Elastic, Piezoelectric, and Dielectric Constants of Bi12 GeO20

Abstract

In order to resolve conflicting published results concerning the values of the elastic, piezoelectric, and dielectric constants of Bi12GeO20, an exhaustive study of this material has been made. Over 45 samples of material grown by three independent sources were tested. The piezoelectric constant was determined using three different techniques. In addition, the first accurate measurements of the dielectric constant of Bi12GeO20 at microwave frequencies have been made. Recommended values of the material constants are as follows: c11E=1.28×1011 N/m2, c12E=0.305×1011 N/m2, c44E=0.255×1011 N/m2, e14 = 0.99 C/m2, and ε11S=34.2×10−11 F/m.