过渡金属掺杂TaN硬质涂层的力学性能和电子结构的第一性原理研究

First-principles study of mechanical properties and electronic structure of transition metal doped TaN hard coating

通过第一性原理计算,研究过渡金属(transition metal,TM)元素掺杂氮化钽(Ta7TMN8,TM=Ti、V、Cr、Y、Zr和Hf)的结构稳定性、力学性能和电子结构。根据对结构和稳定性的计算结果可知,所有的掺杂化合物均能量稳定,Ta7TiN8在能量上比其他掺杂化合物更有利;Y、Zr和Hf的掺入使得TaN晶格和体积膨胀,而Ti、V和Cr则相反。通过对力学性能的计算可知,Ti和V的掺入对TaN的剪切模量、弹性模量和理论硬度有较明显的提升,掺Cr对TaN的体积模量有一定的提升,但是会大幅降低理论硬度。基于Ta7TMN8总态密度和分态密度计算结果,费米能级附近存在态密度,表明所有化合物都具有金属性质,由于Ti-3d、V-3d和Cr-3d轨道在费米能级上的贡献比其他TM原子大得多,使得Ta7TiN8、Ta7VN8和Ta7CrN8具有更高的金属性。

The stability,mechanical properties,and electronic structure of transition metal(TM,TM=Ti,V,Cr,Y,Zr,and Hf)elements doped tantalum nitride(Ta7TMN8)were investigated by first-principles calculations.According to the calculation results of structure and stability,all the doped compounds are stable,and Ta7TiN8 is energetically more favorable than others.The doping of Y,Zr,and Hf can cause lattice and volume expansion of TaN,while Ti,V,and Cr play an opposite role.The calculated mechanical properties reveal that the addition of Ti and V can significantly improve the shear modulus,elastic modulus,and theoretical hardness of TaN,while doping Cr can only increase the volume modulus but significantly decrease the theoretical hardness.Based on the calculation results of the total and partial density of states of Ta7TMN8,the density of states at the Fermi level indicates that all compounds exhibit metallic nature.The contribution of Ti-3d,V-3d,and Cr-3d orbitals at the Fermi level is quite more than other TM atoms,leading to a more metallic character of Ta7TiN8,Ta7VN8,and Ta7CrN8.