PREPARATION OF UNIFORM SUBMICROMETER PARTICLES OF CALCIUM TITANATE AND LEAD NIOBATE BY REPLACEMENT REACTIONS

Uniform submicrometer particles or calcium titanium peroxo-hydroxide were prepared by adding calcium salts to the solution of peroxotitanium species chelated with nitrilotriacetic acid (NTA). Similarly, corresponding lead-niobium compound of [Pb]/[Nb] = 0.75 was obtained by introducing lead salts into the solution of chelated niobium complex with ethylenediaminetetraacetic acid (EDTA) at pH 3. Calcium ions in solutions containing a mixture of NTA-chelated Pb and NTA-chelated Nb complexes also caused the precipitation of lead niobium oxo-hydroxide of [Pb]/[Nb] = 1.5 at pH 9. The so-obtained precursor powders were converted on calcination to the corresponding composite oxides. The mechanisms of these reactions were suggested, based on the chemical, thermal, and X-rav diffraction analyses.