Properties of barium-magnesium titanate dielectrics

D ielectrics having compositions in the system BaTi03-4 MgO:TiOz-Ti02 were matured (less th an 0.1 % of absorption) at 1,275 0 to 1,425 0 C. Data a re given for the dielectric constant K at a frequency of 1 mc/s and variou temperat ures from -60 0 to + 85 0 C, and fo r Q, t he reciprocal of t he power factor, at 25° C and frequencies of 50, 1,000, and 20,000 kc/s and 3,000 mc/s.Values of K (1 mc/s and 25 0 C) ranged from 12 to 1,550 and t hose of Q from 9 to 10,000.Values of K decreased, and those of Q increased for several weeks aftcr I'lpecimens were matured, when the content of BaO was greater than 30 percent and that of Ti02 less than 50 perccnt.P artial restoration of the original values of K and Q rcs ul tcd from heating these speci mcns at various temperatures for brief pcriods.Linear thermal expansion (25 0 to 700 0 C) ranged from 0.46 to 0.71 percent.A few specimen of bari umstrontium t itanate were tested for the effects of thermal history on the properties,