Stability, chemical bonding behavior, elastic properties and lattice thermal conductivity of molybdenum and tungsten borides under hydrostatic pressure

2016 ◽  
Vol 42 (2) ◽  
pp. 2117-2132 ◽  
Author(s):  
XiaoYu Chong ◽  
YeHua Jiang ◽  
Rong Zhou ◽  
Jing Feng
Keyword(s):  
Thermal Conductivity ◽  
Hydrostatic Pressure ◽  
Elastic Properties ◽  
Chemical Bonding ◽  
Lattice Thermal Conductivity ◽  
Tungsten Borides ◽  
And Tungsten

Elastic properties and lattice thermal conductivity of amorphous Ge2Sb2Te5 and GeTe thin films

2021 ◽  
Vol 129 (13) ◽  
pp. 135102
Author(s):  
M. Baloi ◽  
D. Wamwangi ◽  
B. A. Mathe ◽  
R. M. Erasmus ◽  
D. G. Billing ◽  
...  
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Elastic Properties ◽  
Lattice Thermal Conductivity

scholarly journals First-Principles Study of Structure, Elastic Properties, and Thermal Conductivity of Monolayer Calcium Hydrobromide

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Si-Hua Li ◽  
Cui-E Hu ◽  
Xiao-Lu Wang ◽  
Yan Cheng
Keyword(s):  
Thermal Conductivity ◽  
Elastic Properties ◽  
First Principles ◽  
Lattice Thermal Conductivity ◽  
Mechanical Stability ◽  
Iterative Solution ◽  
Mean Free Path ◽  
Hydrogen Atmosphere ◽  
Theoretical Studies ◽  
Boltzmann Transport

In recent years, some laboratories have been able to prepare calcium hydrobromide (CaHBr) by melting hydride and anhydrous bromide or metal and bromide in a hydrogen atmosphere at 900°C and have studied some of its properties. But there are few theoretical studies, especially the theoretical studies of monolayer CaHBr. We use the first-principles method to calculate the structure, elastic properties, and lattice thermal conductivity of the monolayer CaHBr based on the Boltzmann transport equation. We obtain a stable crystal structure by the optimization of monolayer CaHBr. By calculating the elastic constant of monolayer CaHBr, its mechanical stability is proved, and the elastic limit of monolayer CaHBr is obtained by biaxial tensile strain on monolayer CaHBr. And the corresponding phonon spectra show no imaginary frequency, indicating the dynamic stability of the monolayer CaHBr. By the ShengBTE code, we calculate the lattice thermal conductivity of the monolayer CaHBr, the iterative solution of BTE and RTA at 300 K–1200 K is obtained, and the lattice thermal conductivity at room temperature is κ ι BTE = 2.469   W / m ⋅ K and κ ι RTA = 2.201   W / m ⋅ K , respectively. It can be seen that the lattice thermal conductivity of monolayer CaHBr is low. And by analyzing the phonon spectrum, the scattering rate, and the mean free path of the phonons, the lattice thermal conductivity of monolayer CaHBr mainly depends on the acoustic modes. We hope this study can provide theoretical guidance for the experiments and practical application of monolayer CaHBr.

The Hydrostatic Pressure Effect on Elastic Properties of B2-Phase Single Crystals Ti50Ni48Fe2and Ti50Ni45Fe5Alloys

1995 ◽  
Vol 05 (C8) ◽  
pp. C8-729-C8-734
Author(s):  
A.I. Lotkov ◽  
V.P. Lapshin ◽  
V.A. Goncharova ◽  
H.V Chernysheva ◽  
V.N. Grishkov ◽  
...  
Keyword(s):  
Hydrostatic Pressure ◽  
Single Crystals ◽  
Elastic Properties ◽  
Pressure Effect ◽  
B2 Phase

Lattice Thermal Conductivity Modelling of a Diatomic Nanoscale Material

2020 ◽  
Vol 10 (5) ◽  
pp. 602-609
Author(s):  
Adil H. Awad
Keyword(s):  
Thermal Conductivity ◽  
Lattice Thermal Conductivity ◽  
Phonon Scattering ◽  
Correction Term ◽  
Nanoscale Material ◽  
New Approach ◽  
Two Samples ◽  
Conductivity Modelling ◽  
Callaway Model

Introduction: A new approach for expressing the lattice thermal conductivity of diatomic nanoscale materials is developed. Methods: The lattice thermal conductivity of two samples of GaAs nanobeam at 4-100K is calculated on the basis of monatomic dispersion relation. Phonons are scattered by nanobeam boundaries, point defects and other phonons via normal and Umklapp processes. Methods: A comparative study of the results of the present analysis and those obtained using Callaway formula is performed. We clearly demonstrate the importance of the utilised scattering mechanisms in lattice thermal conductivity by addressing the separate role of the phonon scattering relaxation rate. The formulas derived from the correction term are also presented, and their difference from Callaway model is evident. Furthermore their percentage contribution is sufficiently small to be neglected in calculating lattice thermal conductivity. Conclusion: Our model is successfully used to correlate the predicted lattice thermal conductivity with that of the experimental observation.

scholarly journals Local ferroelectric polarization switching driven by nanoscale distortions in thermoelectric $${\text {Sn}}_{0.7}{\text {Ge}}_{0.3}{\text {Te}}$$

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Aastha Vasdev ◽  
Moinak Dutta ◽  
Shivam Mishra ◽  
Veerpal Kaur ◽  
Harleen Kaur ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Lattice Thermal Conductivity ◽  
Direct Evidence ◽  
Temperature Dependent ◽  
Force Microscopy ◽  
Ferroelectric Domains ◽  
Pdf Analysis ◽  
Ferroelectric Transition Temperature

AbstractA remarkable decrease in the lattice thermal conductivity and enhancement of thermoelectric figure of merit were recently observed in rock-salt cubic SnTe, when doped with germanium (Ge). Primarily, based on theoretical analysis, the decrease in lattice thermal conductivity was attributed to local ferroelectric fluctuations induced softening of the optical phonons which may strongly scatter the heat carrying acoustic phonons. Although the previous structural analysis indicated that the local ferroelectric transition temperature would be near room temperature in $${\text {Sn}}_{0.7}{\text {Ge}}_{0.3}{\text {Te}}$$ Sn 0.7 Ge 0.3 Te , a direct evidence of local ferroelectricity remained elusive. Here we report a direct evidence of local nanoscale ferroelectric domains and their switching in $${\text {Sn}}_{0.7}{\text {Ge}}_{0.3}{\text {Te}}$$ Sn 0.7 Ge 0.3 Te using piezoeresponse force microscopy(PFM) and switching spectroscopy over a range of temperatures near the room temperature. From temperature dependent (250–300 K) synchrotron X-ray pair distribution function (PDF) analysis, we show the presence of local off-centering distortion of Ge along the rhombohedral direction in global cubic $${\text {Sn}}_{0.7}{\text {Ge}}_{0.3}{\text {Te}}$$ Sn 0.7 Ge 0.3 Te . The length scale of the $${\text {Ge}}^{2+}$$ Ge 2 + off-centering is 0.25–0.10 Å near the room temperatures (250–300 K). This local emphatic behaviour of cation is the cause for the observed local ferroelectric instability, thereby low lattice thermal conductivity in $${\text {Sn}}_{0.7}{\text {Ge}}_{0.3}{\text {Te}}$$ Sn 0.7 Ge 0.3 Te .

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