scholarly journals Thermal Conductivity of BAs under Pressure

2021 ◽  
Author(s):  
Songrui Hou ◽  
Bo Sun ◽  
Fei Tian ◽  
Qingan Cai ◽  
Youming Xu ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Pressure Dependence ◽  
Acoustic Phonon ◽  
Density Functional ◽  
Phonon Scattering ◽  
Ambient Pressure ◽  
Functional Theory ◽  
Small Phase ◽  
Diamond Anvil ◽  
Scattering Rates

Abstract Boron arsenide (BAs) is an ultrahigh-thermal-conductivity material with special phonon-phonon scattering behaviors. At ambient pressure, the bunching of acoustic phonon branches in BAs is believed to result in a small phase space for three-phonon scattering. Density functional theory predicts that this acoustic phonon bunching effect is sensitive to pressure and leads to an unusual pressure dependence of thermal conductivity. To explore this physics, we measure the thermal conductivity of BAs from 0 to 25 GPa using time-domain thermoreflectance in a diamond anvil cell. We characterized two BAs samples with ambient thermal conductivities of 350 and 480 W m-1 K-1. Our experiments show that the thermal conductivity of both samples depends weakly on pressure from 0 to 25 GPa. We attribute the weak pressure dependence of the thermal conductivity of BAs to the weak pressure dependence of total phonon-phonon scattering rates. Our experimental results are consistent with DFT predictions that three-phonon scattering rates increase from 0 to 25 GPa, while four-phonon scattering rates decrease.

Physical properties of chalcopyrite-type Cu1−xAgxGaTe2 by first-principles study

2016 ◽  
Vol 30 (30) ◽  
pp. 1650373 ◽  
Author(s):  
Li Xue ◽  
Yi-Ming Ren ◽  
Zheng-Long Hu
Keyword(s):  
Thermal Conductivity ◽  
Elastic Constants ◽  
Density Functional ◽  
Lattice Thermal Conductivity ◽  
Lattice Parameter ◽  
Functional Theory ◽  
Lattice Volume ◽  
Te Material ◽  
Ag Substitution ◽  
Good Agreement

[Formula: see text] is a promising thermoelectric (TE) material for high temperature TE applications. This work systematically investigated the structural, elastic and thermodynamic properties of [Formula: see text] ([Formula: see text] = 0, 0.25, 0.5, 0.75 and 1) by density functional theory. The calculated lattice volume is expanded with the increase of Ag content, but this expansion is anisotropic. The lattice parameter along [Formula: see text]-axis is linear expansion, and along [Formula: see text]-axis is parabolic expansion, which is in good agreement with available experimental data. The phase stability of [Formula: see text] alloy is studied by analyzing the formation energy, cohesive energy and elastic constants. Shear modulus, Young’s modulus, sound velocities, Debye temperature and the minimum thermal conductivity are obtained from the calculated elastic constants. The results show that Ag substitution could reduce the lattice thermal conductivity, which is helpful for improving the TE properties of [Formula: see text].

scholarly journals A High-Pressure Investigation of the Synthetic Analogue of Chalcomenite, CuSeO3∙2H2O

Crystals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 643 ◽  
Author(s):  
Javier Gonzalez-Platas ◽  
Placida Rodriguez-Hernandez ◽  
Alfonso Muñoz ◽  
U. R. Rodríguez-Mendoza ◽  
Gwilherm Nénert ◽  
...  
Keyword(s):  
Phase Transition ◽  
Density Functional Theory ◽  
Raman Spectroscopy ◽  
Pressure Dependence ◽  
Density Functional ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
X Ray ◽  
Raman Modes

