New temperature stable (Nd1−xLax)1.02Nb0.988O4 microwave dielectric ceramics

Abstract

(Nd1−xLax)1.02Nb0.988O4 ceramics with enhanced microwave dielectric properties were prepared via conventional solid-state reaction route. The effects of La3+ ions substitution for Nd3+ ions on the microwave dielectric properties of the NdNbO4 ceramics were investigated. Microscopic analysis showed that the specimens presented single NdNbO4 phase in the range of x=0.0–0.05, with a further increase of the amount of La3+ ions, LaNb5O14 phase appeared in the system. The variation tendency of dielectric constant was in accordance with the relative density. The Q×f value and τƒ value were correlated to packing fraction and bond strength, respectively. A near zero τƒ value can be obtained by carefully adjusting the substitution of La3+ content. At 1250°C, the (Nd1−xLax)1.02Nb0.988O4 ceramics with x=0.05 possesses excellent microwave dielectric properties: εr=21.52, Q׃=45,600GHz (at 7.512GHz) and τƒ=0ppm/°C.