Editorial

4 pages, 178 KiB

Open AccessEditorial

Magnetic, Dielectric, Electrical, Optical and Thermal Properties of Crystalline Materials

by Mohamed Khitouni and Joan-Josep Suñol

Crystals 2024, 14(3), 252; https://doi.org/10.3390/cryst14030252 - 04 Mar 2024

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This Special Issue entitled “Magnetic, Dielectric, Electrical, Optical and Thermal Properties of Crystalline Materials” is devoted to a general overview of the subject of crystalline materials and may extend to the nanocrystalline field [...] Full article

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

Research

Jump to: Editorial

13 pages, 2275 KiB

Open AccessArticle

Theoretical Investigations of the Structural, Dynamical, Electronic, Magnetic, and Thermoelectric Properties of CoMRhSi (M = Cr, Mn) Quaternary Heusler Alloys

by Abdullah Hzzazi, Hind Alqurashi, Eesha Andharia, Bothina Hamad and M. O. Manasreh

Crystals 2024, 14(1), 33; https://doi.org/10.3390/cryst14010033 - 27 Dec 2023

Cited by 1 | Viewed by 827

Abstract

The structural, dynamical, electrical, magnetic, and thermoelectric properties of CoMRhSi (M = Cr, Mn) quaternary Heusler alloys (QHAs) were investigated using density functional theory (DFT). The Y-type-II crystal structure was found to be the most stable configuration for these QHAs. [...] Read more.

The structural, dynamical, electrical, magnetic, and thermoelectric properties of CoMRhSi (M = Cr, Mn) quaternary Heusler alloys (QHAs) were investigated using density functional theory (DFT). The Y-type-II crystal structure was found to be the most stable configuration for these QHAs. Both CoCrRhSi and CoMnRhSi alloys possess a half-metallic behavior with a 100% spin-polarization as the majority spin channel is metallic. On the other hand, the minority spin channel is semiconducting with narrow indirect band gaps of 0.54 eV and 0.57 eV, respectively, along the

Γ - X

high symmetry line. In addition, both CoCrRhSi and CoMnRhSi alloys possess a ferromagnetic structure with total magnetic moments of 4 μ_B, and 5 μ_B, respectively, which are prominent for spintronics applications. The thermoelectric properties of the subject QHAs were calculated by using Boltzmann transport theory within the constant relaxation time approximation. The lattice thermal conductivities were also evaluated by Slack’s equation. The predicted values of the figure-of-merit (ZT) for CoCrRhSi and CoMnRhSi were found to be 0.84 and 2.04 at 800 K, respectively, making them ideal candidates for thermoelectric applications. Full article

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

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14 pages, 3022 KiB

Open AccessArticle

Optical, Dielectric, and Electrical Properties of Tungsten-Based Materials with the Formula Li_(2−x)Na_xWO₄ (x = 0, 0.5, and 1.5)

by Moufida Krimi, Mohammed H. Al-Harbi, Abdulelah H. Alsulami, Karim Karoui, Mohamed Khitouni and Abdallah Ben Rhaiem

Crystals 2023, 13(12), 1649; https://doi.org/10.3390/cryst13121649 - 30 Nov 2023

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Abstract

In the present study, three chemical compounds, Li₂WO₄, Li_0.5Na_1.5WO₄, and Li_1.5Na_0.5WO₄, are produced using the solid–solid method. Unlike the compound Li_0.5Na_1.5WO₄, [...] Read more.

In the present study, three chemical compounds, Li₂WO₄, Li_0.5Na_1.5WO₄, and Li_1.5Na_0.5WO₄, are produced using the solid–solid method. Unlike the compound Li_0.5Na_1.5WO₄, which crystallizes in the orthorhombic system with the space group Pmmm, both compounds Li₂WO₄ and Li_1.5Na_0.5WO₄ crystallize in the monoclinic system with the space group P2/m. A morphological analysis reveals that all three compounds have a compact structure with some porosity present. An EDX analysis confirms the chemical composition of the three samples. The optical measurements provide information on the optical gaps and Urbach energies of the materials under consideration. Their dielectric characteristics are investigated in a frequency range of 100–106 Hz and at temperatures ranging from 300 to 600 K. Moreover, this research enables us to determine the ferroelectric transition as well as the type of dielectric material. In this study, an investigation of electrical conductivity was conducted for well-defined temperature and frequency values; which provided us with information about the mechanism of conduction and charge carrier transport models. Full article

