Journal Description
Crystals
Crystals
is an international, peer-reviewed, open access journal on Crystallography published monthly online by MDPI. The Professional Committee of Key Materials and Technology for Electronic Components (PC-KMTEC) is affiliated with Crystals and its members receive discounts on the article processing charges.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within Scopus, SCIE (Web of Science), Inspec, CAPlus / SciFinder, and other databases.
- Journal Rank: JCR - Q2 (Crystallography) / CiteScore - Q2 (Condensed Matter Physics)
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 10.6 days after submission; acceptance to publication is undertaken in 2.7 days (median values for papers published in this journal in the second half of 2023).
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
Impact Factor:
2.7 (2022);
5-Year Impact Factor:
2.6 (2022)
Latest Articles
Combined Effect of Particle Reinforcement and T6 Heat Treatment on the Compressive Deformation Behavior of an A357 Aluminum Alloy at Room Temperature and at 350 °C
Crystals 2024, 14(4), 317; https://doi.org/10.3390/cryst14040317 - 28 Mar 2024
Abstract
Solid state sintering of cast aluminum powders by resistance heating sintering (RHS), also known as spark plasma sintering or field-assisted sintering technique, creates a very fine microstructure in the bulk material. This leads to high performance material properties with an improved strength and
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Solid state sintering of cast aluminum powders by resistance heating sintering (RHS), also known as spark plasma sintering or field-assisted sintering technique, creates a very fine microstructure in the bulk material. This leads to high performance material properties with an improved strength and ductility compared to conventional production routes of the same alloys. In this study, the mechanical behavior of an RHS-sintered age-hardenable A357 (AlSi7Mg0.6) cast alloy and a SiCp/A357 aluminum matrix composite (AMC) was investigated. Aiming for high strength and good wear behavior in tribological applications, the AMC was reinforced with a high particle content (35 vol.%) of a coarse particle fraction (d50 = 21 µm). Afterwards, separated and combined effects of particle reinforcement and heat treatment were studied under compressive load both at room temperature and at 350 °C. At room temperature compression, the strengthening effect of precipitation hardening was about twice as high as that for the particle reinforcement, despite the high particle content. At elevated temperatures, the compressive deformation behavior was characterized by simultaneously occurring temperature-activated recovery, recrystallisation and precipitation processes. The occurrence and interaction of these processes was significantly affected by the initial material condition. Moreover, a rearrangement of the SiC reinforcement particles was detected after hot deformation. This rearrangement lead to a homogenized dispersion of the reinforcement phase without considerable particle fragmentation, which offers the potential for secondary thermo-mechanical processing of highly reinforced AMCs.
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(This article belongs to the Special Issue Advances in Metal Matrix Composites: Structure, Properties and Applications)
Open AccessArticle
A Closed-Form Solution to the Mechanism of Interface Crack Formation with One Contact Area in Decagonal Quasicrystal Bi-Materials
by
Zhiguo Zhang, Baowen Zhang, Xing Li and Shenghu Ding
Crystals 2024, 14(4), 316; https://doi.org/10.3390/cryst14040316 - 28 Mar 2024
Abstract
Cracks and crack-like defects in engineering structures have greatly reduced the structural strength. An interface crack with one contact area in a combined tension–shear field of decagonal quasicrystal bi-material is investigated. Based on the deformation compatibility equation and displacement potential function, the complex
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Cracks and crack-like defects in engineering structures have greatly reduced the structural strength. An interface crack with one contact area in a combined tension–shear field of decagonal quasicrystal bi-material is investigated. Based on the deformation compatibility equation and displacement potential function, the complex representation of stress and displacement is given. Using the mixed boundary conditions, the closed-form expressions for the stresses and the displacement jumps in the phonon field and phason field on the material interface are obtained. The results show that the stress intensity factor at the crack tip is zero for the phason field. The variation in the stress intensity factor and the length of the contact zone in the phonon field is given, and the result is consistent with the properties of the crystal. The design of safe engineering structures and the formulation of reasonable quality acceptance standards may benefit from the theoretical research carried out here.
