Correlation of crystal structure and microwave dielectric properties of Zn1−xNixZrNb2O8 (0 ≤ x ≤ 0.1) ceramics

Wolframite-structured Zn 1−x Ni x ZrNb 2 O 8 (0 ≤ x ≤ 0.1) ceramics were synthesized by the conventional solid-state method. The effects of Ni 2+ substitution on sintering characteristic, crystal structure, and microwave dielectric properties of ZnZrNb 2 O 8 samples were systematically studied. The relationship among bond ionicity, lattice energy, thermal expansion coefficient and microwave dielectric properties was also investigated by the complex chemical bond theory. The dielectric constant of Zn 1−x Ni x ZrNb 2 O 8 ceramics sintered at 1150 °C slightly decreases from 28.06 to 26.35 with the increasing Ni 2+ content, which can be explained by the variation of bond ionicity and polarizability. Raman scattering spectra also reveal that the increase in Ni 2+ content leads to the shift in all the vibration modes and the variation of ionicity in Nb O bond. The Q · f values increases from about 40,000 to 60,000 GHz with the increasing Ni 2+ content, which can be explained by the variation of lattice energy. As for τ f value, it is shifted to positive direction, which can be explained in term of the variation in Nb-site bond energy. In addition, the thermal expansion coefficient plays little effect on the temperature stability of ceramics. Typically, the Zn 0.96 Ni 0.04 ZrNb 2 O 8 samples sintered at 1150 °C exhibit excellent properties with ε r  = 27.10, Q · f  = 62,700 GHz and τ f  = −14.72 ppm/°C.