Characterization of ferroelectric and superconducting ceramics prepared from precursor carbonates

The advantages of a new semi-wet method for the synthesis of (Ba, Ca)TiO₃ and YBa₂Cu₃O_{7 − y} powders from precursor carbonates are described. The precursor carbonates are prepared using chemical coprecipitation technique under controlled pH conditions to ensure uniform distribution of Ba⁺²/Ca⁺² and Y⁺³/Ba⁺² ions. It is shown that the powders synthesized by this route possess better chemical homogeneity as compared to those obtained by the conventional ceramic technique involving calcination of a mixture of BaCO₃, CaCO₃, TiO₂ and Y₂O₃, BaCO₃, CuO powders. The behaviour of the ferroelectric (Ba, Ca)TiO₃ and the superconducting YBa₂Cu₃O_{7 − y} ceramics prepared from powders obtained by our method are found to be markedly different from those known for the conventionally prepared ceramics.