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

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21 pages, 5395 KiB

Open AccessArticle

First-Principles Study of the Effect of Sn Content on the Structural, Elastic, and Electronic Properties of Cu–Sn Alloys

by Lingzhi Zhang, Yongkun Li, Rongfeng Zhou, Xiao Wang, Qiansi Wang, Lingzhi Xie, Zhaoqiang Li and Bin Xu

Crystals 2023, 13(11), 1532; https://doi.org/10.3390/cryst13111532 - 24 Oct 2023

Cited by 2 | Viewed by 789

Abstract

In order to explore the mechanism of the influence of Sn contents on the relevant properties of Cu–Sn alloys, the structure, elasticity, electronic, and thermal properties of Cu–Sn alloys doped with different proportions of Sn (3.125 at%, 6.25 at%, and 9.375 at%) were [...] Read more.

In order to explore the mechanism of the influence of Sn contents on the relevant properties of Cu–Sn alloys, the structure, elasticity, electronic, and thermal properties of Cu–Sn alloys doped with different proportions of Sn (3.125 at%, 6.25 at%, and 9.375 at%) were established using the first-principles calculation based on density functional theory. Firstly, their lattice constants and Sn concentration comply with Vegard’s Law. From the mixing enthalpy, it can be seen that Sn atoms can be firmly dissolved in the Cu matrix, and the structure is most stable when the Sn content is 3.125 at%. In addition, the introduction of mismatch strain characterized their solid solution strengthening effect. The elastic and electronic properties showed that when the Sn content is 6.25 at%, the Cu–Sn alloy has the best plasticity and the highest elastic anisotropy; when the Sn content is 3.125 at%, the Cu–Sn alloy is the most stable and has stronger bulk and shear modulus, which was mainly due to a stronger Cu-Cu covalent bond. Finally, the Debye temperature, thermal conductivity, and melting point were calculated. It is estimated that the thermal conductivity of Cu–Sn alloy is relatively good when the Sn content is low. Full article

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

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11 pages, 2005 KiB

Open AccessArticle

Non-Collinear Phase in Rare-Earth Iron Garnet Films near the Compensation Temperature

by Dmitry A. Suslov, Petr M. Vetoshko, Alexei V. Mashirov, Sergei V. Taskaev, Sergei N. Polulyakh, Vladimir N. Berzhansky and Vladimir G. Shavrov

Crystals 2023, 13(9), 1297; https://doi.org/10.3390/cryst13091297 - 23 Aug 2023

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Abstract

The experimental discovery of the suppression effect of the non-collinear phase in strong magnetic fields near the compensation point in ferrimagnetic structures was made. The observations were carried out using the magneto-optical method by creating a lateral temperature gradient in the plane of [...] Read more.

The experimental discovery of the suppression effect of the non-collinear phase in strong magnetic fields near the compensation point in ferrimagnetic structures was made. The observations were carried out using the magneto-optical method by creating a lateral temperature gradient in the plane of the epitaxial films of iron garnets. The non-collinear phase is absent in weak magnetic fields. If an external magnetic field exceeds the first critical value, the non-collinear phase arises near the compensation point. The temperature range of the non-collinear phase expands due to the field increase up to the second critical value. Further field increases conversely reduce the temperature range of the non-collinear phase so that the field above the second critical value causes the disappearance of the non-collinear phase. The effect of the occurrence and suppression of the non-collinear phase is demonstrated on samples of two types of iron garnet films with two and three magnetic sublattices. Phase diagrams of the magnetic states in the vicinity of the critical point are constructed, and it is shown that the region of existence of the non-collinear phase in a two-sublattice magnet is smaller than in a three-sublattice one. Full article

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

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20 pages, 5015 KiB

Open AccessArticle

Preparation and Characterization of Nano-Sized Co(II), Cu(II), Mn(II) and Ni(II) Coordination PAA/Alginate Biopolymers and Study of Their Biological and Anticancer Performance

by Maged S. Al-Fakeh, Munirah S. Alazmi and Yassine EL-Ghoul

Crystals 2023, 13(7), 1148; https://doi.org/10.3390/cryst13071148 - 23 Jul 2023

Cited by 1 | Viewed by 1401

Abstract

Four of the crosslinked sodium alginate and polyacrylic acid biopolymers based nanoscale metal natural polysaccharides, [M(AG-PAA)Cl(H₂O)₃], where M = Co(II), Cu(II), Mn(II) and Ni(II), AG = sodium alginate and PAA = polyacrylic acid, have been synthesized and structurally characterized. [...] Read more.

