Interplay between Phonons and Anisotropic Elasticity Drives Negative Thermal Expansion in PbTiO3
نویسندگان
چکیده
منابع مشابه
Acoustic phonons and negative thermal expansion in MOF-5.
The mechanism of negative thermal expansion (NTE) in MOF-5 has been studied using a rigid unit mode analysis of the phonons responsible for NTE. In addition to confirming the role of the previously proposed optic 'trampoline mode' mechanism [Lock et al., Dalton Trans., 2013, 42, 1933-2320], we have identified a new acoustic mode mechanism that makes a major contribution to the macroscopic NTE o...
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We report progress towards understanding how phonon anharmonicity contributes to negative thermal expansion (NTE). Some contribution to the NTE is from "quasiharmonic" behavior, where phonon frequencies decrease as a crystal expands. A second "anharmonic" effect from phonon-phonon interactions is sometimes calculated by perturbation theory, but sometimes the anharmonic effects are too large to ...
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The lattice thermal conductivity (κ) of hexagonal Ge2Sb2Te5 (h-GST) is studied via direct first-principles calculations. We find significant intrinsic anisotropy (κa/κc~2) of κ in bulk h-GST, with the dominant contribution to κ from optic phonons, ~75%. This is extremely unusual as the acoustic phonon modes are the majority heat carriers in typical semiconductors and insulators. The anisotropy ...
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Materials with zero/near zero thermal expansion coefficients are technologically important for applications in thermal management and engineering. To date, this class of materials can only be produced by chemical routes, either by changing chemical compositions or by composting materials with positive and negative thermal expansion. Here, we report for the first time a physical route to achieve...
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Introduction Many materials which we encounter in everyday life expand on heating. This fact of life is easily highlighted with a simple experiment that we are all familiar with and involves a metallic sphere passing through a metal ring. At room temperature, the sphere is of such a size that it can easily pass through the ring, but after the sphere is heated, it will have expanded with the res...
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ژورنال
عنوان ژورنال: Physical Review Letters
سال: 2018
ISSN: 0031-9007,1079-7114
DOI: 10.1103/physrevlett.121.255901