SYNTHESIS OF CALCIUM TITANATE POWDERS BY THE SOL-GEL PROCESS

Crystalline, phase-pure, submicrometer-sized calcium titanates have be en produced by a sol-gel method at low temperatures. Chemical reaction between calcium acetate and titanium(IV) isopropoxide leads to the fo rmation of optically transparent homogeneous calcium titanate gels. Af ter suitable drying and calcination treatments, the calcium titanate g els are converted to calcium titanate powders. CaTiO3, Ca3Ti2O7, and C a4Ti3O10 can be synthesized by this way as very sinter-active material s. The rate of densification during the sintering of compacts increase s as Ca3Ti2O7 < Ca4Ti3O10 < CaTiO3. The phases CaTi2O5 and CaTi4O9 can be formed as intermediates during the thermal degradation of the corr esponding gel precursors at temperatures below 700-degrees-C. They are metastable and decompose to CaTiO3 and rutile during the further ther mal treatment. The calcium titanate gels and the titanate powders were characterized by DTA, TG, XRD, SEM, B.E.T. measurements and chemical analysis.