Li 6 NiNb 2 O 9 Compound with Rock-Salt Crystal Structure and Its Microwave Dielectric Properties

A ternary compound of Li6NiNb2O9 with a rock-salt structure was prepared by the conventional mixed oxide route, and after the ceramic preparation processes, its microwave dielectric properties were investigated. Ceramics with a single phase and a rock-salt crystal structure can be obtained under our optimized sintering conditions, and a disordered rock-salt structure for Li6NiNb2O9 compound can be confirmed by the Rietveld method. Relatively dense microstructures can be obtained under the sintering conditions of 1080°C/2.0 h, with microwave dielectric properties of e = 13.5, Q × f = 20,600 GHz (9.4 GHz) and τf = −33.9 ppm/°C. Although decomposition of such phase occurred when high sintering temperature was applied (> 1100°C), the density and microwave dielectric properties of the ceramics showed anomalous increases.