ALKOXIDE HYDROXIDE ROUTE FOR THE PREPARATION OF GAMMA-LIALO2-BASED CERAMICS

An alkoxide-hydroxide route has been developed to prepare Li4+xAl4-3xSi2xO8 (0 less-than-or-equal-to x less-than-or-equal-to 0.25) powders by taking into account fundamental aspects of the sol-gel process. This technique allows one to prepare powders which exhibit the beta-LiAlO2 type of structure after drying at 150-degrees-C. The beta- --> gamma-LiAlO2 topotactic transformation spreads over a large temperature range(746-839-degrees-C for x = 0.125) with no significant dilatometric and enthalpic change. Stoichiometric gamma-LiAlO2-based ceramics with a large variety of uniform microstructures are fabricated by a direct sintering of beta-LiAlO2 powders in the temperature range of 900-1100-degrees-C.