Formation of La₂Ti₂O₇ crystals from amorphous La₂O₃-TiO₂ powders synthesized by the polymerized complex method

Amorphous La₂O-TiO₂ powders were synthesized by the polymerized complex (PC) method. The activation energies for crystallization and grain growth of La₂Ti₂O₇ from these precursors were determined from results of XRD and DTA and compared with those for La₂Ti₂O₇ precursors by the conventional solid-state reaction (SSR). Activation energy of grain growth of La ₂Ti₂O₇ in PC-sample was determined to be 7.1 kJ/mol while that of SSR sample was 14.8 kJ/mol. The energy required for the phase transformation from amorphous PC sample to layered perovskite was 432 kJ/mol, while the SSR sample did not show this transition below 900°C. It was clearly demonstrated that the La₂Ti₂O₇ crystals were formed at a lower temperature and they grew in size faster in the sample prepared by the PC method relative to the sample prepared by the SSR method. Mixing of elements in molecular level in PC preparation appeared responsible for these differences.