Y掺杂SrAl₂Si₂的电子结构与光学性质的第一性原理研究

【摘要】 文章采用基于密度泛函理论的第一性原理方法研究掺杂Y的Sr_1-xY_xAl₂Si₂（x=0,0.25,0.5和0.75）的晶体结构、电子性质和光学性质。研究发现掺杂Y的SrAl₂Si₂晶体结构发生了明显的压缩,Sr_0.5Y_0.5Al₂Si₂发生了相变,由三方晶系转变为单斜晶系。此外,能带结构的计算表明,SrAl₂Si₂是一种半金属,在导带和价带之间有很小的重叠。掺杂Y原子后,SrAl₂Si₂从半金属向金属转变,并且随着掺杂浓度从x=0.25,0.5到0.75,其金属性逐渐增强,这与态密度（DOS）的计算结果一致。这些结果表明,通过提高Y的掺杂浓度,SrAl₂Si₂基合金的热电性能很可能得到进一步的改善。最后,计算并分析了掺杂Y的Sr_1-xY_xAl₂Si₂（x=0,0.25,0.5和0.75）晶体的介电函数、能量损失谱和反射谱,得出Sr_1-xY_xAl₂Si₂是一种前景较好的介电材料,并且在20-30 eV能量范围内是良好的紫外透光材料。更多还原

【Abstract】 The First-Principles methods are used to study the structural, electronic and optical properties of the Y-doped Sr_1-xY_xAl₂Si₂（x=0, 0.25, 0.5 and 0.75）. Indeed, the structure was compressed evidently for Y-doped SrAl₂Si₂, and a structural transition was observed from trigonal to monoclinic configuration for Sr_0.5Y_0.5Al₂Si₂. Besides, the structure calculations revealed that SrAl₂Si₂ undergo semimetal to metal-like transition and the metallic characteristics was enhanced with increasing Y content from x=0.25, 0.5 to 0.75,which is consistent with the density of states（DOS）. Finally, the dielectric function, absorption spectrum, energy-loss spectrum and reflectivity were calculated and analyzed for Y-doped SrAl₂Si₂ crystals, which shows that it is a promising dielectric material and UVtransparent material around the range（20-30 eV）.更多还原