Four of the crosslinked sodium alginate and polyacrylic acid biopolymers based nanoscale metal natural polysaccharides, [M(AG-PAA)Cl(H₂O)₃], where M = Co(II), Cu(II), Mn(II) and Ni(II), AG = sodium alginate and PAA = polyacrylic acid, have been synthesized and structurally characterized. Because of their numerous biological and pharmacological activities of polysaccharides, including antimicrobial, immunomodulatory, antitumor, antidiabetic, antiviral, antioxidant, hypoglycemic and anticoagulant activities, polysaccharides are one of the near-promising candidates in the biomedical and pharmaceutical fields. The complexity of the polymeric compounds has been verified by carbon and nitrogen analysis, magnetic and conductance measurements, FT-IR spectra, electronic spectral analysis and thermal analysis (DTA, TG). All the synthesized complexes were non-electrolytes with magnetic moments ranging from 1.74 to 5.94 BM. The polymeric complexes were found to be of octahedral geometry. The developed coordination polymeric was found to be crystalline using X-ray powder diffraction examinations, which is confirmed by the SEM analysis. As a result, the crystallite size of all polymeric nanocrystals was in the range of 14 - 69 nm. The test of four compounds exhibits a broad spectrum of antimicrobial activity against both Gram-positive and Gram-negative bacteria and fungal Candida albicans. Using DPPH as a substrate, studies on radical scavenging tests are carried out. The findings demonstrated the antioxidant activities of each complex. In addition, results showed that the two chosen polymeric complexes had a good ability to kill cancer cells in a dose-dependent way. The copper(II) polymeric complex showed to its superior functionality as evidenced by microbial activity. After 72 h of interaction with the normal human breast epithelial cells (MCF10A), the synthesized polymeric compounds of Cu(II) and Co(II) showed exceptional cytocompatibility with the different applied doses. Compared to poly-AG/PAA/Co(II), poly-AG/PAA/Cu(II) exhibits a greater anticancer potential at various polymeric dosages. Full article

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

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14 pages, 4119 KiB

Open AccessArticle

Processing and Investigation of Cd_0.5Zn_0.5Fe_2−xCr_xO₄ (0 ≤ x ≤ 2) Spinel Nanoparticles

by Reem Khalid Alharbi, Noura Kouki, Abdulrahman Mallah, Lotfi Beji, Haja Tar, Azizah Algreiby, Abrar S. Alnafisah and Sobhi Hcini

Crystals 2023, 13(7), 1121; https://doi.org/10.3390/cryst13071121 - 18 Jul 2023

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Abstract

This study presents the synthesis of Cd_0.5Zn_0.5Fe_2−xCr_xO₄ nanoparticles via the sol–gel method, along with a comprehensive characterization of their morphological, structural, infrared, and magnetic properties. The X-ray diffraction pattern confirms the formation of the [...] Read more.

This study presents the synthesis of Cd_0.5Zn_0.5Fe_2−xCr_xO₄ nanoparticles via the sol–gel method, along with a comprehensive characterization of their morphological, structural, infrared, and magnetic properties. The X-ray diffraction pattern confirms the formation of the spinel structure, and the cation distribution is estimated using X-ray analysis and confirmed by magnetization measurements. The crystalline size, ranging from 152 to 189 nm, and lattice parameter, varying from 8.51134 Å to 8.42067 Å, decrease with increasing Cr content. The saturation magnetization decreases from 55 emu/g to 10.8 emu/g, while the remanent magnetization increases (3.5 emu/g ≤ M_r ≤ 6.27 emu/g), and the coercivity increases (82 Oe ≤ H_C ≤ 422.15 Oe) with the addition of Cr ions. Fourier transform infrared (FTIR) spectroscopy reveals two absorption bands at ν₁ and ν₂, located near 600 and 400 cm⁻¹, respectively, which correspond to the vibrations of the metal–oxygen bonds in the spinel structure. Full article