Synthetic chalcomenite-type cupric selenite CuSeO3∙2H2O has been studied at room temperature under compression up to pressures of 8 GPa by means of single-crystal X-ray diffraction, Raman spectroscopy, and density-functional theory. According to X-ray diffraction, the orthorhombic phase undergoes an isostructural phase transition at 4.0(5) GPa with the thermodynamic character being first-order. This conclusion is supported by Raman spectroscopy studies that have detected the phase transition at 4.5(2) GPa and by the first-principles computing simulations. The structure solution at different pressures has provided information on the change with pressure of unit–cell parameters as well as on the bond and polyhedral compressibility. A Birch–Murnaghan equation of state has been fitted to the unit–cell volume data. We found that chalcomenite is highly compressible with a bulk modulus of 42–49 GPa. The possible mechanism driving changes in the crystal structure is discussed, being the behavior of CuSeO3∙2H2O mainly dominated by the large compressibility of the coordination polyhedron of Cu. On top of that, an assignation of Raman modes is proposed based upon density-functional theory and the pressure dependence of Raman modes discussed. Finally, the pressure dependence of phonon frequencies experimentally determined is also reported.

scholarly journals Elastic Properties of Orthorhombic YBa2Cu3O7 under Pressure

Crystals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 497 ◽  
Author(s):  
Cai Chen ◽  
Lili Liu ◽  
Yufeng Wen ◽  
Youchang Jiang ◽  
Liwan Chen
Keyword(s):  
Thermal Conductivity ◽  
Debye Temperature ◽  
Elastic Constants ◽  
Density Functional ◽  
Elastic Anisotropy ◽  
Elastic Stability ◽  
Functional Theory ◽  
Conductivity Increase ◽  
Isotropic Pressure ◽  
The Density Functional Theory

The pressure dependence of the lattice and elastic constants of the orthorhombic YBa 2 Cu 3 O 7 are firstly investigated using the first principles calculations based on the density functional theory. The calculated lattice parameters at 0 GPa are in agreement with the available experimental data. By the elastic stability criteria under isotropic pressure, it is predicted that YBa 2 Cu 3 O 7 with and orthorhombic structure is mechanically stable under pressure up to 100 GPa. On the basis of the elastic constants, Pugh’s modulus ratio, Poisson’s ratio, elastic anisotropy, Debye temperature, and the minimum thermal conductivity of YBa 2 Cu 3 O 7 under pressure up to 100 GPa are further investigated. It is found that its ductility, Debye temperature, and minimum thermal conductivity increase with pressure.

scholarly journals The effect of ionic composition on acoustic phonon speeds in hybrid perovskites from Brillouin spectroscopy and density functional theory

2018 ◽  
Vol 6 (15) ◽  
pp. 3861-3868 ◽  
Author(s):  
Irina V. Kabakova ◽  
Ido Azuri ◽  
Zhuoying Chen ◽  
Pabitra K. Nayak ◽  
Henry J. Snaith ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Acoustic Phonon ◽  
Density Functional ◽  
Ionic Composition ◽  
Functional Theory ◽  
Brillouin Spectroscopy ◽  
The Impact

The impact of A and X site substitution on acoustic phonon speeds in hybrid perovskites with ABX3 stoichiometry is studied.

scholarly journals Ultralow and anisotropic thermal conductivity in semiconductor As2Se3

2018 ◽  
Vol 20 (3) ◽  
pp. 1809-1816 ◽  
Author(s):  
Robert L. González-Romero ◽  
Alex Antonelli ◽  
Anderson S. Chaves ◽  
Juan J. Meléndez
Keyword(s):  
Thermal Conductivity ◽  
Density Functional Theory ◽  
First Principles ◽  
Density Functional ◽  
Lattice Thermal Conductivity ◽  
Boltzmann Transport Equation ◽  
First Principles Calculations ◽  
Boltzmann Transport ◽  
Functional Theory ◽  
Anisotropic Thermal Conductivity

An ultralow lattice thermal conductivity of 0.14 W m−1 K−1 along the b⃑ axis of As2Se3 single crystals was obtained at 300 K by first-principles calculations involving density functional theory and the resolution of the Boltzmann transport equation.

