Properties of barium-strontium titanate dielectrics

Abstract

The results on barium-strontium titanates are given for heat treatments, absorption, shrinkage, therm al expansion, dielectric constant (K) at -60 0 to 85 0 C, and also for Q, the recip rocal 01 the power factor, at 25 0 C for frequencies of 50 to 20,000 kc/s. A few measurements of K and Q were made at 3,000 me/s. Specimens matured (absorption less t han 0 .1 percent) at 1,250 0 to 1,430 0 C. K values ranged from 34, for BaO:4Ti02, to several thousand for specimens with compos itions on the BaTi03-SrTiOa join. Specimens having the composition BaO:5Ti02 were unique in that their temperat ure coefficient of K was practically zero. Q values ranged from 50 to 100 for test pieces containing over 40 percent of BaO , and from 400 to 10,000 for those with less than 40 percent of BaO. K values did not change appreciably with frequency. Linear thermal expansions between 25 0 and 700 0 C ranged from 0.6 to 0.84 percent. Many of these specimens could be used in radio equipment .