NMR-STUDY OF THE SOL-GEL PREPARATION STEPS OF A CRYSTALLIZED LITAO3 POWDER

Samples with a composition close to LiTaO3 were prepared by solid state reactions from Li2CO3 and Ta2O5 powders and by a sol-gel method using alkoxides of lithium and tantalum. The successive steps of the LiTaO3 preparation process were followed by 1H- and 7Li-NMR spectroscopy, showing the formation of LiTa(OC2H5)6 in both ethanol and hexane, the xerogel evolution vs. the heat treatment and the various crystallization steps. Furthermore, the 7Li vq quadropolar splitting is shown to be dependent on the stoichiometry of the samples, i.e. on the Li:Ta atomic ratio. © 1990.