Reaction mechanism on the formation of (Sr, Ba)TiO₃ and Ba(Zr, Ti)O₃ at near room temperature by using A(OH)₂•8H₂O (A = Sr, Ba) and BO₂•nH₂O gel (B = Zr, Ti, Zr_0.45Ti_0.55)

Recently, our group synthesized perovskite-type oxide ABO₃ (A = Sr, Ba; B = Ti, Zr) with high crystallinity simply by leaving a powder mixture of A(OH)₂•nH₂O and BO₂ hydrous gel at room temperature to 323 K for 3–10 days. In this study, perovskite solid solution (Ba, Sr)TiO₃ and Ba(Zr, Ti)O₃ were synthesized to investigate the reaction mechanism in this synthesis method in detail. The perovskite solid solution (Ba, Sr)TiO₃ was obtained by using barium hydroxide, strontium hydroxide and TiO₂ hydrous gel as the staring materials. On the other hand, in the case of using barium hydroxide and the mixture of TiO₂ hydrous gel and ZrO₂ hydrous gel as the starting materials, a mixed phase of BaTiO₃ and BaZrO₃ was obtained. B-site-substituted perovskite solid solution Ba(Zr_0.45Ti_0.55)O₃ was obtained by using barium hydroxide and (Zr_0.45Ti_0.55)O₂ hydrous gel as the starting materials. From the above, it was clarified that in this synthetic method, the Sr and Ba ions diffuse into the water part of hydrous gel and then slowly react with Ti(OH)₄ to form a perovskite lattice.