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(This article belongs to the Special Issue Structures, Properties and Applications of Quasicrystals)
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Open AccessArticle
Cavitation Erosion of the Austenitic Manganese Layers Deposited by Pulsed Current Electric Arc Welding on Duplex Stainless Steel Substrates
by
Ion Mitelea, Daniel Mutașcu, Ion-Dragoș Uțu, Corneliu Marius Crăciunescu and Ilare Bordeașu
Crystals 2024, 14(4), 315; https://doi.org/10.3390/cryst14040315 - 28 Mar 2024
Abstract
Fe-Mn-Cr-Ni alloys like Citomangan, delivered in the form of powders, tubular wires, and coated electrodes, are intended for welding deposition operations to create wear-resistant layers. Their main characteristic is their high capacity for surface mechanical work-hardening under high shock loads, along with high
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Fe-Mn-Cr-Ni alloys like Citomangan, delivered in the form of powders, tubular wires, and coated electrodes, are intended for welding deposition operations to create wear-resistant layers. Their main characteristic is their high capacity for surface mechanical work-hardening under high shock loads, along with high toughness and wear resistance. In order to increase the resistance to cavitation erosion, hardfacing of Duplex stainless steel X2CrNiMoN22-5-3 with Citomangan alloy was performed using a new welding technique, namely one that uses a universal TIG source adapted for manual welding with a coated electrode in pulsed current. Cavitation tests were conducted in accordance with the requirements of ASTM G32—2016 standard. Comparing the characteristic cavitation erosion parameters of the manganese austenitic layer, deposited by this new welding technique, with those of the reference steel, highlights an 8–11 times increase in its resistance to cavitation erosion. Metallographic investigations by optical microscopy and scanning electron microscopy (SEM), as well as hardness measurements, were carried out to understand the cavitation phenomena.
Full article
(This article belongs to the Special Issue Advanced Crystalline Materials, Mechanical Properties and Innovative Production Systems (2nd Edition))
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Open AccessArticle
Mechanical Properties of Small Quasi-Square Graphene Nanoflakes
by
Andrés Serna-Gutiérrez and Nicolás A. Cordero
Crystals 2024, 14(4), 314; https://doi.org/10.3390/cryst14040314 - 28 Mar 2024
Abstract
The rise of straintronics—the possibility of fine-tuning the electronic properties of nanosystems by applying strain to them—has enhanced the interest in characterizing the mechanical properties of these systems when they are subjected to tensile (or compressive), shear and torsion strains. Four parameters are
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The rise of straintronics—the possibility of fine-tuning the electronic properties of nanosystems by applying strain to them—has enhanced the interest in characterizing the mechanical properties of these systems when they are subjected to tensile (or compressive), shear and torsion strains. Four parameters are customarily used to describe the mechanical behavior of a macroscopic solid within the elastic regime: Young’s and shear moduli, the torsion constant and Poisson’s ratio. There are some relations among these quantities valid for elastic continuous isotropic systems that are being used for 2D nanocrystals without taking into account the non-continuous anisotropic nature of these systems. We present in this work computational results on the mechanical properties of six small quasi-square (aspect ratio between 0.9 and 1.1) graphene nanocrystals using the PM7 semiempirical method. We use the results obtained to test the validity of two relations derived for macroscopic homogeneous isotropic systems and sometimes applied to 2D systems. We show they are not suitable for these nanostructures and pinpoint the origin of some discrepancies in the elastic properties and effective thicknesses reported in the literature. In an attempt to recover one of these formulas, we introduce an effective torsional thickness for graphene analogous to the effective bending thickness found in the literature. Our results could be useful for fitting interatomic potentials in molecular mechanics or molecular dynamics models for finite carbon nanostructures, especially near their edges and for twisted systems.
Full article
(This article belongs to the Special Issue Advanced Technologies in Graphene-Based Materials)
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Open AccessArticle
Cocrystal Prediction Based on Deep Forest Model—A Case Study of Febuxostat
by
Jiahui Chen, Zhihui Li, Yanlei Kang and Zhong Li
Crystals 2024, 14(4), 313; https://doi.org/10.3390/cryst14040313 - 28 Mar 2024
Abstract
To aid cocrystal screening, a deep forest-based cocrystal prediction model was developed in this study using data from the Cambridge Structural Database (CSD). The positive samples in the experiment came from the CSD. The negative samples were partly from the failure records in
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To aid cocrystal screening, a deep forest-based cocrystal prediction model was developed in this study using data from the Cambridge Structural Database (CSD). The positive samples in the experiment came from the CSD. The negative samples were partly from the failure records in other papers, and some were randomly generated according to specific rules, resulting in a total of 8576 pairs. Compared with the models of traditional machine learning methods and simple deep neural networks models, the deep forest model has better performance and faster training speed. The accuracy is about 95% on the test set. Febuxostat cocrystal screening was also tested to verify the validity of the model. Our model correctly predicted the formation of cocrystal. It shows that our model is practically useful in practice.
