Effects of Crystal Structure on the Microwave Dielectric Properties of ABO 4 ( A  =  Ni , Mg , Zn and B  =  Mo , W ) Ceramics

The dependence of microwave dielectric properties on the crystal structure, bond character, and electronic characteristics of AMoO 4 and AWO 4 ( A = Ni , Mg , Zn ) ceramics was investigated. The dielectric constant ( K ) of specimens was principally affected by the dielectric polarizabilities, molar volume, and electronic oxide polarizabilities. MgMoO 4 and AWO 4 ( A = Ni , Mg , Zn ) display a single phase monoclinic wolframite structure, whereas ZnMoO 4 is a single phase triclinic wolframite structure. The quality factor ( Qf ) of AWO 4 was higher than that of AMoO 4 ( A = Mg , Zn ); these results were attributed to the packing fraction due to effective ionic size. The temperature coefficient of the resonant frequency ( TCF ) of the specimens was dependent on the cations' bond valence between the cation and oxygen ions. This suggests the ability to tailor ABO 4 microwave K , Qf , and TCF via ionic design rules.