The Dielectric Properties of Barium Titanate at Low Temperatures

The complex dielectric constatn of ceramic barium titanate has been measured as a function of temperature from 300°K down to 2.8°K. The large value of the slope of the real part of the dielectric constant, $K^{\prime }$, versus temperature curve in the 4°K region previously reported by Wul was observed in the measurements described here, and a large hump in the $tan\delta$ versus temperature curve was observed at low temperatures. Measurements were also made on barium titanate diluted with 15 percent and 30 percent strontium titanate. The dilution in both cases gave large slopes in the $K^{\prime }$ versus temperature curve at low temperatures. The measurements were made largely at 500 kilocycles per second.