New low-dielectric-loss NiZrNb2O8 ceramics for microwave application.

New low-loss NiZrNb 2 O 8 microwave dielectric ceramics were synthesized via conventional mixed oxide route. The morphology, crystal structure and microwave dielectric properties were investigated. It exhibited a monoclinic wolframite crystal structure, with the space group of P2/c ( C 2 h 4 ) . The lattice energy was carried out to evaluate the structural stability and sintering characteristics. Two kinds of grain shapes in dense samples, with similar elements ratios, were observed. Variations in the dielectric constant (ε r ) were analyzed by relative density and porosity-corrected polarizability. The quality factor (Q × ƒ) was correlated with packing fraction and grain growth. The temperature coefficient of resonant (τ ƒ ) was depended on the dielectric constant. The typical microwave dielectric properties of NiZrNb 2 O 8 were ε r = 23.77, Q × ƒ = 40280 GHz, τ ƒ = −27.5 ppm/°C, sintered at 1200 °C. [ABSTRACT FROM AUTHOR]