第一性原理研究反Heusler合金 Ti2RuSn的Y位Rh掺杂效应

First-principles study on the Y-site Rh doping effects of the inverse Heusler alloy TiRuSn

本文基于第一性原理计算方法,通过对具有半金属性的反Heusler合金Ti2RuSn的Y位进行多d电子掺杂,来探究其掺杂前后的相关特性及掺杂机理,以便寻求半金属性更稳定的Heusler合金材料,为后续相关理论研究及实验提供一定参考.在掺杂过程中随着Rh元素掺杂浓度的增加,反Heusler合金Ti2RuSn的磁性呈线性增加,由未掺前的2μB增加到全掺时的3μB,同时其半金属性并未受到破坏且其带隙在逐渐变宽.在掺杂浓度为75%时,掺杂体的带隙宽度由未掺前的0.45 eV展宽到0.54 eV,同时费米面被调节到带隙中部靠上位置,这说明化合物Ti2Ru0.75Rh0.75Sn较未掺杂前具有相对稳定的半金属性.为分析掺杂体系的稳定性,我们计算了它们的相对形成能,结果表明,在掺杂浓度范围内,体系的形成能都为负值,并且掺杂浓度越高,其值越低.这说明反Heusler合金Ti2RuSn容易受到掺杂元素Rh的影响,并且大浓度的Rh掺杂可以有效地调节反Heusler合金Ti2RuSn的电子结构及能带结构,得到稳定性更好,使用性能及实用性更高的Heusler合金化合物.

The first-principles calculations within the DFT are performed to investigate effects of the more-d electrons doping on the Y-site of inverse Heusler compound Ti2RuSn. The results show that with the increase of the doping concentration, the magnetism of inverse Heusler alloy Ti2RuSn increases linearly from 2 μB to 3μB. Besides, the half-metallic property is not damaged and the band gap gradually widens. When the doping concentration is 75%, the width of the band gap is extended from 0.45 eV to 0.54 eV, and the Fermi level is adjusted to get closer to the middle of the band gap, indicating that the compound Ti2Ru0.75Rh0.75Sn has a relatively stable half-metallicity compared to the ideal bulk. In order to analyze the stability of the doping systems, we calculated their relative formation energies. The results showed that their formation energies are all negative, and the higher the doping concentration is, the lower the formation energy is. That is to say, the inverse Heusler alloy Ti2RuSn is susceptible to the influence of the doped element Rh, and its electronic structure and band structure can be effectively regulated by the high-concentration Rh doping, so as to obtain the Heusler compounds with more stable half-metallicity, better performance and higher practicability.