Sintering behavior, microwave dielectric properties and thermally stimulated depolarization current behavior of B2O3-doped CoTiNb2O8 ceramics

Abstract

Low-fired B2O3-doped CoTiNb2O8 (CTN) microwave dielectric ceramics were synthesized via the conventional solid-state reaction method. The effects of B2O3 on the sintering behavior, phase composition, crystal defects and microwave dielectric properties of CTN ceramics were studied systematically. The B2O3 additive could effectively lower the sintering temperature from 1250 to 1000 °C. Single tetragonal rutile phase was found for all samples tested. Room-temperature microwave dielectric properties at high frequency and temperature-dependent dielectric properties at low frequency were both studied. It was found that B2O3 could induce obvious dielectric relaxation which was largely linked to the oxygen vacancy ( $$V_{\text{O}}^{\bullet \bullet}$$ ). Also, newly formed defect dipole ( $$2Ti_{\text{Ti}}^{\prime } - V_{\text{O}}^{ \bullet \bullet}$$ ) was detected by thermally stimulated depolarization current measurement. These two kinds of defects were both responsible for the dielectric loss of CTN ceramics. When the amount of B2O3 addition was 3 wt%, CTN ceramics sintered at 1000 °C possessed the optimum microwave dielectric properties with a er of 63.4, a high Q × f of 18,793 GHz, and a τf of 80.48 ppm/°C, and was a promising candidate for low-temperature cofired ceramic (LTCC) applications.