorporated drug components in mineralized products, we propose an emerging approach to synthesizing drug-loaded CaCO₃ composites, relying on [...] Read more.

Extensive exploration is required to deploy mineralization as a tool to develop low-cost yet efficient sustained drug release systems. Unlike previous studies which directly incorporated drug components in mineralized products, we propose an emerging approach to synthesizing drug-loaded CaCO₃ composites, relying on the synergistic occlusion of the molecular solutions comprising both the alginate hydrogel matrices and the associated drug (doxorubicin) in the course of mineralization. Independent tools including a scanning electron microscope and adsorption isotherm were employed to characterize the lyophilized composites, which led to the conclusion that the anticancer drug doxorubicin (DOX) was uniformly dispersed in the hydrogel matrices as a molecular solution. The occlusion strategy led to CaCO₃-based composites with high loads and sustained and pH-responsive release of DOX. Considering many drug molecules can form molecular solutions with polymeric components, we find that the synergistic occlusion can become a general approach to designing smart drug delivery systems. Full article

(This article belongs to the Section Mineralogical Crystallography and Biomineralization)

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18 pages, 4726 KiB

Open AccessReview

A Comprehensive Review of Large-Strain-Extrusion Machining Process for Production of Fine-Grained Materials

by Muralimohan Gurusamy and Balkrishna C. Rao

Crystals 2023, 13(1), 131; https://doi.org/10.3390/cryst13010131 - 11 Jan 2023

Viewed by 2091

Abstract

Bulk nanostructured metals and alloys are finding increasing structural applications due to their superior mechanical properties. The methods that rely on the severe plastic deformation technique for effecting microstructural refinement through imposing large strains are utilized mostly to produce nanostructured materials. The machining [...] Read more.

Bulk nanostructured metals and alloys are finding increasing structural applications due to their superior mechanical properties. The methods that rely on the severe plastic deformation technique for effecting microstructural refinement through imposing large strains are utilized mostly to produce nanostructured materials. The machining process has been demonstrated as a simple process for severe plastic deformation by imposing large strains through a single pass of the cutting tool where strains in a range of 1–15 can be imposed for a variety of materials by varying the cutting conditions and tool geometry. However, the geometry of the resulting chip subjected to severe plastic deformation during the machining process is not under control and, hence, a variant of the machining process, called the large-strain-extrusion machining process, has been proposed and utilized extensively for producing bulk nanostructured materials. Large-strain-extrusion machining possesses simultaneous control over microstructure refinement, through managing the strain during large-strain machining, and the shape and dimension of the resulting chip by the extrusion process. This study provides a comprehensive review of the large-strain-extrusion machining process by presenting the findings related to the utilization of this process for the production of fine-grained foils for various metals and alloys. Further research efforts related to finite-element modelling of large-strain-extrusion machining and their usefulness in designing the experimental setup and process conditions are also discussed. Full article

(This article belongs to the Special Issue Dislocation Mechanics of Crystal/Polycrystal Mechanical Strength Properties)

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18 pages, 8927 KiB

Open AccessArticle

Isotropic TFT Characteristics in the {100}-Oriented Grain-Boundary-Free Laser-Crystallized Si Thin Films

by Nobuo Sasaki, Satoshi Takayama, Rikuto Sasai and Yukiharu Uraoka

Crystals 2023, 13(1), 130; https://doi.org/10.3390/cryst13010130 - 11 Jan 2023

Cited by 5 | Viewed by 1856

Abstract

Isotropic TFT characteristics are realized in the {100}-oriented grain-boundary-free 60 nm thick Si film obtained by the continuous-wave laser lateral crystallization, where the grain- and sub-boundaries are defined as the crystallographic boundaries having misfit angles of θ > 15° and θ < 15°, [...] Read more.

Isotropic TFT characteristics are realized in the {100}-oriented grain-boundary-free 60 nm thick Si film obtained by the continuous-wave laser lateral crystallization, where the grain- and sub-boundaries are defined as the crystallographic boundaries having misfit angles of θ > 15° and θ < 15°, respectively. Sub-boundaries are observed in the film parallel to the scan directions; the misfit angles were 5–10° and the sub-boundary density was 0.02956 μm⁻¹. Sub-grains, joined by the sub-boundaries, have widths of 8 ~ 69 μm. The cumulative distributions of mobility, threshold voltage, and subthreshold swing agree well between the parallel and perpendicular TFTs in the film, where parallel or perpendicular means the source-to-drain directions to the laser scan direction. The maximum mobilities of the parallel and perpendicular TFTs are 695 and 663 cm²/Vs, respectively. The trap-state density N_T in the sub-boundaries estimated from the product of the bond efficiency η and the dangling bond density decreases by two decades from those of the grain boundaries. A new carrier transport model of the current flow across the sub-boundary is proposed instead of the thermionic emission model for the grain boundaries. Full article

(This article belongs to the Section Industrial Crystallization)