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

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13 pages, 3045 KiB

Open AccessArticle

The Effect of Transition Metals Co-Doped ZnO Nanotubes Based-Diluted Magnetic Semiconductor for Spintronic Applications

by Muhammad Adil Mahmood, Rajwali Khan, Sattam Al Otaibi, Khaled Althubeiti, Sherzod Shukhratovich Abdullaev, Nasir Rahman, Mohammad Sohail and Shahid Iqbal

Crystals 2023, 13(7), 984; https://doi.org/10.3390/cryst13070984 - 21 Jun 2023

Cited by 3 | Viewed by 1045

Abstract

The Impact of Co and Gd on the structural, magnetic and dielectric properties of ZnO nanotubes synthesized by co-precipitation is reported. The results demonstrate that incorporating Co and Gd into ZnO diminished crystallinity while retaining the optimum orientation. The outcomes of transmission electron [...] Read more.

The Impact of Co and Gd on the structural, magnetic and dielectric properties of ZnO nanotubes synthesized by co-precipitation is reported. The results demonstrate that incorporating Co and Gd into ZnO diminished crystallinity while retaining the optimum orientation. The outcomes of transmission electron microscopy and scanning electron microscopy examined that the Co and Gd dopants had no effect on the morphology of the produced nanotubes. It was also discovered that as the frequency and concentration of Gd co-dopant decreased, the dielectric constant and loss values increased. When doping was present, the dielectric constant and ac electrical conductivity response was found to be inversely related. Ultimately, at 300K, Co and Gd co-doped ZnO nanotubes exhibited ferromagnetic properties. When Gd doping was increased to 3%, the ferromagnetic response increased. Since then, increasing the Gd co-doping, the ferromagnetic response decreased. For the same sample (Zn_0.96−xCo_0.04Gd_0.03O nanotubes), the electrical conductivity exhibited also superior to pure and low Gd doped ZnO. Its high ferromagnetism is usually caused by magnetic impurities replaced on the ZnO side. Therefore, considering the behaviour of these nanotubes, it can be sued spin-based electronics. Full article

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

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13 pages, 2821 KiB

Open AccessArticle

Synthesis, Structural and Magnetic Characterization of Superparamagnetic Ni_0.3Zn_0.7Cr_2−xFe_xO₄ Oxides Obtained by Sol-Gel Method

by Abdulrahman Mallah, Fatimah Al-Thuwayb, Mohamed Khitouni, Abdulrahman Alsawi, Joan-Josep Suñol, Jean-Marc Greneche and Maha M. Almoneef

Crystals 2023, 13(6), 894; https://doi.org/10.3390/cryst13060894 - 30 May 2023

Cited by 2 | Viewed by 883

Abstract

The sol-gel process was used to produce ferrite Ni_0.3Zn_0.7Cr_2−xFe_xO₄ compounds with x = 0, 0.4, and 1.6, which were then subsequently calcined at several temperatures up to 1448 K for 48 h in an [...] Read more.

The sol-gel process was used to produce ferrite Ni_0.3Zn_0.7Cr_2−xFe_xO₄ compounds with x = 0, 0.4, and 1.6, which were then subsequently calcined at several temperatures up to 1448 K for 48 h in an air atmosphere. X-ray diffraction (XRD), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), and ⁵⁷Fe Mössbauer spectrometry were used to examine the structure and magnetic characteristics of the produced nanoparticles. A single-phase pure Ni_0.3Zn_0.7Cr_2−xFe_xO₄ nanoparticle had formed. The cubic

F d \bar{3} m

spinel structure contained indexes for all diffraction peaks. The crystallite size is a perfect fit for a value of 165 ± 8 nm. Based on the Rietveld analysis and the VSM measurements, the low magnetization Ms of Ni_0.3Zn_0.7Cr_2−xFe_xO₄ samples was explained by the absence of ferromagnetic Ni²⁺ ions and the occupancy of Zn²⁺ ions with no magnetic moments in all tetrahedral locations. Moreover, because of the weak interactions between Fe³⁺ ions in the octahedral locations, the magnetization of the current nanocrystals is low or nonexistent. According to Mössbauer analyses, the complicated hyperfine structures are consistent with a number of different chemical atomic neighbors, such as Ni²⁺, Zn²⁺, Cr³⁺, and Fe³⁺ species that have various magnetic moments. A Fe-rich neighbor is known to have the highest values of the hyperfine field at Fe sites, while Ni- and Cr-rich neighbors are responsible for the intermediate values and Zn-rich neighbors are responsible for the quadrupolar component. Full article

