Vitrified ceramic dielectric prodn. with high dielectric constant - from calcium, magnesium, barium and lanthanum titanates

摘要

The prodn. of a vitrified ceramic dielectric ontg. Ca, Mg and Bi titanates as described in the parent patent, is effected using a mixt. contg. or yielding 1-85 esp. 72 or 65 wt.% Ca titanate; 0.5-85 esp. 5 or 8% Mg titanate; 1-60% esp. 2 or 18 wt.% Bi titanate and 0.5-50 esp. 3 or 9 wt.% La titanate. The dielectric constant of the prod. is 20-50% higher than usual and the material gives more reliable capacitors. In an example, for compsns. contg. 65.6 (62.8)% CaTiO3, 8.3 (20.6)% Mg2TiO4, 17.8 (17.6)% Bi2(TiO3)3 and 8.3 (0)% La2(TiO3)3, fired at 1270 (1260) degrees C, the dielectric constant was 122(102), loss tangent 1.7 (1.1) x 10-4, insulation resistance 50 (14) x 106 Mohm, temp. coefft. -840 (-1070) x 10-6/degrees C and breakdown voltage 23 (18) kV/mm.