Acoustical method for the determination of the elastic and piezoelectric constants of crystals of classes 6mm and 4mm

An acoustical method is proposed for the determination of the elastic and piezoelectric constants of crystals of classes 6mm and 4mm. The method is based on the technique developed for orthorhombic crystals of class mm2 and described in the previous paper [9]. Only three samples are required for the determination of all elastic and piezoelectric constants of crystals belonging to the two symmetry classes of interest; for the crystals of class 6mm, only two samples are necessary. The proposed method can be used only when the signs of the piezoelectric constants are known beforehand. Knowing the sign of electrostriction for the crystals under study, the relative signs of the piezoelectric constants can be uniquely determined in accordance with the data reported earlier [10]. This approach allows one to extend the method used in the previous paper [9] to crystals of classes 6mm and 4mm.