Full article
(This article belongs to the Special Issue Crystallization Process and Simulation Calculation, Second Edition)
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Open AccessArticle
Cationic-Surfactant (CTAB) Assisted Preparation of 2D Graphitic Carbon Nitride (g-C3N4) Sheets Advances Supercapacitive Performance
by
Sagar M. Mane, Aviraj M. Teli, Sonali A. Beknalkar, Deepak R. Patil, Jae Cheol Shin and Jaewoong Lee
Crystals 2024, 14(4), 312; https://doi.org/10.3390/cryst14040312 - 27 Mar 2024
Abstract
The distinct physicochemical characteristics of metal-free graphitic carbon nitride (g-C3N4) are gaining interest in various fields, including energy storage and conversion. However, the electrochemical performance of this material is constrained, owing to its minimal surface area. Incorporating a surfactant
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The distinct physicochemical characteristics of metal-free graphitic carbon nitride (g-C3N4) are gaining interest in various fields, including energy storage and conversion. However, the electrochemical performance of this material is constrained, owing to its minimal surface area. Incorporating a surfactant is one of the ways to resolve the issue of surface area and therefore improve the electrochemical performance of g-C3N4. This research delves into a method aimed at improving the supercapacitive capabilities of 2D g-C3N4 sheets through the implementation of a cationic surfactant, cetyltrimethylammonium bromide (CTAB). Electrochemical studies reveal that the CTAB-assisted g-C3N4 sheets exhibit remarkable improvements in specific capacitance, cyclic stability, and comparative rate capability in relation to pristine g-C3N4. The specific capacitance of g-C3N4 with CTAB exceeds about 28%, which gives 162. 8 F g−1. This value is 117.7 F g−1 for electrode material without CTAB at 0.5 mA cm−2. This improved electrochemical performance can be credited to the heightened surface area, improved electronic conductivity, and optimized charge transfer kinetics facilitated by the CTAB surfactant. We aim to emphasize the enhancement of the overall performance of g-C3N4-based supercapacitors for advanced energy storage systems.
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(This article belongs to the Special Issue Advances in Green Nanocomposites: Design, Characterization and Applications)
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Open AccessArticle
Dual-Channel Underwater Acoustic Topological Rainbow Trapping Based on Synthetic Dimension
by
Jialin Zhong, Li Luo, Jiebin Peng, Yingyi Huang, Quanquan Shi, Jiajun Lu, Haobin Zhang, Feiwan Xie, Fugen Wu, Xin Zhang and Degang Zhao
Crystals 2024, 14(4), 311; https://doi.org/10.3390/cryst14040311 - 27 Mar 2024
Abstract
The concept of “rainbow trapping” has generated considerable interest in wave propagation and energy harvesting, offering new possibilities for diverse and efficient acoustic wave operations. In this work, we investigate a dual-channel topological rainbow trapping device implemented within an underwater two-dimensional phononic crystal
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The concept of “rainbow trapping” has generated considerable interest in wave propagation and energy harvesting, offering new possibilities for diverse and efficient acoustic wave operations. In this work, we investigate a dual-channel topological rainbow trapping device implemented within an underwater two-dimensional phononic crystal based on synthetic dimension. The topological edge states with different frequencies are separated and trapped at different spatial locations. Acoustic waves propagate simultaneously along two boundaries due to the degeneracy of the edge states. In particular, the propagation of a dual-channel topological rainbow is also realized by using a bend design. This work contributes to the advancement of multi-channel devices in synthetic space and provides a reference for the design of highly efficient underwater acoustic devices.
Full article
(This article belongs to the Special Issue Crystalline Materials: From Structure to Applications)
Open AccessArticle
Two New Energetic Hexagonal Anti-Perovskites (N2H5)3X[B12H12] · H2O (X− = [NO3]− and [ClO4]−): Crystal Structure, Vibrational Spectra, and Thermal Decomposition
by
Rouzbeh Aghaei Hakkak, Thomas M. Klapötke and Thomas Schleid
Crystals 2024, 14(4), 310; https://doi.org/10.3390/cryst14040310 - 27 Mar 2024
Abstract
Two novel energetic anti-perovskite compounds with the chemical formula (N2H5)3X[B12H12] · H2O, where X− is either [NO3]− or [ClO4]−, were successfully
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Two novel energetic anti-perovskite compounds with the chemical formula (N2H5)3X[B12H12] · H2O, where X− is either [NO3]− or [ClO4]−, were successfully synthesized. Both dodecahydro-closo-dodecaborates crystallize orthorhombically in the space group Cmc21, exhibiting relatively similar lattice parameters ((N2H5)3[NO3][B12H12] · H2O: a = 915.94(5), b = 1817.45(9), c = 952.67(5) pm, (N2H5)3[ClO4][B12H12] · H2O: a = 1040.51(6), b = 1757.68(9), c = 942.34(5) pm both for Z = 4). Their synthesis involved a two-step process: first, Cs2[B12H12] passed through a cation exchange column to yield the acidic form of the dodecahydro-closo-dodecaborate, (H3O)2[B12H12]. This aqueous solution was subsequently neutralized with hydrazinium hydroxide and mixed with the corresponding water-dissolved hydrazinium salt (nitrate or perchlorate). Characterization of the obtained crystals was performed by single-crystal X-ray diffraction and Raman spectroscopy as well as thermal analyses (TG-DTA and DSC). The crystal structure determinations revealed that both compounds adopt a hexagonal anti-perovskite structure, distorted by the presence of water molecules. These compounds containing oxidizing oxoanions demonstrate a remarkable ability to release large amounts of energy (almost 2100 J/g) upon thermal decomposition.