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11 pages, 5644 KiB

Open AccessArticle

Effects of Nitrogen Content and Strain Rate on the Tensile Behavior of High-Nitrogen and Nickel-Free Austenitic Stainless Steel

by Feng Shi, Xinyue Zhang, Tianzeng Li, Xianjun Guan, Xiaowu Li and Chunming Liu

Crystals 2023, 13(1), 129; https://doi.org/10.3390/cryst13010129 - 11 Jan 2023

Cited by 5 | Viewed by 1783

Abstract

The uniaxial tensile behaviors of Fe-19Cr-16Mn-2Mo-0.49N and Fe-18Cr-16Mn-2Mo-0.85N high-nitrogen and nickel-free austenitic stainless steels at two strain rates of 10⁻² s⁻¹ and 10⁻⁴ s⁻¹ were comparatively investigated. The related deformation microstructure was characterized and fracture mechanism was analyzed. The [...] Read more.

The uniaxial tensile behaviors of Fe-19Cr-16Mn-2Mo-0.49N and Fe-18Cr-16Mn-2Mo-0.85N high-nitrogen and nickel-free austenitic stainless steels at two strain rates of 10⁻² s⁻¹ and 10⁻⁴ s⁻¹ were comparatively investigated. The related deformation microstructure was characterized and fracture mechanism was analyzed. The results show that the nitrogen content and strain rate both have significant effects on the tensile properties of the tested steels. As the strain rate is the same, the tested steel containing a higher nitrogen content has higher R_m and R_p_0.2. However, R_m is higher at a lower strain rate and R_p_0.2 is higher at a higher strain rate in the case of the same nitrogen content. The tested steel with a lower nitrogen content (0.49 wt.%N) tensioned at a lower strain rate of 10⁻⁴ s⁻¹ obtains the highest elongation, while the tested steel with a higher nitrogen content (0.85 wt.%N) tensioned at a higher strain rate of 10⁻² s⁻¹ has the lowest elongation. The tensile plastic deformation is mainly governed by slip and twinning, affected jointly by stacking fault energy and short-range order. Dislocation slip featured by planar slip bands and twin-like bands is the main deformation structure in the tested steel containing a higher nitrogen content (0.85 wt.%N) tensioned at a lower strain rate of 10⁻⁴ s⁻¹, whereas twinning deformation becomes more prominent with decreasing nitrogen content and increasing strain rate. Full article

(This article belongs to the Special Issue Advances in High Strength Steels)

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17 pages, 2272 KiB

Open AccessArticle

Sensing and Detection Capabilities of One-Dimensional Defective Photonic Crystal Suitable for Malaria Infection Diagnosis from Preliminary to Advanced Stage: Theoretical Study

by Sujit Kumar Saini and Suneet Kumar Awasthi

Crystals 2023, 13(1), 128; https://doi.org/10.3390/cryst13010128 - 11 Jan 2023

Cited by 21 | Viewed by 2638

Abstract

In the present research work we have examined the biosensing capabilities of one-dimensional photonic crystals with defects for the detection and sensing of malaria infection in humans by investigating blood samples containing red blood cells. This theoretical scheme utilizes a transfer matrix formulation [...] Read more.

In the present research work we have examined the biosensing capabilities of one-dimensional photonic crystals with defects for the detection and sensing of malaria infection in humans by investigating blood samples containing red blood cells. This theoretical scheme utilizes a transfer matrix formulation in addition to MATLAB software under normal incidence conditions. The purpose of considering normal incidence is to rule out the difficulties associated with oblique incidence. We have examined the performance of various structures of cavity layer thicknesses 1000 nm, 2200 nm, 3000 nm and 5000 nm. The comparison between the performances of various structures of different cavity thickness helps us to select the structure of particular cavity thicknesses giving optimum biosensing performance. Thus, the proper selection of cavity thickness is one of the most necessary requirements because it also decides how much volume of the blood sample has to be poured into the cavity to produce results of high accuracy. Moreover, the sensing and detection capabilities of the proposed design have been evaluated by examining the sensitivity, figure of merit and quality factor values of the design, corresponding to optimum cavity thickness. Full article

(This article belongs to the Special Issue 1D and 2D Nanomaterials for Sensor Applications)

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11 pages, 2237 KiB

Open AccessArticle

Investigation into the MOCVD Growth and Optical Properties of InGaN/GaN Quantum Wells by Modulating NH₃ Flux

by Zhenyu Chen, Feng Liang, Degang Zhao, Jing Yang, Ping Chen and Desheng Jiang

Crystals 2023, 13(1), 127; https://doi.org/10.3390/cryst13010127 - 10 Jan 2023

Cited by 3 | Viewed by 2268

Abstract

In this study, the surface morphology and luminescence characteristics of InGaN/GaN multiple quantum wells were studied by applying different flow rates of ammonia during MOCVD growth, and the best growth conditions of InGaN layers for green laser diodes were explored. Different emission peak [...] Read more.

