HfN结构相变及热力学性质的第一性原理研究

Study on first principles of phase transition and thermodynamic properties of HfN

采用基于密度泛函理论的第一性原理方法对HfN的结构稳定性、力学性质、声子色散关系和热力学性质进行了研究.通过计算焓压关系、声子谱和弹性性质,得知常压下NaCl结构比CsCl结构更稳定.HfN由NaCl结构到CsCl结构的相变发生在177~200 GPa之间.同时对NaCl-HfN的热力学性质进行了分析,结果表明:一定温度下,等体热容、热膨胀系数和格乃森参数均随温度增加而增大.

Structural stability, mechanical properties,phonon dispersion relations and thermodynamic properties of HfN was investigated by using the first-principle method based on the density-functional theory （DFF）. Enthalpy-pressure relation, phonon spectrum and e- lastic properties show that NaC1 structure is more stable compared with the CsC1 structure at atmospheric pressure. The phase transition of HfN to CsC1 structure from NaC1 structure occurred between 177 GPa and 200 GPa. The thermodynamic properties of NaC1-HfN was analysed. The results show that heat capacity, thermal expansion coefficient and Genaisen parameters increase with increasing the tem- perature under certain pressure.