Microwave and Infrared Dielectric Response of Temperature Stable (1− x ) BaMoO 4 – x TiO 2 Composite Ceramics

The (1− x ) BaMoO 4 – x TiO 2 ( x = 0.0, 0.2, 0.3, 0.338, 0.4, 0.5, 0.66) ceramics were synthesized by the conventional mixed‐oxide process. The sintering behaviors, phase composition, chemical compatibility with silver, and microwave dielectric properties of pure (1− x ) BaMoO 4 – x TiO 2 ceramics and 0.662 BaMoO 4 –0.338 TiO 2 ceramic with H 3 BO 3 – CuO addition were studied. Infrared reflectivity spectra of (1− x ) BaMoO 4 – x TiO 2 (0.2 ≤ x ≤ 0.4) composites were measured in the range of 50–4500 cm −1 at room temperature. X ‐ray diffraction analysis reveals that scheelite BaMoO 4 and rutile TiO 2 phase coexist with each other at 1275°C and both of them do not react with silver ( Ag ) at 850°C. When the mole fraction of TiO 2 ( x value) is 0.4, a temperature stable microwave dielectric material is obtained, with ε r = 13.8, Q × f = 40 500 GHz ( f = 8.02 G), and τ f = −6.13 ppm/°C. Complex dielectric spectra gained from the infrared spectra were extrapolated down to microwave range, and they were in good agreement with the measured microwave permittivity and dielectric losses. With 5 wt% H 3 BO 3 and 1 wt% CuO addition, the 0.662 BaMoO 4 –0.338 TiO 2 ceramics can be sintered well below 900°C, and possess good microwave dielectric properties with ε r = 14, Q × f = 48 360 GHz, and τ f = +13.9 ppm/°C.