PHOSPHOR-DOPED BATIO3 - MICROSTRUCTURE DEVELOPMENT AND DIELECTRIC-PROPERTIES

The phosphor cation retards BaTiO3 formation during the first reaction stage, and favours Ba2TiO4 formation. As a consequence, the end of th e reaction is only accomplished at 1150 degrees C. The average particl e size of the synthesized powder, after attrition milling was < 1.0 mu m. Isopressed bars were sintered from 1200-1400 degrees C. Dilatometr ic measurements showed the existence of two sintering mechanisms; thes e were confirmed by means of isothermal sintering experiments. Microst ructural development at low sintering temperature differs from that co rresponding to higher ones. Very high permittivity values were measure d in the 1325-1350 degrees C sintered samples. This anomalous dielectr ic behaviour is associated with the presence of phosphor.