Abstract
The ordered non-stoichiometric V8C7 can form in the VCy carbides by the disorder–order phase transformation. The intrusion of ordered carbon vacancies can affect their stability, mechanical, thermal and electronic properties. The relatively thermodynamic stability and mechanical properties at high temperature for the ordered stoichiometric VC and non-stoichiometric V8C7 are investigated in this paper by first-principle calculations combined with the quasi-harmonic approximation. The difference between the properties of VC and V8C7 can be obtained. We find that the V8C7 is thermodynamic more stable than VC, but has weaker elastic heat resistance than VC. Moreover, the minimum thermal conductivity of VC is a little larger than V8C7 and a simple way is proposed to characterize the anisotropy of lattice thermal conductivity based on the Cahill’s model.
Highlights
By comparing the simulated XRD of VC and V8C7 with the experimental results of V8C7 and VC1−x, we find our simulated results are in agreement with the experimental results[9,10]
We provide a simpler way to characterize the anisotropy of lattice thermal conductivity
The relatively thermodynamic stability, mechanical properties at high temperature and minimum lattice thermal conductivity of VC and ordered V8C7 are investigated by first-principle calculations combined with the quasi-harmonic approximation
Summary
Correspondence and requests for materials should be addressed to J.F. One is the difference for relatively thermodynamic stability and mechanical properties for the ordered stoichiometric VC and non-stoichiometric V8C7 at high temperature are obtained and compared with the theoretical and experimental results. The other one is a simple way is proposed to characterize the anisotropy of lattice thermal conductivity based on the Cahill’s model
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