Synthesis, gelation behaviour and evolution of oligomeric structure of BaTi double alkoxide

BaTi (BT) double alkoxides were synthesized by refluxing Ba and Ti methoxye thoxides. The gelation behaviours of the mixed alkoxides and BT double alko xide, and the evolution of BT double alkoxide structure were investigated. A remarkable increment in gelation time was found for the synthesized doubl e alkoxide system, compared with the mixed Ba and Ti alkoxide. In the case of the double alkoxides it was also observed that the gelation time was gre atly influenced by the refluxing time used during their synthesis. A shorte st gelation time was observed in the double alkoxides for refluxing times i n the range of 2-3 h, attributed to the evolution of their oligomeric struc ture during the refluxing period. The evolution can be suggested as a trans ition between non-crystalline and crystalline states, with the shortest gel ation time being observed near the crystalline state. The application of BT double alkoxides as precursors enabled a higher degree of homogeneity to b e achieved during the sol-gel transition, and the obtaining of the BaTiO3 c rystalline phase at lower temperatures (from 600 degrees C), compared with the mixed alkoxides (750 degrees C). (C) 2000 Elsevier Science B.V. All rig hts reserved.