The starting powder crystal phase effects on the microstructural development and electrical properties of (Ba,Bi,Nb)-doped TiO2 ceramics were studied using transmission electron microscopy (TEM), energy dispersion spectrometry (EDS), and X-ray diffractometry (XRD). It was observed that the amount of the second phase in the sample depends on calcination and sintering temperature. For the powder calcined at 1000 °C, which was rutile and contained a small amount of Ba2Ti9O20 and Bi2Ti4O11 second phases before sintering, the amounts of Ba+2 and Bi+3 that dissolved in the TiO 2 matrix during sintering were lower than those for the powders calcined at 700 °C (pure anatase). Because higher Ba+2 and Bi+3 amounts dissolved in the rutile grains during sintering, more Ba+2 and Bi+3 diffused from the matrix toward the grain boundary during cooling, which results in the formation of higher amounts of the second phase. The amounts of Ba+2 and Bi+3 that segregated in the grain boundary areas increased with increasing sintering temperature and decreased with increasing calcination temperature, which led to the samples calcined at lower temperatures and sintered at higher temperatures having a higher surface state density and a higher nonlinear exponent.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)