Abstract: A process for producing a high density ceramic of perovskite represented by the formula:ABO.sub.

Abstract: Aqueous titanium tetrachloride solution and aqueous zirconium nitrate solution of components except zirconium, for forming lead zirconate-tinatate in which part of the lead is substituted for any of the lanthanide elements are mixed, and the mixture is hydrolyzed to form sol. This sol is cleaned, dried, and calcined at 1100.degree. C. to form modified powder. The compounds of the remaining component of lead zirconate-titanate, such as TiO.sub.2 powder, PbO powder and Sm.sub.2 O.sub.3 powder, are mixed with the modified powder, and the resultant mixture is calcined at 750.degree. C. for 1 hour to produce the lead zirconate-titanate.

Abstract: Aqueous titanium tetrachloride solution, i.e., one component (X) for forming multi-component ceramic compound, and a suitable amount of zirconium oxynitrate, i.e., another component (Y) are mixed. Hydroxide coprecipitate of Ti.sup.4+ and Zr.sup.4+ containing the components is formed from the mixture solution. The coprecipitate is cleaned, dried, then calcined, for example, at 1100.degree. C., thus producing powder containing 0.32-micron particles. This powder is mixed with TiO.sub.2 and PbO, in a suitable amount to be added to the other component (Y) of the multi-component ceramic compound. The resultant mixture is calcined, for example, at 740.degree. for 1 hour, into fine powder containing 0.32-micron particles. The calcined powder is then press-molded, for example, under the pressure of 1 ton/cm.sup.2, then calcined, for example, at 1220.degree. C. for 1 hour, thereby forming multi-component ceramics.

Abstract: A process for producing a powder material of perovskite or its solid solution represented by the formula:ABO.sub.3wherein A is one or more metal elements coordinated with 12 oxygen atoms, and B is one or more metal elements coordinated with 6 oxygen atoms, which comprises contacting an aqueous or alcohol solution of either component A or component B with a precipitating solution to form precipitates, then adding an aqueous or alcohol solution of the other component to form precipitates, and drying the precipitates, followed by calcining at a temperature of from 400.degree. to 1200.degree. C.