Disordered Crystalline Materials

A special issue of Crystals (ISSN 2073-4352). This special issue belongs to the section "Inorganic Crystalline Materials".

Deadline for manuscript submissions: closed (28 February 2021) | Viewed by 9561

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Department of Electronic Engineering, Chung Yuan Christian University, Zhongli District, Taoyuan City, Taiwan
Interests: 2D materials; spintronics; quantum transport; condensed matter physics; Dirac semimetal; magnetism

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School of Engineering and Materials Science, Materials Research Institute, Queen Mary University of London, Mile End Rd, Bethnal Green, London E1 4NS, UK
Interests: preparation of functional carbon nanocomposites and photoluminescent carbon nanomaterials; semiconductor micro/nanoparticles; biosensing; oxygen and hydrogen electrocatalysis; carbon dioxide reduction; photocatalysis
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University of Sussex, Sussex, UK

Special Issue Information

Dear Colleagues,

“Disordered” in condensed matter physics and materials are more and more important since Prof. P. W. Anderson, S. N. F. Mott and J. H. van Vleck won the Nobel Prize in Physics 1977 for their fundamental theoretical investigations of the electronic structure of magnetic and disordered systems. Perfect crystal in materials are difficulty to grow and fabricate, therefore they would happen some defects, impurities, lattice mismatch, grain boundaries and so on, that could be called disorder situations in crystalline material. Such fiend about disordered crystalline materials is a rapidly progressing field of solid-state science, comprising chemists, biomedical engineering and experimental and theoretical physicists from all around the world. Although low-dimensional materials and topological insulators have gained enormous interest in recent years; however, disordered physics behaviors are still unclear in this field. Especially, what do we know the rules about the effect of disorder in disordered crystalline materials? Can we enhance the conductivity, magnetism, superconductivity, spintronic current by tuning the disordered situations in crystalline materials? Researchers are still working at fundamental problems about disordered situations, but perfect crystal are not out of reach. This fields are currently core, open questions, developments and novelty topics in condensed matter physics and nanotechnology.

Dr. Chiashain Chuang
Dr. Arun Prakash Periasamy
Dr. Reuben K. Puddy
Guest Editors

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Keywords

  • Semiconductors
  • Graphene
  • Magnetic systems
  • Carrier transport
  • Solid-state physics and chemistry
  • Crystalline interface

Published Papers (4 papers)

