第一性原理研究碳化铬的电子结构、硬度和德拜温度

First-Principles Calculations Study on the Electronic Structures, Hardness and Debye Temperatures of Chromium Carbides

摘要:

采用基于第一性原理的密度泛函理论，计算了3种碳化铬的晶格常数、电子结构、弹性模量、理论硬度和德拜温度等。结果表明，Cr3C2, Cr7C3 和Cr23C6的化学键均为共价键、离子键和金属键组成的混合键；Cr3C2的热力学和力学稳定性均最高；Cr3C2, Cr7C3和Cr23C6的理论硬度值分别为20.9, 18.3和13.2 GPa，这与近期的实验研究结果十分相近。此外，本研究预测了3种碳化铬的徳拜温度。

Abstract:

The structures, electronic properties, elasticity, theoretic hardness, and Debye temperatures of chromium carbides, Cr3C2, Cr7C3 and Cr23C6 were calculated by the density functional theory of first-principles. The results show that the deviation of equilibrium lattice parameters from the experimental data is small. The bond in these compounds is the mixture of covalent, ionic and metallic bonding. The most stable phase belongs to Cr3C2; the values of theoretic hardness of Cr3C2, Cr7C3 and Cr23C6 are 20.9, 18.3 and 13.2 GPa, respectively, which are in good agreement with recent experimental results. Besides, the Debye temperatures of chromium carbides were predicted.