Low temperature synthesis of ATiO3 (A: Mg, Ca, Sr, Ba) by using molten salt

Abstract

Alkaline earth metal titanates ATiO3 (A: Mg, Ca, Sr, Ba) were prepared from two types of layered potassium titanates [K2Ti2O 5 and K0.6Ti1.85O4 (hereafter, Lss)] by using alkaline earth metal molten salts [ACl2 + A(NO3) 2 (1:1)]. For A = Ca a single phase of perovskite-type compound was prepared at 600°C by using both starting compounds and the reaction temperature was lower than in 400°C that of the solid state reaction with TiO2 (anatase) and CaCO3. A single phase of perovskite-type SrTiO3 was obtained at 600 and 700°C for K 2Ti2O5 and Lss, respectively and these temperatures were much lower than that (1200°C) of the solid state reaction with TiO2 (anatase) and SrCO3. In the case of perovskite-type BaTiO3 a single phase of perovskite-type compound was prepared at 700°C by using both starting compounds and also this temperature was much lower than that (above 1300°C) of the solid state reaction with TiO2 (anatase) and BaCO3. Although neither K2Ti2O5 nor Lss could produce a single phase of ilmenite-type MgTiO3, it was prepared by the solid state reaction with TiO2 (anatase) and magnesium basic carbonate at 900°C. A single phase of ilmenite-type CdTiO3 was prepared from K 2Ti2O5 by using cadmium molten salts [CdCl 2 + Cd(NO3)2 (1:1)] at 500°C. By taking account of the fact that ilmenite-type CdTiO3 transforms to perovskite-type structure, this preparative method using layered potassium titanates with molten salts preferred to crystallize perovskite-type titanates at lower temperature rather than ilmenite-type ones. © 2013 The Ceramic Society of Japan.