First-principles Study of Microscopic Origin of Piezoelectric Effect in α-Quartz

Abstract

Using a first-principles approach based on the density-functional theory, the piezoelectric properties of α-quartz are calculated. The computation is based on local-density approximation (LDA) and the density-functional perturbation theory (DFPT), directly yielding appropriate piezoelectric stress coefficients. The calculated results are in agreement with the experimental results. The internal piezoelectric coefficients e11,int and e14,int is decomposed into each ion and SiO4 tetrehedron in the primitive cell, respectively. In ionic decomposition, the ions most responsible for piezoelectric effects are Si14+, O22-, and O32-. In tetrahedral decomposition, the tetrahedra centered by Si24+ and Si34+ exhibit a higher piezoelectric coefficient than the tetrahedron centered by Si14+. The reason for these phenomena has been interpreted to be the difference between the geometric orientations of these two kinds of tetrahedra in α-quartz with respect to strain tensors.