Temperature variation of the dielectric properties of bismuth germanate and bismuth germanium oxide

Abstract

The unclamped complex dielectric constant for bismuth germanium oxide (Bi12GeO20) and bismuth germanate [Bi4(GeO 4)3] has been determined at audio frequencies over the temperature range 6-325 K. For bismuth germanate, no dipolar impurities were observed. For bismuth germanium oxide, a strong dipolar impurity has been observed with an activation energy of 0.041 eV and a reciprocal frequency factor of 1.86×10-13 s. The strength of the relaxation is found to be correlated with the coloration of the sample. Possible origins of the relaxation are discussed. The results for the imaginary part of the dielectric constant were used to arrive at corrected values of the real part of the unclamped dielectric constant over the full range of temperatures. While absolute values are accurate to about 1.0%, the precision of the data is better than 0.1% relative to the room-temperature value.