The effects of solid-solution additives, their concentration, and the thermal processing schedule on the microstructure evolution and microwave properties of Ba2Ti9O20 were studied. The solubility of tin in Ba2Ti9O20 was higher than that of zirconium. Both elements facilitated the formation of phase-pure Ba2Ti9O20 resonators. Ba2Ti9O20 formed most easily with low dopant concentrations (0.82 mol%) (most impressively for ZrO2 substitutions). Extended heat treatment (16 h versus 6 h at a temperature of 1390°C) resulted in volatilization of the grain-boundary liquid phase, which leads to more-porous resonators that have correspondingly lower permittivities. Increasing the dopant concentration resulted in minor increases in the quality factor; doping with zirconium led to slightly higher values (a maximum of 13900 at a frequency of 3 GHz). Increasing the measurement temperature degraded the quality factor (most precipitously for BaTi4O9). The temperature coefficient decreased as the ZrO2 substitution increased but was largely unaffected by the SnO2 concentration. Excess TiO2 in a batch with no other dopants demonstrated degraded microwave properties.
|Original language||English (US)|
|Number of pages||5|
|Journal||Journal of the American Ceramic Society|
|State||Published - 1999|
All Science Journal Classification (ASJC) codes
- Ceramics and Composites
- Materials Chemistry