Effect of B-site ions on crystal structure evolution and microwave dielectric properties of scheelite-type CaW1-xMoxO4 (x = 0–0.12)

Herein, the influences of Mo 6+ substitution at the B-site on the sintering character, microstructures, and dielectric properties of scheelite-type CaW 1- x Mo x O 4 ( x  = 0–0.12) ceramics were studied in detail. The formation of scheelite solid solutions effectively reduced the sintering temperature of conventional CaWO4 ceramics from 1150 °C to 950 °C . Appropriate Mo substitution improved the compactness of the samples (relative density is 98.78 %), promoted grain growth, and consequently influenced their dielectric properties. At x = 0.08, the modified ceramics exhibited significantly improved dielectric properties compared to conventional CaWO 4 ceramics, with ε r ∼9.92 ± 0.05, Q ×  f ∼64848.33 ± 1459 GHz (@12.8 GHz), and τ f  ∼ −20.97 ± 1.91 ppm/°C. Furthermore, comprehensive analyses employing Piller-Van Loan (P-V-L) chemical bond theory, lattice vibration characterization analysis, and ionic polarizability evaluation demonstrated that the chemical stability of W-O bonds is the important factor governing the variations in dielectric properties of CaW 1-x Mo x O 4 ceramics. This study presents a promising candidate material for microwave device applications.