稀土La掺杂Mg2Si的几何结构、弹性性能和电子结构的第一性原理研究EI北大核心CSCD

采用密度泛函理论(DFT)的第一性原理平面波赝势方法对稀土元素镧(La)掺杂Mg2Si的几何结构、弹性性能和电子结构进行计算与分析。首先,结合形成焓、Born力学稳定性以及差分电荷密度的结果可知,掺杂稀土元素La之后,形成的Mg8Si4La和Mg8Si3La均不能稳定存在,La掺杂的Mg2Si优先占据体系Mg原子的位置;其次,晶体的体模量(B),剪切模量(G),杨氏模量(E),泊松比(ν),以及各向异性系数(A)的计算结果表明本征Mg2Si为脆性相,而Mg7Si4La为韧性相,掺杂La可以提高Mg2Si的延展性;最后,态密度、Mulliken布居数和电荷差分密度的计算结果表明掺杂稀土镧后费米面向高能级区域偏离,进入导带,提高了Mg2Si的导电性。

First principles study on geometry structure,elastic property and electronic structure of La-doped Mg2Si

The geometrical structure, elastic properties and electronic structure of Mg2Si doped with lanthanum(La) were calculated and analyzed by using the first-principles plane wave pseudopotential method of density functional theory. Firstly, combined with the results of the formation of erbium and Born mechanical stability, it can be seen that Mg8Si4La and Mg8Si3La do not exist stably after doping with rare earth element La. La-doped Mg2Si preferentially occupies the position of the system Mg atom;Secondly, the bulk modulus(B), the shear modulus(G), Young’s modulus(E), Poisson’s ratio(ν), and anisotropy coefficient(A) of the crystal were calculated that the intrinsic Mg2Si is a brittle phase, while Mg7Si4La is a ductile phase. The doping of La can improve the ductility of Mg2Si. Finally, the calculation of density of states, Mulliken population and charge differential density show that Fermi surface is deviated from the high-energy region after doping with rare earth, and enters the conduction band, which improves the conductivity of Mg2Si.