基于第一性原理的Ⅷ型Ba_(8)Ga_(16-x)Al_(x)Sn_(30)(x=0,6,16)笼合物结构稳定性及电子结构性质

Structural stability and electronic structural properties of type-Ⅷ Ba_(8)Ga_(16-x)Al_(x)Sn_(30)(x=0,6,16)clathrates from first-principles calculations

基于密度泛函的第一性原理从理论上探索Ba_(8)Ga_(16-x)Al_(x)Sn_(30)(x=0,6,16)笼合物的电子能带结构和结构稳定性。结果表明,Al置换Ga后笼合物的晶格常数增加,当Al部分置换Ga时笼合物结构稳定性增强;Ba_(8)Ga_(10)Al_(6)Sn_(30)笼合物由于费米能级附近能带较密集会表现出较好的电传输特性;在费米能级附近,Ba_(8)Al_(16)Sn_(30)具有较高的态密度,且态密度线更陡峭,这有利于提高材料的Seebeck系数,然而也可能引起材料结构的稳定性下降。这些结果为进一步研究Ba8Ga16Sn30笼合物提供较好的理论指导。

In this work,the structural stability and electronic structural properties of type-ⅧBa_(8)Ga_(16-x)Al_(x)Sn_(30)(x=0,6,16)clathrates are investigated by first-principle calculations based on density functional theory.The results show that when Ga is replaced by Al,the lattice parameter of the clathrate increases.The structural stability of the clathrate is enhanced when Ga is partially replaced by Al.Ba_(8)Ga_(10)Al_(6)Sn_(30) clathrate exhibits better electrical transmission characteristics due to the relatively dense energy band near the Fermi level.Near the Fermi energy level,Ba_(8)Al_(16)Sn_(30) has a high state density and a steep state density line,which is conducive to improving the Seebeck coefficient of the material,but may also cause the decrease of the stability of the material structure.These results provide a good theoretical guidance for further study of Ba8Ga16Sn30 clathrates.