Dielectric behavior and cofiring with silver of monoclinic BiSbO ₄ ceramic

Pure monoclinic phase of BiSbO₄ ceramic was synthesized using the solid-state reaction method. BiSbO₄ ceramics can be well sintered between 960° and 1080°C. The dielectric constant of BiSbO₄ ceramic was about 20.1 and dielectric loss was about 0.055-2.5 × 10 ^-4 at 1 MHz. With the measured frequencies increasing from 100 to 900 kHz, the temperature coefficients of permittivity decreased from +224.1 to +95.9 ppm/°C. At the microwave range, the best microwave dielectric properties were obtained in the ceramic sintered at 1080°C/2 h with a permittivity of 19.3, a Q_f value of about 70 000 GHz, and a temperature coefficient of resonant frequency of -62 ppm/°C. Cofiring between BiSbO₄ ceramic and 20 wt% Ag was also investigated, and it was found that after cofiring at 900°C for 5 h only very little unknown phase containing a little amount of Ag was formed and most Ag was scattered in grain boundaries.