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(This article belongs to the Section Materials for Energy Applications)
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Open AccessArticle
Wood-Derived Graphite: A Sustainable and Cost-Effective Material for the Wide Range of Industrial Applications
by
Young Soon Kim, Md. Abu Hanif, Hyeonjin Song, Sungeun Kim, Yonu Cho, Seung-Kon Ryu and Hong Gun Kim
Crystals 2024, 14(4), 309; https://doi.org/10.3390/cryst14040309 - 27 Mar 2024
Abstract
The study explored the graphitization of wood through two distinct methods: a high-temperature approach at 2400 °C and a low-temperature technique at 1400 °C using a catalyst. The graphitization properties were assessed by conducting thermal experiments at various temperatures (1100 °C, 1400 °C,
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The study explored the graphitization of wood through two distinct methods: a high-temperature approach at 2400 °C and a low-temperature technique at 1400 °C using a catalyst. The graphitization properties were assessed by conducting thermal experiments at various temperatures (1100 °C, 1400 °C, 1800 °C, 2000 °C, and 2400 °C), both with and without a catalyst. The development of graphite lattices was quantitatively analyzed using an array of techniques: X-ray diffractometer (XRD), Raman spectroscopy, high-resolution transmission electron microscopy (HR-TEM), and Fourier transform infrared spectroscopy (FTIR). The XRD analysis highlighted temperature-dependent changes in lattice parameters (d002, La, and Lc), while Raman spectroscopy tracked alterations in the D to G peak ratio (D/G) with temperature. An increase in temperature is correlated with a rise in the number of graphene layers and the degree of graphitization. Notably, the process of graphite lattice formation varied across the experimental temperature spectrum. The use of a catalyst resulted in a reduced d002 spacing, signifying an enhanced degree of graphitization. Moreover, the catalyst promoted a consistent and smooth graphitization process throughout the heating stages. In contrast, graphitization without a catalyst occurred at higher temperatures, specifically between 1800 °C and 2000 °C, with the d002 value stabilizing around 0.338 nm. The catalyst proved instrumental in transforming the initial structure into well-ordered graphite at lower temperatures. This investigation underscores the potential and benefits of employing a catalyst to generate high-quality graphite from wood at reduced temperatures, paving the way for sustainable and economically viable applications of this material.
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(This article belongs to the Section Inorganic Crystalline Materials)
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Open AccessArticle
Effect of Particle Concentration on the Microstructure and Properties of Electrodeposited Nickel–Diamond Composite Coatings
by
Zhiyuan Yang, Kunxiang Ge, Wen Cai, Shenqiang Liu, Shitao Zhang, Zhengyang Pan, Jianing Zhang, Yuantao Zhao, Wenge Li and Yanbo Liu
Crystals 2024, 14(4), 308; https://doi.org/10.3390/cryst14040308 - 27 Mar 2024
Abstract
For the purpose of improving the wear properties of Ni composite coatings, diamond particles were co-electrodeposited into Ni–diamond composite coatings. The effect of diamond particle concentration in the electrolyte on the surface morphology, microstructure, and wear properties of Ni–diamond composite coatings was investigated.
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For the purpose of improving the wear properties of Ni composite coatings, diamond particles were co-electrodeposited into Ni–diamond composite coatings. The effect of diamond particle concentration in the electrolyte on the surface morphology, microstructure, and wear properties of Ni–diamond composite coatings was investigated. The electrodeposition behaviors of the composite coatings were simulated by COMSOL5.6. The results showed that the content of diamond particles in the coating was elevated by increasing the particle concentration in the electrolyte. The formation of [200] fiber texture was blocked and concurrently brought about crystallite refinement of the Ni deposits by the embedded particles. The COMSOL simulation findings indicated that embedded particles influenced the microstructure of the Ni deposits through processes such as heterogeneous nucleation, rearrangement, and concentration of local current density. The synergistic effect of the tailored microstructure and embedded particles substantially enhanced the wear resistance of the coating. By increasing the particle concentration in the electrolyte, the wear resistance of the coating was gradually enhanced, and the coating electrodeposited at 16 g/L possessed the lowest friction coefficient and the smallest profile of wear scratch owning to the strengthened synergistic effect.
