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Debye model
About: Debye model is a research topic. Over the lifetime, 7462 publications have been published within this topic receiving 133987 citations.
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TL;DR: In this article, the Debye model was used to investigate the phonon scattering mechanisms in double-filled skutterudites, where two types of guest atoms (barium and rare-earth elements) were inserted into the voids of skutteruds to introduce additional phonon point defect scattering from the extra mass fluctuation at the void site.
Abstract: We use the Debye model to investigate the phonon scattering mechanisms in BaxREyCo4Sb12 double-filled skutterudites Filling two types of guest atoms (barium and rare-earth elements) into the voids of skutterudite introduces additional phonon point defect scattering from the extra mass fluctuation at the void site, and additional phonon resonant scattering by the fillers with different vibrational frequencies, leading to significant reduction in the lattice thermal conductivity
38 citations
TL;DR: In this article, a unified approach to states of matter (solid, liquid and gas) and describe the thermodynamics of the pressure-temperature phase diagram in terms of phonon excitations is introduced.
38 citations
TL;DR: In this article, first-principle calculations have been performed to investigate the structural phase transition, electronic, elastic, thermodynamical and optical properties of III-Sb compounds under hydrostatic pressure up to their first order transitions pressure (Zinc Blende to Rock Salt).
38 citations
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TL;DR: In this paper, the authors employed density functional theory calculations to investigate the mechanical behavior, bonding nature and defect processes of the new ordered MAX phase Mo2ScAlC2, and verified the mechanical stability of the compound with its single crystal elastic constants.
Abstract: In the present study we employed density functional theory calculations to investigate the mechanical behavior, bonding nature and defect processes of the new ordered MAX phase Mo2ScAlC2. The mechanical stability of the compound is verified with its single crystal elastic constants. The new phase Mo2ScAlC2 is anticipated to be prone to shear along the crystallographic b and c axes, when a rational force is applied to the crystallographic a axis. The compressibility along the direction under uniaxial stress is expected to be easier in Mo2ScAlC2. Additionally, the volume deformation should be easier in Mo2ScAlC2 than in the isostructural Mo2TiAlC2. Mo2ScAlC2 is predicted to behave in a brittle manner. Due to its higher Debye temperature, Mo2ScAlC2 is expected to be thermally more conductive than Mo2TiAlC2. The cross-slip pinning procedure should be significantly easier in Mo2ScAlC2 as compared to Mo2TiAlC2. The new ordered MAX phase Mo2ScAlC2 has a mixed character of strong covalent and metallic bonding with limited ionic nature. Both Mo-C and Mo-Al bonds are expected to be more covalent in Mo2ScAlC2 than those of Mo2TiAlC2. the level of covalency of Sc-C bond is somewhat low compared to a similar bond Ti-C in Mo2TiAlC2. Due to its reduced hardness, Mo2ScAlC2 should be softer and more easily machinable compared to Mo2TiAlC2. Fermi surface topology of the new compound is formed mainly due to the low-dispersive Mo 4d-like bands. The intrinsic defect processes reveal that the level of radiation tolerance in Mo2ScAlC2 is not as high as in other MAX phases such as Ti3AlC2.
38 citations
TL;DR: In this article, a quasi-harmonic Debye model combined with the first-principle theory was used to investigate the thermodynamic properties of different phases under high temperature and high pressure.
Abstract: First-principles calculations of the crystal structures (wurtzite (WZ) and rocksalt (RS)) and phase transition of AlN have been carried out with the plane-wave pseudopotential density functional theory (DFT) method. The calculated values (for crystal structures) are in agreement with available experimental value and other calculated data. Through the quasi-harmonic Debye model combined with the first-principles theory, the thermodynamic properties of different phases under high temperature and high pressure are investigated. The phase transition from WZ structure to RS structure occurs at the pressure of 15.0 GPa, which agrees well with experimental value. The evaluated equilibrium volume using this model agrees with the values obtained from ab intio and from experiment. The temperature and pressure dependence of quantities such as the equation of state (EOS), the isothermal bulk modulus, the heat capacity, and the thermal expansion are successfully obtained.
38 citations