First‐Principles Study of Sc1−xTixF3 (x ≤ 0.375): Negative Thermal Expansion, Phase Transition, and Compressibility

Wang, Lei; Wang, Wenwen; Sun, Ying; Deng, Sihao; Shi, Kewen; Lu, Huangjun; Hu, Pengwei; Zhang, Xiaoyun

doi:10.1111/jace.13676

Cited by 20 publications

(20 citation statements)

References 38 publications

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“…To elucidate the unique thermophysical properties of ScF 3 , accurate treatment of lattice dynamics including anharmonic effects is essential. Since the discovery of the large NTE in ScF 3 , several first-principles studies based on density functional theory have reported the CTE calculated within the quasi-harmonic approximation (QHA) [20][21][22]. Since the QHA only accounts for the volume dependence of phonon frequencies and neglects higher-order anharmonicities, however, none of these QHA results correctly reproduced the experimental CTE values.…”

Section: Introductionmentioning

confidence: 99%

First-principles study of phonon anharmonicity and negative thermal expansion in ScF3

Oba

Tadano

Akashi

et al. 2019

Phys. Rev. Materials

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The microscopic origin of the large negative thermal expansion of cubic scandium trifluorides (ScF 3 ) is investigated by performing a set of anharmonic free-energy calculations based on density functional theory. We demonstrate that the conventional quasiharmonic approximation (QHA) completely breaks down for ScF 3 and the quartic anharmonicity, treated nonperturbatively by the self-consistent phonon theory, is essential to reproduce the observed transition from negative to positive thermal expansivity and the hardening of the R 4+ soft mode with heating. In addition, we show that the contribution from the cubic anharmonicity to the vibrational free energy, evaluated by the improved self-consistent phonon theory, is significant and as important as that from the quartic anharmonicity for robust understandings of the temperature dependence of the thermal expansion coefficient. The first-principles approach of this study enables us to compute various thermodynamic properties of solids in the thermodynamic limit with the effects of cubic and quartic anharmonicities. Therefore, it is expected to solve many known issues of the QHA-based predictions particularly noticeable at high temperature and in strongly anharmonic materials. arXiv:1810.08800v4 [cond-mat.mtrl-sci]

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Section: Introductionmentioning

confidence: 99%

First-principles study of phonon anharmonicity and negative thermal expansion in ScF3

Oba

Tadano

Akashi

et al. 2019

Phys. Rev. Materials

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“…ScF 3 has attracted a lot of interest for its negative thermal expansion [16,18,[33][34][35][36][37][38][39][40]. The crystal structure is shown in Fig.…”

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confidence: 99%

Colossal Pressure-Induced Softening in Scandium Fluoride

et al. 2020

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The counterintuitive phenomenon of pressure-induced softening in materials is likely to be caused by the same dynamical behavior that produces negative thermal expansion. Through a combination of molecular dynamics simulation on an idealized model and neutron diffraction at variable temperature and pressure, we show the existence of extraordinary and unprecedented pressure-induced softening in the negative thermal expansion material scandium fluoride ScF 3. The pressure derivative of the bulk modulus B, B 0 ¼ ð∂B=∂PÞ P¼0 , reaches values as low as −220 AE 30 at 50 K, and is constant at −50 between 150 and 250 K.

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“…In addition, the Gruneisen equation can also be used to express the relationship between the CTE of a material and temperature [25]. This is expressed by the mode Gruneisen equation as:…”

Section: Thermal Expansion Model Of Compositesmentioning

confidence: 99%

Current Status of Research on the Modification of Thermal Properties of Epoxy Resin-Based Syntactic Foam Insulation Materials

Zhang

Dai

et al. 2021

Polymers

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As a lightweight and highly insulating composite material, epoxy resin syntactic foam is increasingly widely used for insulation filling in electrical equipment. To avoid core burning and cracking, which are prone to occur during the casting process, the epoxy resin-based syntactic foam insulation materials with high thermal conductivity and low coefficient of thermal expansion are required for composite insulation equipment. The review is divided into three sections concentrating on the two main aspects of modifying the thermal properties of syntactic foam. The mechanism and models, from the aspects of thermal conductivity and coefficient of thermal expansion, are presented in the first part. The second part aims to better understand the methods for modifying the thermal properties of syntactic foam by adding functional fillers, including the addition of thermally conductive particles, hollow glass microspheres, negative thermal expansion filler and fibers, etc. The third part concludes by describing the existing challenges in this research field and expanding the applicable areas of epoxy resin-based syntactic foam insulation materials, especially cross-arm composite insulation.

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First‐Principles Study of Sc_1−xTi_xF₃ (x ≤ 0.375): Negative Thermal Expansion, Phase Transition, and Compressibility

Cited by 20 publications

References 38 publications

First-principles study of phonon anharmonicity and negative thermal expansion in ScF3

First-principles study of phonon anharmonicity and negative thermal expansion in ScF3

Colossal Pressure-Induced Softening in Scandium Fluoride

Current Status of Research on the Modification of Thermal Properties of Epoxy Resin-Based Syntactic Foam Insulation Materials

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