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(This article belongs to the Special Issue Additive Manufacturing: Experiments, Simulations and Data-Driven Modelling)
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Open AccessCommunication
A Study of the Hot Salt Corrosion Behavior of Three Nickel-Based Single-Crystal Superalloys at 900 °C
by
Qianyi Li, Feng Liu, Yixin Li, Jian Yao, Jingyu Yang, Liming Tan, Zi Wang, Lan Huang and Yong Liu
Crystals 2024, 14(4), 307; https://doi.org/10.3390/cryst14040307 - 27 Mar 2024
Abstract
A study of the hot salt corrosion behavior of three nickel-based single-crystal superalloys at 900 °C was conducted. We discovered that the corrosion layer on each alloy was distinctly enriched with Mo, Ni, S, and O, primarily comprising sulfides and oxides. Notably, variations
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A study of the hot salt corrosion behavior of three nickel-based single-crystal superalloys at 900 °C was conducted. We discovered that the corrosion layer on each alloy was distinctly enriched with Mo, Ni, S, and O, primarily comprising sulfides and oxides. Notably, variations in oxygen distribution across the alloys revealed that the elemental composition plays a pivotal role in their corrosion resistance. These insights not only advance our understanding of the mechanisms driving thermal corrosion in nickel-based single-crystal superalloys but also lay the groundwork for designing alloys with enhanced durability tailored to high-temperature applications. This research marks a significant step toward the optimal design and utilization of superalloys in sectors demanding exceptional material stability under thermal stress.
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(This article belongs to the Special Issue Hot Corrosion and Oxidation of Alloys)
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Open AccessReview
Nanostructured Materials for Enhanced Performance of Solid Oxide Fuel Cells: A Comprehensive Review
by
Hicham Helal, Mohammadi Ahrouch, Abdelaziz Rabehi, Dario Zappa and Elisabetta Comini
Crystals 2024, 14(4), 306; https://doi.org/10.3390/cryst14040306 - 26 Mar 2024
Abstract
Solid oxide fuel cells (SOFCs) have emerged as promising candidates for efficient and environmentally friendly energy conversion technologies. Their high energy conversion efficiency and fuel flexibility make them particularly attractive for various applications, ranging from stationary power generation to portable electronic devices. Recently,
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Solid oxide fuel cells (SOFCs) have emerged as promising candidates for efficient and environmentally friendly energy conversion technologies. Their high energy conversion efficiency and fuel flexibility make them particularly attractive for various applications, ranging from stationary power generation to portable electronic devices. Recently, research has focused on utilizing nanostructured materials to enhance the performance of SOFCs. This comprehensive review summarizes the latest advancements in the design, fabrication, and characterization of nanostructured materials integrated in SOFC. The review begins by elucidating the fundamental principles underlying SOFC operation, emphasizing the critical role of electrode materials, electrolytes, and interfacial interactions in overall cell performance, and the importance of nanostructured materials in addressing key challenges. It provides an in-depth analysis of various types of nanostructures, highlighting their roles in improving the electrochemical performance, stability, and durability of SOFCs. Furthermore, this review delves into the fabrication techniques that enable precise control over nanostructure morphology, composition, and architecture. The influence of nanoscale effects on ionic and electronic transport within the electrolyte and electrodes is thoroughly explored, shedding light on the mechanisms behind enhanced performance. By providing a comprehensive overview of the current state of research on nanostructured materials for SOFCs, this review aims to guide researchers, engineers, and policymakers toward the development of high-performance, cost-effective, and sustainable energy conversion systems.
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(This article belongs to the Special Issue Advances of Solid Oxide Fuel Cells)
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Investigation on Friction Stir Welding Parameters: Mechanical Properties, Correlations and Corrosion Behaviors of Aluminum/Titanium Dissimilar Welds
by
Amlan Kar, Sribalaji Mathiyalagan, Sergey Malopheyev, Rustam Kaibyshev, Satyam Suwas and Satish V. Kailas
Crystals 2024, 14(4), 305; https://doi.org/10.3390/cryst14040305 - 26 Mar 2024
Abstract
In industrial applications, welding of dissimilar metals such as aluminum (Al) and titanium (Ti) is a prerequisite for the development of hybrid components with improved mechanical and corrosion properties. However, dissimilar welding of the Al/Ti system is highly challenging due to differences in
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In industrial applications, welding of dissimilar metals such as aluminum (Al) and titanium (Ti) is a prerequisite for the development of hybrid components with improved mechanical and corrosion properties. However, dissimilar welding of the Al/Ti system is highly challenging due to differences in the physical and thermal properties of the two materials. In the present investigation, an attempt has been made to fabricate a dissimilar friction stir weld (FSW) of commercially pure Al and Ti and to elucidate the mechanism associated with superior joint formation. The process parameters, such as tool rotation speed, traverse speed and tool offset position have been optimized using Taguchi’s optimization technique. A detailed investigation of the weld with optimum process parameters has been carried out to reveal the mechanism of joint formation. The superior mechanical properties (24% higher ultimate tensile strength and 10% higher ductility than that of base Al) of the weld are attributed to the fabrication of a defect-free joint, formation of intercalated particles and an Al/Ti interlocking interface, homogeneous distribution of fine second-phase (Ti and/or intermetallics) particles in the weld nugget, reduction in the evolution of brittle Al3Ti intermetallic compounds (IMCs) and recrystallization and grain refinement of Al in the weld nugget. The potentio-dynamic polarization test indicated that the optimized Al/Ti weld has ~47% higher corrosion resistance than Al; it had a very mild corrosion attack due to the homogeneous dispersion of fine particles. The method and mechanism could have an immense influence on any dissimilar weld and metal matrix composites, improving their mechanical properties and corrosion resistance.
