I型和VIII型Sr填充Si基、Ge基、Sn基笼合物电子结构的第一性原理研究

First Principle Calculation of Structural and Electronical Properties for Type Ⅰ and Type Ⅷ Sr-filled Si-Ge-Sn-based Clathrates

第一性原理是根据原子核和电子互相作用的原理及其基本运动规律,运用量子力学原理,从具体要求出发经过一些近似处理后直接求解薛定谔方程的算法。本文采用第一性计算原理计算Ⅰ-型和Ⅷ-型Sr填充Si基、Ge基、Sn基笼合物的结构和性质,研究不同基团对笼合物结构与电传输特性的影响。结果表明:Sr_8Ga_(16)Si_(30)、Sr_8Ga_(16)Ge_(30)、Sr_8Ga_(16)Sn_(30)都是间接带隙半导体,Sr_8Ga_(16)Sn_(30)的带隙最小且体模量最大,Sr_8Ga_(16)Sn_(30)带边结构的不对称性说明Sr_8Ga_(16)Sn_(30)的热电性能性能可能优于Sr_8Ga_(16)Si_(30)、Sr_8Ga_(16)Ge_(30),而引起材料结构性质差别主要为框架原子Sn、Ge、Si原子电子分布作用的结果。

First principle is an algorithm of using the principle of quantum mechanics to solve the schrodinger equation,which is according to the principle and the basic motion of interaction between atomic nucleus and electron.In this work,the structural and electronic properties of Type-Ⅰ and Type-Ⅷ Sr-filled Si-Ge-Sn-based clathrates have been investigated by fist principle calculation,and the effect of different atomic groups on the clathrate structure and electrical transport properties have been researched.The results suggested that Sr_8Ga_(16)Si_(30),Sr_8Ga_(16) Ge_(30) and Sr_8Ga_(16) Sn_(30) are all belongs to indirect-gap semiconductors materials,and Sr_8Ga_(16) Sn_(30) shows the smallest band gap and possesses the largest bulk modulus among them.The worse symmetry of band edge structure for Sr_8Ga_(16)Sn_(30) indicated the higher performance than Sr_8Ga_(16)Si_(30) and Sr_8Ga_(16)Ge_(30) and the main reason for the differences between Sr_8Ga_(16)Si_(30),Sr_8Ga_(16)Ge_(30) and Sr_8Ga_(16)Sn_(30) can be attributed to the different electronic distribution of Sn,Ge and Si atomic.