Low-temperature sintering and microwave dielectric properties of TiO ₂-based LTCC materials

Temperature stable high-K LTCC material was prepared. The influence of fabrication process on the crystalline phases, microstructures and microwave dielectric properties of TiO ₂-Bi ₂O ₃-CuO ceramics were investigated. The crystalline phases and microstructures of TiO ₂-Bi ₂O ₃-CuO ceramics were investigated by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy. It was found that rutile TiO ₂ phase and Bi ₂Ti ₄O ₁₁ phase co-existed in the TiO ₂-Bi ₂O ₃-CuO ceramics. Separate TiO ₂ grains and Bi ₂Ti ₄O ₁₁ grains distributed uniformly in the ceramic matrix. The composition 0.92TiO ₂-0.08Bi ₂Ti ₄O ₁₁ with 2 wt% CuO addition that was sintered at 900 °C for 2 h showed high dielectric constant (ε _r ∼ 81), high quality factor (Q × f ∼ 3,500 GHz) and near zero temperature coefficient of resonant frequency (τ _f ∼ -5.1 ppm/°C), meanwhile the compatibility test showed that it could co-fire with silver electrode. The processing-microstructure-property interrelationship was also studied.