Ultra low lattice thermal conductivity and high carrier mobility of monolayer SnS2and SnSe2: a first principles study

2017 ◽  
Vol 19 (31) ◽  
pp. 20677-20683 ◽  
Author(s):  
Aamir Shafique ◽  
Abdus Samad ◽  
Young-Han Shin
Keyword(s):  
Thermal Conductivity ◽  
Density Functional Theory ◽  
First Principles ◽  
Carrier Mobility ◽  
Density Functional ◽  
Lattice Thermal Conductivity ◽  
Functional Theory ◽  
First Principles Study ◽  
High Carrier Mobility ◽  
High Carrier

Using density functional theory, we systematically investigate the lattice thermal conductivity and carrier mobility of monolayer SnX2(X = S, Se).

Synthesis and thermoelectric properties of tantalum-doped ZrNiSn half-Heusler alloys

2014 ◽  
Vol 07 (03) ◽  
pp. 1450032 ◽  
Author(s):  
Degang Zhao ◽  
Min Zuo ◽  
Zhenqing Wang ◽  
Xinying Teng ◽  
Haoran Geng
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Acoustic Phonon ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Phonon Scattering ◽  
Heusler Alloys ◽  
Hot Press ◽  
Arc Melting ◽  
Hot Press Sintering

The Ta -doped ZrNiSn half-Heusler alloys, Zr 1-x Ta x NiSn , were synthesized by arc melting and hot-press sintering. Microstructure of Zr 1-x Ta x NiSn compounds were analyzed and the thermoelectric (TE) properties of Zr 1-x Ta x NiSn compounds were measured from room temperature to 823 K. The electrical conductivity increased with increasing Ta content. The Seebeck coefficient of Zr 1-x Ta x NiSn compounds was sharply decreased with increasing Ta content. The Hall mobility was proportional to T-1.5 above 673 K, indicating that the acoustic phonon scattering was predominant in the temperature range. The thermal conductivity was effectively depressed by introducing Ta substitution. The figure of merit of ZrNiSn compounds was improved due to the decreased thermal conductivity and increased electrical conductivity. The maximum ZT value of 0.60 was achieved for Zr 0.97 Ta 0.03 NiSn sample at 823 K.

scholarly journals Structural, Elastic, and Electronic Properties of Antiperovskite Chromium-Based Carbides ACCr3(A = Al and Ga)

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
D. F. Shao ◽  
W. J. Lu ◽  
S. Lin ◽  
P. Tong ◽  
Y. P. Sun
Keyword(s):  
Fermi Level ◽  
Density Functional ◽  
Ambient Pressure ◽  
Experimental Studies ◽  
Lattice Parameter ◽  
First Principles Calculation ◽  
Functional Theory ◽  
Multiple Band ◽  
A Site ◽  
Formation Energies

We theoretically investigated antiperovskite chromium-based carbides ACCr3through the first-principles calculation based on density functional theory (DFT). The structure optimization shows that the lattice parameter of ACCr3is basically proportional to the radius of A-site elements. The calculated formation energies show that AlCCr3and GaCCr3can be synthesized at ambient pressure and are stable with nonmagnetic ground states. Based on the calculation of elastic constants, some elastic, mechanical, and thermal parameters are derived and discussed. AlCCr3and GaCCr3show ductile natures and may have similar thermal properties. From the analysis of the electronic structures, it was found that there are electron and hole bands that cross the Fermi level for AlCCr3and GaCCr3, indicating multiple-band natures. The Fermi level locates at the vicinity of the density of states (DOSs) peak, which leads to a large DOS at Fermi level dominated by Cr-3d electrons. The band structures of AlCCr3and GaCCr3are very similar to those of the superconducting antiperovskite MgCNi3. The similarity may make AlCCr3and GaCCr3behave superconductively, which needs to be further investigated in theoretical and experimental studies.

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