Properties of calcium-barium titanate dielectrics

摘要

Dielectrics having compositions in the system 3CaO:TiO2-BaTiO3-TiO2 were matured (less than 0.1 percent absorption) at 1260° to 1500°C. Data are given for the compositions, heat treatments, absorption, shrinkage, and for K, the dielectric constant, and Q, the reciprocal of the power factor at 25°C and frequencies of 50, 1000, and 20,000 kc/s, and at 3,000 mc/s when K is not greater than 50. Values of K were also determined at 1 mc/s and various temperatures from -60° to +85°C. At 25°C and 1 mc/s, K ranged from 34 to 2670 and Q from 27 to 10,000. Lowest values of Q were associated with specimens of high baria content. The values of K decreased and those of Q increased for several weeks after the dielectrics. Were matured when the percentage of titania was less than 50 and that of baria greater than about 30. Linear thermal expansion (25° to 700°C) ranged from 0.65 to 0.87 percent. The specimens of composition 3CaO:TiO2 disintegrated after a few weeks when exposed to room conditions, and all the dielectrics containing less than 50 percent of titania and greater than about 30 percent of calcia deteriorated greatly in Q value after storage for a year.