高压下新型MAX相M_(2)SeC(M=Zr,Hf)的密度泛函理论研究  

Density Generalized Function Theory Study on New MAX Phase M_(2)SeC(M=Zr,Hf)under High Pressure

作　　者：何鑫 田辉 王健 陈万蕾 魏兆旋 刘金程 齐东丽[2] 沈龙海[2] HE Xin;TIAN Hui;WANG Jian;CHEN Wanlei;WEI Zhaoxuan;LIU Jincheng;QI Dongli;SHEN Longhai(School of Materials Science and Engineering,Shenyang Ligong University,Shenyang 110159,Liaoning,China;School of Science,Shenyang Ligong University,Shenyang 110159,Liaoning,China)

机构地区：[1]沈阳理工大学材料科学与工程学院,辽宁沈阳110159 [2]沈阳理工大学理学院,辽宁沈阳110159

出　　处：《高压物理学报》2023年第4期11-23,共13页Chinese Journal of High Pressure Physics

基　　金：国家自然科学基金(12274304);沈阳理工大学2022年引进高层次人才科研支持经费(1010147001132,1010147001137)。

摘　　要：基于密度泛函理论的第一性原理,研究了压力对新型MAX相Zr_(2)SeC和Hf_(2)SeC晶体结构、弹性、电子和热力学性质的影响。弹性常数和声子计算表明,两种化合物在0~40 GPa压力范围内具有稳定结构。与大多数MAX相不同,Zr_(2)SeC和Hf_(2)SeC沿a轴方向比沿c轴方向更容易被压缩,外部压力对Zr_(2)SeC晶体结构的影响比Hf_(2)SeC更显著。电子结构计算表明,Zr_(2)SeC和Hf_(2)SeC具有金属性质,压力的升高降低了Zr_(2)SeC和Hf_(2)SeC在费米能级处的电子态密度,因此提高了Zr_(2)SeC和Hf_(2)SeC的稳定性。此外,弹性模量、泊松比和各向异性指数等均随着压力的升高而增大。在0~40 GPa压力范围内,相同压力下Hf_(2)SeC的弹性模量大于Zr_(2)SeC,表明高压下Hf_(2)Se具有比Zr_(2)SeC更强的抗断裂和抗变形能力。热力学性质计算表明,Zr_(2)SeC和Hf_(2)SeC在0~40 GPa压力范围内具有较高的熔化温度。The effects of pressure on the crystal structure,elasticity,electronic and thermodynamic properties of the new MAX phases Zr_(2)SeC and Hf_(2)SeC were investigated by employing the first principle of density generalized function theory.Elastic constants and phonon calculations show that both compounds have stable structure in the pressure range of 0–40 GPa.Unlike most MAX phases,Zr_(2)SeC and Hf_(2)SeC are more easily compressed along the a-axis than along the c-axis,and the effect of external pressure on the crystal structure of Zr_(2)SeC is more significant than Hf_(2)SeC.Electronic structure calculations show that Zr_(2)SeC and Hf_(2)SeC have metallic properties,and the electronic density of states at the Fermi energy level decrease gradually with increasing pressure,thus improving the stability of Zr_(2)SeC and Hf_(2)SeC.In addition,the elastic modulus,the Poisson’s ratio and the anisotropy index show an enhancement with increasing pressure.In the pressure range of 0–40 GPa,the elastic modulus of Hf_(2)SeC is greater than that of Zr_(2)SeC at the same pressure,indicating that Hf_(2)SeC has stronger resistance to fracture and deformation than Zr_(2)SeC at high pressure.Thermodynamic property calculations show that Zr_(2)SeC and Hf_(2)SeC have higher melting temperatures in the pressure range of 0–40 GPa.

关 键 词：M_(2)SeC 高压 第一性原理 晶体结构 电子结构 

分 类 号：O521.2[理学—高压高温物理] O469[理学—物理]