Ca ₃WO ₆: A novel microwave dielectric ceramic with complex perovskite structure

Present work introduces a novel Ca ₃WO ₆ microwave dielectric ceramic with a complex perovskite structure. The Ca ₃WO ₆ ceramic was prepared by solid state reaction method and can be well densified at above 1,260 °C for 2 h in air. All the XRD patterns can be fully indexed as a single-phase monoclinic structure (space group P2 ₁/n). The sharp Raman vibration mode at 810 cm ^-1 suggests the long range order in the Ca ₃WO ₆ structure. The best microwave dielectric properties can be obtained in ceramic sample sintered at 1,275 °C for 2 h with a permittivity ∼15.3, a Qf value ∼29,200 GHz and a TCF value about -30 ppm/°C. Applying the oxide additivity rule, the calculated permittivity agrees well with the measured value. This kind of ceramic might have some potential value for microwave application for its good microwave dielectric behavior. The (Ca _1/2W _1/2) complex cations holding the site of Ti ⁴⁺ in perovskite structure would introduce many new systems in complex perovskite compounds in the future.