In this study, the surface morphology and luminescence characteristics of InGaN/GaN multiple quantum wells were studied by applying different flow rates of ammonia during MOCVD growth, and the best growth conditions of InGaN layers for green laser diodes were explored. Different emission peak characteristics were observed in temperature-dependent photoluminescence (TDPL) examination, which showed significant structural changes in InGaN layers and in the appearance of composite structures of InGaN/GaN quantum wells and quantum-dot-like centers. It was shown that these changes are caused by several effects induced by ammonia, including both the promotion of indium corporation and corrosion from hydrogen caused by the decomposition of ammonia, as well as the decrease in the surface energy of InGaN dot-like centers. We carried out detailed research to determine ammonia’s mechanism of action during InGaN layer growth. Full article

(This article belongs to the Special Issue III-Nitride Materials: Properties, Growth, and Applications)

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11 pages, 736 KiB

Open AccessArticle

Structural, Mechanical, and Piezoelectric Properties of Janus Bidimensional Monolayers

by Abdulrahman Mallah, Mourad Debbichi, Mohamed Houcine Dhaou and Bilel Bellakhdhar

Crystals 2023, 13(1), 126; https://doi.org/10.3390/cryst13010126 - 10 Jan 2023

Cited by 5 | Viewed by 2081

Abstract

In the present work, the noncentrosymmetric 2D ternary Janus monolayers Al

_{2}

XX’(X/X’ = S, Se, Te and O), Si

_{2}

XX’(X/X’ = P, As, Sb and Bi), and A

_{2}

PAs(A = Ge, Sn and Pb) have been studied based on first-principles [...] Read more.

In the present work, the noncentrosymmetric 2D ternary Janus monolayers Al

_{2}

XX’(X/X’ = S, Se, Te and O), Si

_{2}

XX’(X/X’ = P, As, Sb and Bi), and A

_{2}

PAs(A = Ge, Sn and Pb) have been studied based on first-principles calculations. We find that all the monolayers exhibit in-plane d

_{12}

, and out-of-plane d

_{13}

piezoelectric coefficients due to the lack of reflection symmetry with respect to the central A atoms. Moreover, our calculations show that Al

_{2}

OX(T = S, Se, Te) chalcogenide monolayers have higher absolute in-plane piezoelectric coefficients. However, the highest out-of-plane values are achieved in the Si

_{2}

PBi monolayer, larger than those of some advanced piezoelectric materials, making them very promising transducer materials for lightweight and high-performance piezoelectric nanodevices. Full article

(This article belongs to the Special Issue Magnetic, Dielectric, Electrical, Optical and Thermal Properties of Crystalline Materials)

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17 pages, 7474 KiB

Open AccessArticle

Low-Cost Graphene-Based Composite Electrodes for Electrochemical Oxidation of Phenolic Dyes

by Marija Ječmenica Dučić, Aleksandar Krstić, Nikola Zdolšek, Danka Aćimović, Branislava Savić, Tanja Brdarić and Dragana Vasić Anićijević

Crystals 2023, 13(1), 125; https://doi.org/10.3390/cryst13010125 - 10 Jan 2023

Cited by 3 | Viewed by 2400

Abstract

Electrochemical removal of organic pollutants represents an attractive methodology in water depollution. The key challenges for researchers comprise finding simple, affordable electrode materials with satisfactory efficiency in all ranges of pollutant concentration. Electrochemical oxidation of a mixture of phenol-based dyes: bromocresol green (BCG), [...] Read more.

Electrochemical removal of organic pollutants represents an attractive methodology in water depollution. The key challenges for researchers comprise finding simple, affordable electrode materials with satisfactory efficiency in all ranges of pollutant concentration. Electrochemical oxidation of a mixture of phenol-based dyes: bromocresol green (BCG), cresol red (CR), and thymol blue (TB), in sulphate medium, at total concentration not exceeding 15 ppm, has been performed using simply prepared, low-cost composite electrodes, based on graphene nanoplatelets (GNP) and metallic oxides (TiO₂ and SnO₂) loaded on stainless steel substrate: GNP@SS, SnO₂/GNP@SS, and TiO₂/GNP@SS. Electrodes were characterised by XRD, FTIR, and electrochemical techniques. The degradation kinetics of initial dyes was tracked with UPLC and GC-MS chromatography for 6 h, at a current density of 10 mA/cm². GC-MS analysis of the degradation products revealed oxidised aromatic compounds as the main products, while TOC analysis confirmed a total mineralisation extent in the range of 30–35%. The proposed degradation mechanism involves the attack of OH-radical, as the main oxidising agent, to the hydroxyl oxygens of dye phenolic rings. Obtained results provide useful information for the further development of affordable laboratory-scale and industrial systems for the complete removal of phenol-based compounds. Full article

(This article belongs to the Special Issue Macromolecular Crystalline Materials (MCMs) for Clean Energy and Green Environment)

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