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Research

12 pages, 3222 KiB  
Article
Impact of Disorder on Properties of Vacancies: A Case Study of B2 and A2 Polymorphs of Non-Stoichiometric Fe2CoAl
by Martin Friák, Jana Pavlů and Mojmír Šob
Crystals 2021, 11(10), 1207; https://doi.org/10.3390/cryst11101207 - 7 Oct 2021
Cited by 3 | Viewed by 1898
Abstract
We have performed an ab initio study of vacancy-induced changes in thermodynamic, structural and magnetic properties of single-phase ferromagnetic Fe2CoAl with a chemically disordered (i) two-sublattice B2 phase or (ii) single-sublattice A2 phase. The two polymorphs of slightly non-stoichiometric Fe2 [...] Read more.
We have performed an ab initio study of vacancy-induced changes in thermodynamic, structural and magnetic properties of single-phase ferromagnetic Fe2CoAl with a chemically disordered (i) two-sublattice B2 phase or (ii) single-sublattice A2 phase. The two polymorphs of slightly non-stoichiometric Fe2CoAl (Fe27Co14Al13) were modeled by two different 54-atom supercells with atoms distributed according to the special quasi-random structure (SQS) concept. Both the lower-energy B2 phase and a higher-energy A2 phase possess elastic constants that correspond to an auxetic material that is mechanically stable. The properties of vacancies were computed by systematically removing different atoms (one at a time) from the supercells and quite wide ranges of values of vacancy-related characteristics were obtained. The increase in the level of disorder (when changing from the B2 to the A2 phase) results in an increase in the scatter of calculated values. The Fe and Co vacancies have lower vacancy formation energies than the Al ones. The total magnetic moment of the supercell decreases when introducing Fe and Co vacancies but it increases due to Al ones. The latter findings can be partly explained by an increase of the local magnetic moment of Fe atoms when the number of Al atoms in the first neighbor shell of Fe atoms is reduced, such as due to Al vacancies. Full article
(This article belongs to the Special Issue Disordered Crystalline Materials)
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11 pages, 3209 KiB  
Article
Stability, Elastic and Electronic Properties of Ta2N by First-Principles Calculations
by Longpeng Zhu, Jiong Wang, Chenchen Dong, Yong Du, Shun-Li Shang and Zi-Kui Liu
Crystals 2021, 11(4), 445; https://doi.org/10.3390/cryst11040445 - 19 Apr 2021
Cited by 4 | Viewed by 2247
Abstract
Owing to exploring the influence of the N atoms ordering in Ta2N compounds on their properties, the stability, elastic, and electronic properties of Ta2N compounds (Ta2N-I: P3¯ml and Ta2N-II: P [...] Read more.
Owing to exploring the influence of the N atoms ordering in Ta2N compounds on their properties, the stability, elastic, and electronic properties of Ta2N compounds (Ta2N-I: P3¯ml and Ta2N-II: P3¯1m) were investigated using first-principles calculations based on density functional theory. Ta2N-II is energetically favorable according to the enthalpy of formation. Elastic constants were employed to reveal the stronger resistance to deformation, but weaker anisotropy, in Ta2N-II. A ductile-brittle transition was found between Ta2N-I (ductile) and Ta2N-II (brittle). The partial density of states showed a stronger orbital hybridization of Ta-d and N-p in Ta2N-II, resulting in stronger covalent bonding. The charge density difference illustrated the interaction of the Ta-N bond and electron distribution of Ta2N. Full article
(This article belongs to the Special Issue Disordered Crystalline Materials)
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13 pages, 2821 KiB  
Article
A Characteristic Study of Polylactic Acid/Organic Modified Montmorillonite (PLA/OMMT) Nanocomposite Materials after Hydrolyzing
by Su-Mei Huang, Jiunn-Jer Hwang, Hsin-Jiant Liu and An-Miao Zheng
Crystals 2021, 11(4), 376; https://doi.org/10.3390/cryst11040376 - 3 Apr 2021
Cited by 7 | Viewed by 2245
Abstract
In this study, the montmorillonite (MMT) clay was modified with NH4Cl, and then the structures were exfoliated or intercalated in a polylactic acid (PLA) matrix by a torque rheometer in the ratio of 0.5, 3.0, 5.0 and 8.0 wt%. X-ray diffraction [...] Read more.
In this study, the montmorillonite (MMT) clay was modified with NH4Cl, and then the structures were exfoliated or intercalated in a polylactic acid (PLA) matrix by a torque rheometer in the ratio of 0.5, 3.0, 5.0 and 8.0 wt%. X-ray diffraction (XRD) revealed that the organic modified-MMT(OMMT) was distributed successfully in the PLA matrix. After thermal pressing, the thermal stability of the mixed composites was measured by a TGA. The mixed composites were also blended with OMMT by a co-rotating twin screw extruder palletizing system, and then injected for the ASTM-D638 standard specimen by an injection machine for measuring the material strength by MTS. The experimental results showed that the mixture of organophilic clay and PLA would enhance the thermal stability. In the PLA mixed with 3 wt% OMMT nanocomposite, the TGA maximum decomposition temperature (Tmax) rose from 336.84 °C to 339.08 °C. In the PLA mixed with 5 wt% OMMT nanocomposite, the loss of temperature rose from 325.14 °C to 326.48 °C. In addition, the elongation rate increased from 4.46% to 10.19% with the maximum loading of 58 MPa. After the vibrating hydrolysis process, the PLA/OMMT nanocomposite was degraded through the measurement of differential scanning calorimetry (DSC) and its Tg, Tc, and Tm1 declined. Full article
(This article belongs to the Special Issue Disordered Crystalline Materials)
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16 pages, 5694 KiB  
Article
Evaluation of Growth, Thermal, and Spectroscopic Properties of Er3+-Doped CLNGG Crystals for Use in 2.7 μm Laser
by Kaiyang Tang, Shawuti Yingming, Jinggang Gai and Zhongben Pan
Crystals 2021, 11(2), 126; https://doi.org/10.3390/cryst11020126 - 27 Jan 2021
Cited by 3 | Viewed by 1857
Abstract
A series of optical-quality Er3+-doped calcium lithium niobium gallium garnet (CLNGG) single crystals with different Er3+ ion concentration (10, 15 and 30 at.%) has been grown by the Czochralski method. A comparative study of their structure, thermal, and spectroscopic properties [...] Read more.
A series of optical-quality Er3+-doped calcium lithium niobium gallium garnet (CLNGG) single crystals with different Er3+ ion concentration (10, 15 and 30 at.%) has been grown by the Czochralski method. A comparative study of their structure, thermal, and spectroscopic properties is performed. Crystal structure was analyzed with X-ray powder diffraction (XRPD) and refined by the Rietveld method, results showing that the Er:CLNGG crystal possesses a cubic structure with space group Ia3¯d, and the lattice constants decrease linearly as the Er3+ concentration increase. The complete set of thermal properties were systematically studied for the first time. It has been found that all the thermal conductivities increase with temperature, indicating a glass-like behavior. Effect of Er3+ concentration on spectroscopic properties of Er:CLNGG crystals was studied. Results show that with the Er3+ concentration increase, the NIR fluorescence around 1600 nm weakens, while the Mid-IR fluorescence intensity around 2700 nm strengthens. Fluorescence lifetime of 4I13/2 decreased faster than that of 4I11/2 with the Er3+ concentration increase, which is beneficial for surmounting the “bottleneck” effect to achieve 2.7 μm laser. All the results show that CLNGG crystal with high Er3+ concentration is a potential candidate for the 2.7 μm laser. Full article
(This article belongs to the Special Issue Disordered Crystalline Materials)
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