STUDIES OF MICROWAVE CERAMICS USING ADVANCED ANALYTICAL TECHNIQUES

Advanced analytical methods (low frequency spectroscopy, EXAFS, microw ave dielectric property measurements combined with electron microscopy and WDS microanalysis) for the characterization of stabilized La2/3Ti O3 and Ba6-xNd8+2/3xTi18O54 solid solutions are described. Low frequen cy dielectric spectroscopy showed that La2/3TiO3, stabilized with a sm all amount of LaAlO3 undergoes slight reduction when sintered in air. Using the same technique, the influence of firing temperature, firing atmosphere, and the content of LaAlO3 on the degree of reduction were investigated. EXAFS investigation of Bi- and Pb- doped Ba6-xNd8+2/3xTi 18S54 was used to determine the actual site of dopant atom incorporati on. Investigating the local structure of Bi3+ and Pb2+ incorporated in Ba6-xNd8+2/3xTi18O54, we showed that Bi3+ selectively enters one of t hree possible rhombic sites previously occupied by Nd3+, while Pb2+ se lectively enters one particular rhombic site previously shared by Ba2 and Nd3(+). The solid solubility limit of bismuth in Ba6-xNd8+2/3xTi1 8O54 was investigated mainly by observing the influence of Bi content on its microwave dielectric properties. The conclusions were additiona lly confirmed by other analytical methods (election microscopy, WDS).