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

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15 pages, 2689 KiB

Open AccessArticle

Nanostructured Mn–Ni Powders Produced by High-Energy Ball-Milling for Water Decontamination from RB5 Dye

by Wael Ben Mbarek, Mohammed Al Harbi, Bechir Hammami, Mohamed Khitouni, Luisa Escoda and Joan-Josep Suñol

Crystals 2023, 13(6), 879; https://doi.org/10.3390/cryst13060879 - 27 May 2023

Viewed by 1040

Abstract

In this study, the degradation efficiency of Mn-20at%Ni and Mn-30at%Ni particle powders made by melt-spinning and high-energy ball-milling techniques is investigated in relation to the degradation of the azo dye Reactive Black 5. SEM, EDS, and XRD were used to analyze the powders’ [...] Read more.

In this study, the degradation efficiency of Mn-20at%Ni and Mn-30at%Ni particle powders made by melt-spinning and high-energy ball-milling techniques is investigated in relation to the degradation of the azo dye Reactive Black 5. SEM, EDS, and XRD were used to analyze the powders’ morphology, surface elemental composition, and phase structure. An ultraviolet-visible absorption spectrophotometer was used to measure the ball-milled powder’s capacity to degrade, and the collected powders were examined using the FTIR spectroscopy method to identify the substituents in the extract. The impact of MnNi alloy on the azo dye Reactive Black 5′s degradation and its effectiveness as a decolorizing agent were examined as functions of different parameters such as chemical composition, specific surface, and temperature. In comparison to the Mn-30at%Ni alloy, the powdered Mn-20at%Ni particles show better degrading efficiency and a faster rate of reaction. This remarkable efficiency is explained by the configuration of the valence electrons, which promotes more responding sites in the d-band when the Ni content is reduced. Therefore, increased electron transport and a hastened decolorization process are achieved by reducing the Ni concentration of RB5 solution with Mn80 particle powder. Additionally, this difference in their decolorization efficiency is explained by the fact that Mn-20at%Ni has the highest specific surface area of 0.45 m² g⁻¹. As the main result, the functional uses of nanostructured metallic powder particles as organic pollution decolorizers in the textile industry are greatly expanded by our study. Full article

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

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10 pages, 3500 KiB

Open AccessArticle

Room Temperature Ferromagnetic Properties of Ga₁₄N_16−nGd₂C_n Monolayers: A First Principle Study

by Shijian Tian, Libo Zhang, Yuan Liang, Ruikuan Xie, Li Han, Shiqi Lan, Aijiang Lu, Yan Huang, Huaizhong Xing and Xiaoshuang Chen

Crystals 2023, 13(3), 531; https://doi.org/10.3390/cryst13030531 - 20 Mar 2023

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Abstract

Electronic and magnetic properties of Ga₁₄N_16−nGd₂C_n monolayers are investigated by means of the first principle calculation. The generalized gradient approximation (GGA) of the density functional theory with the on-site Coulomb energy U was considered (GGA + [...] Read more.

Electronic and magnetic properties of Ga₁₄N_16−nGd₂C_n monolayers are investigated by means of the first principle calculation. The generalized gradient approximation (GGA) of the density functional theory with the on-site Coulomb energy U was considered (GGA + U). It is found that the total magnetic moment of a Ga₁₄N₁₆Gd₂ monolayer is 14

μ_{B}

with an antiferromagnetic (AFM) phase. C atom substitutional impurity can effectively change the magnetic state of Ga₁₄N_16−nGd₂C_n monolayers to ferromagnetic phases (FM), and the magnetic moment increases by 1

μ_{B}

/1C. The stable FM phase is due to the p-d coupling orbitals between the C-2p and Gd-5d states. Moreover, Curie temperature (T_C) close to room temperature (T_R, 300 K) is observed in the Ga₁₄N₁₆Gd₂C₂ monolayer, and the highest value can reach 261.46 K. In addition, the strain effect has a significant positive effect on the

T_{C}

of the Ga₁₄N_16−nGd₂C_n monolayer, which is much higher than the

T_{R}

, and the highest value is 525.50 K. This provides an opportunity to further explore the application of two-dimensional magnetic materials in spintronic devices. 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, 4573 KiB

