EFFECTS OF HEATING RATE ON SINTERING OF ALKOXIDE-DERIVED BATI5O11 POWDER

The effects of heating rate on the sintering of BaTi5O11 ceramics from an alkoxide-derived powder were investigated, and the microwave properties were measured. Density and the crystalline phase of the sintered bodies varied with heating rate. Density increased with an increase in heating rate up to 30-degrees-C/min and decreased at one exceeding 30-degrees-C/min. BaTi5O11 ceramics with > 99% theoretical density were obtained by sintering at 1120-degrees-C for 48 h with a heating rate at 30-degrees-C/min. The sintering with a heating rate at 100-degrees-C/min resulted in a decomposition of BaTi5O11 to Ba2Ti9O20 and rutile that hindered sintering. The dielectric constant epsilon(r) and Q volume, neither sensitive to microstructure or the crystalline phase, were 42 and ca. 6100 at 9.7 GHz, respectively. The temperature coefficient of resonant frequency tau(f) was 39.3 ppm/degrees-C at 7 GHz.