Dielectric Bodies in Metal Stannate‐Barium Titanate Binary Systems

Abstract

Ceramic and dielectric properties of bodies in the binary systems of barium titanate plus the stannates of magnesium, lead, bismuth, zinc, nickel, copper, cadmium, cobalt, manganese, and iron have been investigated. Bodies in the system tin oxide‐barium titanate also have been evaluated. Additions of tin oxide, lead stannate, cadmium stannate, zinc stannate, and copper stannate progressively decrease the Curie temperature of the body. Lead stannate bodies exhibit somewhat flatter peaks than the others and show much less variation of dielectric constant with temperature than do similar bodies prepared with the stannates of barium, calcium, or strontium. Additions of magnesium stannate, bismuth stannate, and nickel stannate greatly depress the Curie peak of barium titanate bodies. Bismuth stannate is particularly effective in producing bodies with very low temperature coefficient of dielectric constant. Bodies having dielectric constants of 4000 to 5000 (+25%, −50% from −60° to 85°C.) may be obtained from compositions containing about 15 mole % PbSnO3. Bodies having dielectric constants of 2000 to 2300 (+ 10%, −40% from −60° to 85°C.) may be obtained from compositions containing about 4 or 5 mole% of either MgSnO3or NiSnO3. Bodies having dielectric constants of 1000 to 1200 (−4% from −60° to 85°C.) may be obtained from compositions containing about 5 mole % Bi2(SnO3)3. Limited data indicate that the aging of various compositions apparently increases with level of dielectric constant. Non‐linearity with d.‐c. bias is greatest for high peak‐K bodies. Up to the limits investigated, additions of CaSnO3, PbSnO3, MgSn03, and Bi2 (SnO3)3 are absorbed in BaTiO3 bodies as solid‐solution‐type simple cubic structures with slightly expanded lattices.