Correlations between structure and microwave dielectric properties of Co doped MgMoO4 ceramics

Abstract Mg1-xCoxMoO4 (x = 0.01–0.15) ceramics were prepared by traditional solid-state methods. The phase composition, crystalline structure, micromorphology, and microwave dielectric properties of Mg1-xCoxMoO4 ceramics were comprehensively studied. Mg1-xCoxMoO4 ceramics present monoclinic wolframite structures from x = 0.01 to x = 0.15 with Co occupying the Mg-site. With the addition of Co2+, er of Mg1-xCoxMoO4 ceramics increase. Q × f is maximal at 5 mol% Co2+ content. The Mg0.95Co0.05MoO4 ceramic exhibits an optimal microwave dielectric property: er = 7, Q × f = 59247 GHz, τf = −68 ppm/°C. The Q × f values increase by 20% compared with the pure MgMoO4 ceramics (∼49149 GHz). Doping Co2+ effectively promotes the densification of ceramics and increases er and Q × f. However, when the Co content exceeds 5 mol%, the decreased packing fraction and disorder distribution of ions contribute to the increase in dielectric losses. The correlations between Co2+ substitution and wolframite structure have been discussed by Raman spectroscopy, FT-IR spectroscopy and Rietveld refinement.