Measurement of the Elastic, Piezoelectric, and Dielectric Constants of Bi12GeO20.
Physical sciences research papers,
AIR FORCE CAMBRIDGE RESEARCH LABS L G HANSCOM FIELD MASS
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The low acoustic velocity of bismuth germanium oxide Bi12GeO20 has made it an attractive delay line material for achieving long time delays in short spaces. To resolve conflicting published results concerning the values of the elastic, piezoelectric, and dielectric constants of Bi12GeO20, an exhaustive study of the material was made. Over 45 samples of material grown by 3 independent sources were tested. The basic technique adopted for determining the elastic and piezoelectric coefficients involved the frequency measurement of acoustic resonances of thin plates. Since the largest discrepancy between two previous series of measurements was in the value of the piezoelectric constant, this coefficient was determined using three different methods. The first accurate determination of the dielectric constant of Bi12GeO20 at microwave 2 to 4 GHz frequencies was made by measuring the frequency of a low order TE electromagnetic mode of a disk resonator placed between two semi-infinite conducting planes. A listing of the computer program relating theory and experiment for this measurement is provided. Author
- Solid State Physics