Open AccessArticle

Synthesis of a Novel Zinc(II) Porphyrin Complex, Halide Ion Reception, Catalytic Degradation of Dyes, and Optoelectronic Application

by Soumaya Nasri, Mouhieddinne Guergueb, Jihed Brahmi, Youssef O. Al-Ghamdi, Frédérique Loiseau and Habib Nasri

Crystals 2023, 13(2), 238; https://doi.org/10.3390/cryst13020238 - 30 Jan 2023

Viewed by 1884

Abstract

This work describes the synthesis of a novel zinc(II) porphyrin complex, namely [Meso-4α-tetra-(1,2,3-triazolyl)phenylporphyrinato]zinc(II) symbolized by 4α-[Zn(TAzPP)] (4), using the click chemistry approach in the presence of copper iodide. All of the synthetic porphyrin species reported herein were fully characterized [...] Read more.

This work describes the synthesis of a novel zinc(II) porphyrin complex, namely [Meso-4α-tetra-(1,2,3-triazolyl)phenylporphyrinato]zinc(II) symbolized by 4α-[Zn(TAzPP)] (4), using the click chemistry approach in the presence of copper iodide. All of the synthetic porphyrin species reported herein were fully characterized by elemental analysis, infrared spectroscopy, proton nuclear magnetic resonance, UV-visible spectroscopy, and fluorescence. To synthesize the 4α-[Zn(TAzPP)] complex (4), we produced 4α-Meso-tetra-o-nitrophenylporphyrin (H₂T_NO2PP) and 4α-meso-tetra-o-aminophenylporphyrin (4α-H₂TNH₂PP) (1) using known classic literature methods. This 4α atropisomer was converted to 4α-meso-tetra-o-azidophenylporphyrin (4α-H₂TN₃PP) (3) by reaction with sodium nitrite and sodium azide, and then it was metalated by Zn(II), leading to [4α-meso-tetra(2-azidophenyl)porphyrinate]zinc(II) (4α-[Zn(TN₃PP)]) (3). The click chemistry synthetic method was finally used to prepare 4α-[Zn(TAzPP)] (4). This new tetracoordinated zinc(II) porphyrin complex was prepared and characterized in order to: (i) produce a receptor for anion recognition and sensing application for Cl⁻ and Br⁻; (ii) study the catalytic decomposition of rhodamine B (RhB) and methyl orange (MO) dyes; and (iii) determine the electronic characteristics as a photovoltaic device. Complex (4) formed 1:1 complex stoichiometric species with chloride and bromide halides and the average association constants of the 1:1 addicts were ~ 10³. The photodecomposition of RhB and MO dyes in the presence of complex (4) as a catalyst and molecular oxygen showed that complex (4) presented a photodegradation yield of approximately 70% and could be reused for five successive cycles without any obvious change in its catalytic activity. The current-voltage characteristics and impedance spectroscopy measurements of complex (4) confirmed that our zinc(II) metalloporphyrin could be used as a photovoltaic device. Full article

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

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12 pages, 6075 KiB

Open AccessArticle

Effect of Thermal Exposure on Mechanical Properties of Al-Si-Cu-Ni-Mg Aluminum Alloy

by Fanming Chen, Chengwen Liu, Lijie Zuo, Zhiyuan Wu, Yiqiang He, Kai Dong, Guoqing Li and Weiye He

Crystals 2023, 13(2), 236; https://doi.org/10.3390/cryst13020236 - 30 Jan 2023

Cited by 2 | Viewed by 1498

Abstract

The microstructure morphology and evolution of mechanical properties are investigated in this study. The results show that the phases displayed no clear change after thermal exposure at 250 °C for 200 h. The tensile strength of the as-cast alloy showed a downward trend [...] Read more.

The microstructure morphology and evolution of mechanical properties are investigated in this study. The results show that the phases displayed no clear change after thermal exposure at 250 °C for 200 h. The tensile strength of the as-cast alloy showed a downward trend in different degrees with the increase in the tensile temperature, while the influence of elongation was opposite to the tensile strength. In addition, the tensile strength tended to be stable after thermal exposure at 250 °C for 100 h. The main creep mechanism of the as-cast alloy at a low temperature and low stress (T ≤ 250 °C; σ ≤ 40 MPa) is grain-boundary creep. The Monkman–Grant empirical formula was used to fit the relationship between the creep life and the minimum creep rate, and the fitting results are:

t_{r} \cdot {\dot{ε}}_{m i n}^{0.95} = 0.207

. Full article

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

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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 2 | Viewed by 1520