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(This article belongs to the Special Issue Microstructure and Mechanical Properties of Welding Joints)
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Open AccessArticle
The Effect of Sputtering Target Density on the Crystal and Electronic Structure of Epitaxial BaTiO3 Thin Films
by
Fugang Qi, Shaoqin Peng, Jiachang Bi, Shunda Zhang, Guanhua Su, Peiyi Li, Jiahui Zhang, Tengteng Zhang, Weisong Zhou, Ruyi Zhang and Yanwei Cao
Crystals 2024, 14(4), 304; https://doi.org/10.3390/cryst14040304 - 26 Mar 2024
Abstract
Barium titanate (BaTiO3) is a promising material for silicon-integrated photonics due to its large electro-optical coefficients, low loss, high refractive index, and fast response speed. Several deposition methods have been employed to synthesize BaTiO3 films. Magnetron sputtering is one of
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Barium titanate (BaTiO3) is a promising material for silicon-integrated photonics due to its large electro-optical coefficients, low loss, high refractive index, and fast response speed. Several deposition methods have been employed to synthesize BaTiO3 films. Magnetron sputtering is one of these methods, which offers specific advantages for growing large-scale films. However, there is a scarcity of studies investigating the effect of sputtering target density on the quality of BaTiO3 films. Therefore, this study aims to uncover the effect of sputtering targets on the crystal and electronic structures of epitaxial BaTiO3 thin films. Two BaTiO3 ceramic targets were sintered at different densities by altering the sintering temperatures. The crystal structure and chemical composition of the targets were then characterized using X-ray diffraction, Raman spectroscopy, and scanning electron microscopy with energy-dispersive X-ray spectroscopy. Subsequently, BaTiO3 epitaxial films were grown by magnetron sputtering using these two targets. The crystal and electronic structures of the BaTiO3 films were analyzed using high-resolution X-ray diffraction, X-ray photoemission spectroscopy, atomic force microscopy, and spectroscopic ellipsometry. Notably, the BaTiO3 films grown with high-density targets show superior quality but contain oxygen vacancies, whereas those films synthesized with low-density targets display high surface roughness. These findings provide insights into the effect of sputtering target density on the crystal and electronic structures of epitaxial BaTiO3 thin films.
Full article
(This article belongs to the Special Issue Epitaxial Growth and Application of Metallic Oxide Thin Films)
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Open AccessArticle
Weldability of Additively Manufactured Powder Bed Fusion 316L Stainless Steel Using Arc and Laser Welding
by
Koen Faes, Rafael Nunes, Florian Probst, Robin Ceuppens and Wim De Waele
Crystals 2024, 14(4), 303; https://doi.org/10.3390/cryst14040303 - 25 Mar 2024
Abstract
The use of additive manufacturing for metallic materials presents a wide range of possibilities for industrial applications. The technology offers several advantages, including weight optimisation and the ability to create complex geometries. However, because of the inherent characteristics of the manufacturing process, the
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The use of additive manufacturing for metallic materials presents a wide range of possibilities for industrial applications. The technology offers several advantages, including weight optimisation and the ability to create complex geometries. However, because of the inherent characteristics of the manufacturing process, the dimensions of the produced objects are frequently constrained. In some cases, it may be necessary to join two additively manufactured parts together or to join such parts with an existing, conventionally manufactured structure. Evaluating welding processes for joining additively manufactured workpieces is a crucial step in this development. In this work, the welding of additively manufactured powder bed fusion 316L stainless steel components is discussed. The welding processes considered are manual TIG, manual and robotic MIG/MAG and laser welding. All optimised welds were of good quality and did not show any weld imperfections. All welds fulfil the requirements of standard ISO 15614-1 for the tensile and bend test results and for the hardness values. It can be concluded that the investigated processes are feasible for welding additively manufactured parts.
