MICROSTRUCTURE DEVELOPMENT OF Bi4Ti3O12 AND BaBi4Ti4O15 CERAMICS PREPARED BY MECHANOCHEMICAL SYNTHESIS

Abstract

Scveral bismuth-layered crystal structure and their properties have been investigated- in detail. However, a lot of aspects of the preparation and properties of barium bismuth titanate unexplored, whereas being promising candidate for memory applications. In present work barium-bismuth titanate (BaBi4Ti4O15-BBT) was prepared from stoichiometric, quantities of barium titanate and bisrnuth titanate obtained via mechanochemical synthesis. Barium titanate (BaTi3O12:-BT) has been synthesised from michture of BaO and Tio2 and bismuth titanate (Bi4Ti3O12-BIT) was prepared starting frorn Bi2O3 and TiO2 commercially available. Mechanochemical synthesis was performed in air atmosphere in , planetary ball mill, for BT during 60 min and for BIT during 360 min. Milling condition were: zirconium oxide jars and zirconium oxide balls, ball-to-powder weight ration 20:1 and determined basic disc and disc with jars rotation speed. The powder mixture of BT and BIT was homogenized for 30 min and after that sintered at 1100"C for 4h. Separatly, BIT was sintered at 1000 C for 12h, in both cases without pre-calcination step and by conventional sintering technique. The Fig. I. shows the phase formation and crystal structure of BIT, BT and mixture of this powders. Pattern of BBT powder sintered at 1100.c for 4h was analysed by XRD analysis revealing the existence of tetragonal phase (Fig. 2.). The morphology of obtained powders was examined by SEM and TEM method (Fig. 3. and Fig. 4.). It can be conclude that pattern of BIT consists of nanoparticles which size is less than 20 nm. Mixture of BIT and BT consists of agglomerates of varying size and morphology which size is about 250 nm. The microstructure development of BIT and BBT ceramics was followed by SEM. From Fig 5. and Fig. 6. it can be observed that BIT consists of plate-like grains but in the case of BBT beside plate-like grains exist and spheric grains, also' It is evident addition leads to the change in the microstructure development.