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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10 pages, 1343 KiB

Open AccessArticle

Structural, Mechanical, Electronic, Optical, and Thermodynamic Properties of New Oxychalcogenide A₂O₂B₂Se₃ (A = Sr, Ba; B = Bi, Sb) Compounds: A First-Principles Study

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

Crystals 2023, 13(1), 122; https://doi.org/10.3390/cryst13010122 - 10 Jan 2023

Cited by 3 | Viewed by 1322

Abstract

The structural, mechanical, electronic, and optical characteristics of Alkali chalcogenide and oxychalcogenides, i.e., A

_{2}

O

_{2}

B

_{2}

Se

_{3}

(A = Sr, Ba; B = Bi, Sb), were investigated using density functional theory (DFT). After full relaxation, the obtained structural parameters [...] Read more.

The structural, mechanical, electronic, and optical characteristics of Alkali chalcogenide and oxychalcogenides, i.e., A

_{2}

O

_{2}

B

_{2}

Se

_{3}

(A = Sr, Ba; B = Bi, Sb), were investigated using density functional theory (DFT). After full relaxation, the obtained structural parameters are in good agreement with the experimental parameters. Furthermore, the calculated elastic stiffness

C_{i j}

shows that all of the studied compounds followed the mechanical stability criteria. Ductility for these compounds was analyzed by calculating Pugh’s ratio; we classified the Sr

_{2}

O

_{2}

Bi

_{2}

Se

_{3}

, Sr

_{2}

O

_{2}

Sb

_{2}

Se

_{3}

, and Ba

_{2}

O

_{2}

Bi

_{2}

Se

_{3}

as ductile, and the Ba

_{2}

O

_{2}

Sb

_{2}

Se

_{3}

as brittle. The Debye temperature and acoustic velocity were estimated. In addition, electronic and chemical bonding properties were studied from the analysis of the band structure and density of state. The main features of the valence and conduction bands were analyzed from the partial density of states. Electronic band structures are mainly contributed to by Se-

4 p

and Bi-

6 p

/Sb-

5 p

states. Direct band gaps are 0.90, 0.47, and 0.73 eV for Sr

_{2}

O

_{2}

Bi

_{2}

Se

_{3}

, Sr

_{2}

O

_{2}

Sb

_{2}

Se

_{3}

, and Ba

_{2}

O

_{2}

Sb

_{2}

Se

_{3}

, respectively. The Ba

_{2}

O

_{2}

Bi

_{2}

Se

_{3}

compound has an indirect band gap of 1.12 eV. Furthermore, we interpreted and quantified the optical properties, including the dielectric function, absorption coefficient, optical reflectivity, and refractive index. From the reflectivity spectra, we can state that these compounds will be useful for optical applications. Full article

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

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Open AccessArticle

Microstructure and Kinetics of Thermal Behavior of Martensitic Transformation in (Mn,Ni)Sn Heusler Alloy

by Hanen Rekik, Bechir Hammami, Mohamed Khitouni, Tarek Bachagha, Joan-Josep Suñol and Mahmoud Chemingui

Crystals 2022, 12(11), 1644; https://doi.org/10.3390/cryst12111644 - 16 Nov 2022

Cited by 1 | Viewed by 1044

Abstract

In this work, scanning electron microscopy, X-ray diffraction, and differential scanning calorimetry were used to investigate the solidification structure, thermal behavior, and kinetics of the martensitic transformations of the (Mn,Ni)Sn as-spun and annealed ribbons synthesized by melt-spinning. At room temperature, the as-spun and [...] Read more.

In this work, scanning electron microscopy, X-ray diffraction, and differential scanning calorimetry were used to investigate the solidification structure, thermal behavior, and kinetics of the martensitic transformations of the (Mn,Ni)Sn as-spun and annealed ribbons synthesized by melt-spinning. At room temperature, the as-spun and annealed (Mn,Ni)Sn ribbons exhibited a cubic single-phase Heusler L2₁ structure. The kinetics of the martensitic transformation (MT) was studied, together with their microstructure evolution and cooling rate dependence. The mechanism was also investigated. Additionally, a high dependence between the cooling rates and energy activation (Ea) was detected. A more detailed characterization of MT and account of thermodynamic parameters were examined after annealing. Full article

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

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