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(This article belongs to the Special Issue Welding Dissimilar Materials)
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Open AccessArticle
Melamine Cyanaurate Microrods Decorated with SnO2 Quantum Dots for Photoelectrochemical Applications
by
Itheereddi Neelakanta Reddy, Bhargav Akkinepally, Moorthy Dhanasekar, Jaesool Shim and Cheolho Bai
Crystals 2024, 14(4), 302; https://doi.org/10.3390/cryst14040302 - 25 Mar 2024
Abstract
This study employs a simple and cost-effective technique to enhance the photoelectrochemical (PEC) water-splitting performance of melamine cyanaurate microrods (M), SnO2 nanostructures (S), and melamine cyanaurate microrods decorated with SnO2 quantum dots (MS) by optimizing NaOH and Na2SO3
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This study employs a simple and cost-effective technique to enhance the photoelectrochemical (PEC) water-splitting performance of melamine cyanaurate microrods (M), SnO2 nanostructures (S), and melamine cyanaurate microrods decorated with SnO2 quantum dots (MS) by optimizing NaOH and Na2SO3 electrolytes. Notably, the MS electrode demonstrates a remarkable improvement in PEC efficiency in Na2SO3 solution associated with NaOH solution. Specifically, the induced currents of the MS anode in the Na2SO3 electrolyte are approximately 6.28 mAcm−2 more than those observed in the NaOH electrolyte solution. It is revealed that anions effectively consume the holes, leading to improved separation of the generated charge pairs. This effective charge separation mechanism significantly contributes to the enhanced PEC performance observed in Na2SO3 electrolytes. The findings of this study suggest a capable approach for improving the PEC activity of the materials through the careful optimization of the supported electrolytes.
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(This article belongs to the Special Issue Research on Electrolytes and Energy Storage Materials)
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Open AccessEditorial
Recent Developments in Multifunctional Coordination Polymers
by
Ileana Dragutan, Fu Ding, Yaguang Sun and Valerian Dragutan
Crystals 2024, 14(4), 301; https://doi.org/10.3390/cryst14040301 - 25 Mar 2024
Abstract
This Special Issue of Crystals “Multifunctional Coordination Polymers: Synthesis, Structure, Properties and Applications” [...]
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(This article belongs to the Special Issue Multifunctional Coordination Polymers: Synthesis, Structure, Properties and Applications)
Open AccessArticle
Potential of Y2Sn2O7:Eu3+, Dy3+ Inorganic Nanophosphors in Latent Fingermark Detection
by
Layla Brini, Hanen Douiri, Marwa Abid, Alessandra Toncelli, Montasir Qasymeh, Ramzi Maalej and Mohamed Abdelhedi
Crystals 2024, 14(4), 300; https://doi.org/10.3390/cryst14040300 - 24 Mar 2024
Abstract
In this work, we investigated the potential of Eu3+/Dy3+-codoped Y2Sn2O7 fluorescent nanophosphors to visualize latent fingermarks. We prepared these nanophosphors with various doping concentrations by the conventional coprecipitation reaction. The crystal structure, morphology, luminescence
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In this work, we investigated the potential of Eu3+/Dy3+-codoped Y2Sn2O7 fluorescent nanophosphors to visualize latent fingermarks. We prepared these nanophosphors with various doping concentrations by the conventional coprecipitation reaction. The crystal structure, morphology, luminescence properties, and energy transfer mechanisms were studied. The crystalline phase was characterized by X-ray diffraction and crystal structure refinement using the Rietveld method. XRD measurements showed that the samples crystallized in the pure single pyrochlore phase with few more peaks originated from secondary phases and impurities generated during phosphor production, and that Eu3+ ions occupied D3d symmetry sites. The average crystallite size after mechanical grinding was less than 100 nm for all compositions. The optical characterization showed that, when excited under 532 nm, the Eu3+/Dy3+-codoped Y2Sn2O7 samples’ main intense emission peaks were located at 580–707 nm, corresponding to the 5D0→7Fj (j = l, 2, 3, and 4) transitions of europium. In fact, the 5D0→7F2 hypersensitive transition is strongly dependent on the local environment and was quite weak in Eu3+:Y2Sn2O7 at low Eu3+ doping levels. We found that the presence of Dy3+ as a codopant permitted enhancing the emission from this transition. The calculated PL CIE coordinates for the synthesized nanophosphors were very close to those of the reddish-orange region and only slightly dependent on the doping level. Various surfaces, including difficult ones (wood and ceramic), were successfully tested for latent fingerprint development with the prepared Eu3+/Dy3+-codoped Y2Sn2O7 fluorescent nanophosphor powder. Thanks to the high contrast obtained, fingerprint ridge patterns at all three levels were highlighted: core (level 1) islands, bifurcation, and enclosure (level 2), and even sweat pores (level 3).
