Si_3N_4晶体的压电性能第一性原理研究  

First-principles Study of Piezoelectricity of Si_3N_4 Crystal

作　　者：曾一明[1] 郑燕青[1] 忻隽[1] 孔海宽[1] 陈辉[1] 涂小牛[1] 施尔畏[1] 

机构地区：[1]中国科学院上海硅酸盐研究所,上海201800

出　　处：《无机材料学报》2011年第2期180-184,共5页Journal of Inorganic Materials

基　　金：国家自然科学基金(50772121);中国科学院知识创新工程重要方向项目(KGCX-2-YW-206)~~

摘　　要：Si3N4是一种具有多种优越物化性能的多功能材料.采用基于密度泛函理论(DFT)的第一性原理计算对Si3N4的高低温相(β、α)进行了对比研究.对于α相,计算得晶格常数a=0.7678nm、c=0.5566nm,弹性刚度系数c11=4.232×1011N/m2、c33=4.615×1011N/m2,压电应变常量d33=0.402pC/N;而对于β相,a=0.7536nm、c=0.2874nm,弹性刚度系数c11=4.241×1011N/m2、c33=5.599×1011N/m2,压电应变常量则几乎为零.分析表明Si3N4的α、β两相均为高硬高强材料,这与其结构由四面体组成的网络架构有关.而Si3N4高低温相的压电性能都很差,特别是β相的压电系数几乎为零,这与其结构的对称性有关,高温相结构的对称性更高,形变引起的离子位移响应抵消更多.Si3N4 is a popular material with many excellent physicochemical properties.This present work make a comparative study on its low and high temperature phases（α-and β-Si3N4） by first-principles calculation based on density functional theory（DFT）.As for α phase,the calculated lattice parameters are a=0.7678nm,c=0.5566nm;elasticstiffness coefficients are c11=4.232×1011N/m2,c33=4.615×1011N/m2;piezoelectric strain coefficients are d33=0.402pC/N.While for β phase,they are a =0.7536nm,c = 0.2874nm,c11=4.241×1011N/m2,c33=5.599×1011N/m2 and the piezoelectric strain coefficients are nearly zero.The analysis shows that both α and β phases are high strength and high hardness,relating to their network structures of tetrahedron.The piezoelectricity is poor,especially for β-Si3N4.This can be attributed to the structural symmetry,higher symmetry and lower piezoelectricity.

关 键 词：SI3N4 压电性能 第一性原理 晶体结构 

分 类 号：TQ174[化学工程—陶瓷工业]