外压条件下TaN及Ta-Si-N结构相变的第一性原理研究
First-principles studies on phase transition of TaN and Ta-Si-N under extra pressure

利用基于第一性原理密度泛函理论的赝势平面波方法,对TaN、Ta-Si-N的B1型（NaCl）和B2型 （CsCl）复合结构在压力下的的力学常数、体积-能量关系、焓-压关系以及声子色散关系图进行了计算和研究，并分析了他们的相对稳定性。根据计算结果，推断在90―110 GPa左右压力时，Ta-N薄膜将会发生由B1型向B2型的相变，且材料脆性增加；当压力在190―200GPa的范围内，Ta-Si-N薄膜也将发生B1―>B2型的结构转变，由延展性材料压变为脆性材料。
The mechanical constants, volume energy curve, enthaly-pressure relation, phonon dispersion relations and relative stability of B1 and B2 types of TaN and Ta-Si-N films under pressures were calculated and studied using the plane wave pseudopotential method based on density functional theory(DFT). The results show that the phase transition of TaN film from B1 type to B2 type may occur in the pressure range of 90-110GPa and material would become more brittle; B1 type of Ta-Si-N film would transform into B2 type in 190-200GPa and it would be pressured into brittle material from ductile one.