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(This article belongs to the Special Issue Optical and Spectroscopic Properties of Rare-Earth-Doped Crystals (2nd Edition))
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Open AccessArticle
Magnetoelectric Properties of Aurivillius-Layered Perovskites
by
Vadla Veenachary, Eskilla Venkata Ramana, Simhachalam Narendra Babu, Venkata Sreenivas Puli, Sujoy Saha, Gopalan Srinivasan, G. Prasad and N. V. Prasad
Crystals 2024, 14(4), 299; https://doi.org/10.3390/cryst14040299 - 22 Mar 2024
Abstract
In the present work, we have synthesized rare-earth ion modified Bi4−xRExTi2Fe0.7Co0.3O12−δ (RE = Dy, Sm, La) multiferroic compounds by the conventional solid-state route. Analysis of X-ray diffraction by Rietveld refinement confirmed the
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In the present work, we have synthesized rare-earth ion modified Bi4−xRExTi2Fe0.7Co0.3O12−δ (RE = Dy, Sm, La) multiferroic compounds by the conventional solid-state route. Analysis of X-ray diffraction by Rietveld refinement confirmed the formation of a polycrystalline orthorhombic phase. The morphological features revealed a non-uniform, randomly oriented, plate-like grain structure. The peaks evident in the Raman spectra closely corresponded to those of orthorhombic Aurivillius phases. Dielectric studies and impedance measurements were carried out. Asymmetric complex impedance spectra suggested the relaxation of charge carriers belonging to the non-Debye type and controlled by a thermally activated process. Temperature-dependent AC conductivity data showed a change of slope in the vicinity of the phase transition temperature of both magnetic and electrical coupling natures. Based on the universal law and its exponent nature, one can suppose that the conduction process is governed by a small polaron hopping mechanism but significant distortion of TiO6 octahedral. The doping of the A-sites with rare-earth element ions and changes in the concentrations of Fe and Co ions located on the B-sites manifested themselves in saturated magnetic hysteresis loops, indicating competitive interactions between ferroelectric and canted antiferromagnetic spins. The magnetic order in the samples is attributed to pair-wise interactions between adjacent Fe3+–O–Fe3+, Co2+/3+–O–Co3+/2+, and Co2+/3+–O–Fe3+ ions or Dzyaloshinskii–Moriya interactions among magnetic ions in the adjacent sub-lattices. As a result, enhanced magnetoelectric coefficients of 42.4 mV/cm-Oe, 30.3 mV/cm-Oe, and 21.6 mV/cm-Oe for Bi4−xDyxTi2Fe0.7Co0.3O12−δ (DBTFC), Bi4−xLaxTi2Fe0.7Co0.3O12−δ (LBTFC), and Bi4−xSmxTi2Fe0.7Co0.3O12−δ (SBTFC), respectively, have been obtained at lower magnetic fields (<3 kOe). The strong coupling of the Aurivillius compounds observed in this study is beneficial to future multiferroic applications.
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(This article belongs to the Special Issue Advanced Ferroelectric, Piezoelectric and Dielectric Ceramics)
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Open AccessArticle
Online Defect Detection in LGA Crystallization Imaging Using MANet-Based Deep Learning Image Analysis
by
Yan Huo, Diyuan Guan and Lingyan Dong
Crystals 2024, 14(4), 298; https://doi.org/10.3390/cryst14040298 - 22 Mar 2024
Abstract
In this paper, a MANet-based image detection approach is designed to inspect crystal defects during the cooling crystallization process, like that involving β-form L-glutamic acid (LGA), utilizing an online imaging device. The steps in the presented strategy encompass crystal image preprocessing, crystal image
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In this paper, a MANet-based image detection approach is designed to inspect crystal defects during the cooling crystallization process, like that involving β-form L-glutamic acid (LGA), utilizing an online imaging device. The steps in the presented strategy encompass crystal image preprocessing, crystal image segmentation, and crystal classification. Firstly, the guided image filter is introduced to preprocess the collected crystallization images for offline training and online detection. Then, by using an image augmentation strategy to enlarge the number of crystal image samples for training, the MANet-based network is improved for crystal image segmentation. Accordingly, by defining some features, needle-like crystals can be categorized into four types with an efficient classifier for the detection of normal and defective crystals. The experimental results for the batch crystallization of β-form LGA are provided to illustrate the validity of the presented detection methodology.
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(This article belongs to the Section Inorganic Crystalline Materials)
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