Piezoelectricity in quartz analogues^*

Abstract
The piezoelectricity of the crystal family containing quartz, its homeotypic crystals like AlAsO_4, berlinite (AlPO₄), FePO₄, GaAsO_4, GaPO_4, and the quartz-isotypic phase of GeO₂ is considered on a structural basis. The connection between the tetrahedral tilting angle and the strength of the piezoelectric coefficients can be explained with the help of a bondadditivity model. This model allows very precise calculations of the relative temperature dependencies of the piezoelectric d₁₁-coefficients. Beside the great similarity of the alpha phases, there are remarkable differences between the cristobalite phases of quartz and the cristobalite like phases of the MXO₄ homeotyps. The symmetries of the later allow also the piezoelectric effect.