Barium titanate and barium-strontium titanate as nonlinear dielectrics

Abstract

An investigation was made of the nonlinear dielectric properties of barium titanate and barium strontium titanate with special emphasis on those properties that are pertinent to the design of nonlinear condensers for circuit applications. In order to carry the investigation to the highest possible field strengths, it was necessary to use samples in the form of thin sheets. The measuring circuit makes use of a General Radio type 916-A impedance bridge, which measures the high-frequency impedance of a simple condenser containing the dielectric in question. In addition to the high frequency measuring voltage a relatively large 'biasing' voltage is applied, which may be d-c for the first type of measurement or low frequency a-c for the second type of measurement. The impedance of the condenser is measured versus the d-c or instantaneous value of a a-c biasing voltage. For measurements of the second type, an oscilloscope is necessary as a bridge balance indicator. The dielectric constant versus field strength temperature and frequency was measured. Results are given in the figures included in this report.