Correlations between the structural characteristics and enhanced microwave dielectric properties of V-modified Li3Mg2NbO6 ceramics

Novel low-temperature fired Li3Mg2Nb1-xVxO6 (x = 0.02 −0.08) microwave dielectric ceramics were synthetized by the partial substitution of V5+ ions on the Nb5+ sites. The effects of V5+ substitution on structure and microwave dielectric properties were investigated in detail. XRD patterns and Rietveld refinement demonstrated that all of the samples exhibited a single orthorhombic structure. The structural characteristics such as the polarizability, packing fraction and NbO6 octahedron distortion were determined to establish the correlations between the structure and the microwave dielectric characteristics. The ɛr values presented a tendency similar to that of the polarizability. The high Q×f values were mainly attributed to the effects of the grain sizes and density rather than the packing fraction. The variation in the τf values was attributed to NbO6 octahedron distortion. Notably, the Li3Mg2Nb1-xVxO6 (x = 0.02) ceramics sintered at 900 °C had outstanding microwave dielectric properties: εr= 16, Q×f= 131,000 GHz (9.63 GHz), and τf= − 26 ppm/°C, making these ceramics promising ultralow loss candidates for low temperature co-fired ceramics (LTCC) applications.