PROPERTIES OF BARIUM‐MAGNESIUM TITANATE DIELECTRICS*

Abstract

A bstract Dielectrics having compositions in the system BaTiO 3‐ ‐4MgO:TiO 2 ‐TiO 2 were matured (<0.1% of absorption) at temperatures from 1275° to 1425°C. Data are given for dielectric constant, K , and the reciprocal of the power factor, Q , at 25°C. and frequencies of 50, 1000, 20,000 kc. per sec. and 3000 me. per sec.; also K at a frequency of 1 mc. per sec. and at various temperatures from —60° to 85°C. Values of K (1 mc. per sec. and 25°C.) ranged from 12 to 1550 and those of Q from 9 to 10,000. Values of K decreased and those of Q increased for several weeks after specimens were matured, when the content of BaO was greater than 30% and that of TiO 2 less than 50%. Partial restoration of the original values of K and Q resulted from Beating these specimens at various temperatures for brief periods. Linear thermal expansion (25° to 700°C.) ranged from 0.46 to 0.71%. A few specimens of barium‐strontium titan ate were tested for the effects of thermal history on the properties.