The pressure effects on the structural, elastic and thermodynamic properties of tantalum mononitride in WC-type phase (i.e. WC–TaN) are investigated by the first-principles plane wave pseudo-potential density functional theory method and the quasi-harmonic Debye model. The obtained equilibrium structure parameters and ground state properties are in excellent agreement with the experimental and other theoretical results. The calculations of the phonon dispersion curve and the density of phonon states verify that the WC–TaN is dynamically stable. A full elastic tensor and anisotropies behavior of the WC–TaN is also evaluated and discussed in the wide pressure range. The results show that WC–TaN is elastic anisotropy and mechanically stable up to 100 GPa, and the compression along c-axis direction is more difficult than along a-axis. The obtained superior mechanical properties show that WC–TaN is a promising candidate structure to be one of the ultra-incompressible and hard materials. Finally, by using the quasi-harmonic approximation model, we predicted the thermodynamic properties of WC–TaN under pressure and temperature. The heat capacity C_V, Debye temperature θ, the thermal expansion α and the Grüneisen constant γ are obtained successfully in the ranges of 0–100 GPa and 0–2000 K.

中文翻译：

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高压对单氮化钽的结构，弹性和热力学性质的影响

通过第一性原理平面波拟势密度泛函理论方法和准谐波德拜模型研究了压力对WC型相（即WC–TaN）中单氮化钽的结构，弹性和热力学性质的影响。所获得的平衡结构参数和基态性质与实验和其他理论结果非常吻合。声子色散曲线和声子态密度的计算证明了WC–TaN是动态稳定的。还在宽压力范围内评估和讨论了WC–TaN的全弹性张量和各向异性行为。结果表明，WC–TaN具有弹性各向异性，在高达100 GPa的压力下机械稳定，并且沿c方向的压缩轴方向大于沿着更难一个轴。获得的优异机械性能表明，WC-TaN是一种很有前途的候选结构，它将成为超不可压缩和坚硬的材料之一。最后，通过使用准谐波近似模型，我们预测了在压力和温度下WC–TaN的热力学性质。在0–100 GPa和0–2000 K的范围内成功获得了热容量C _V，德拜温度θ，热膨胀α和Grüneisen常数γ。