RELATIONSHIP BETWEEN THE STRUCTURES AND T HE REACTION ACTIVITY FOR HYDROTHERMAL SYNTHESIS OF MZRO(3) (M=BA, SR, CA)

For hydrothermal synthesis of MZrO(3)(M = Ba, Sr, Ca), the synthetic r egularities and hydrothermal conditions were investigated, and the rea ction process was analyzed on the basis of the structures and properti es of ZrO2 . xH(2)O gelate and MZrO(3) (M = Ba, Sr, Ca). We proposed t hat the structure unit formed in the reaction process, in which alkali -earth ion combined with [Zr-4((OH)(8)(H2O)(16)](8+) ion. When the str ucture unit continually grew, the reactive activation energy increased with the decreasing of M(2+)(M = Ba, Sr, Ca) ionic radius, because th e incorporation of a smaller A-ion in the perovskite-type structure is accompanied by rotation of the ZrO6 octahedra.