Structural, Raman spectroscopic and microwave dielectric studies on (1 − x) NiZrNb₂O₈ − x ZnTa₂O₆

Abstract

(1 − x) NiZrNb₂O₈ − x ZnTa₂O₆ microwave dielectric ceramics were prepared via the conventional solid-state reaction route. Structural and lattice parameters of the (1 − x) NiZrNb₂O₈ − x ZnTa₂O₆ ceramics were analyzed through X-ray diffraction, Raman spectra, and scanning electron microscopy. The results showed that there were serious ionic diffusion and solid solution reaction in the composite ceramics. The substitution of Ni²⁺, Zr⁴⁺, and Zn²⁺ at A-sites and the substitution of Nb⁵⁺ and Ta⁵⁺ at B-sites led to the change of the lattice parameters. There was a gradual transformation in crystal structure from monoclinic phase into Tri-αPbO₂ phase with the increasing ZnTa₂O₆ content. With the increase of x value from 0 to 1, the ε_r value increased from 23.76 to 35.71 and the Q × ƒ value increased from 32107 to 46709 GHz. The temperature frequency resonance coefficient near zero could be obtained at x = 0.8. The 0.2NiZrNb₂O₈ − 0.8ZnTa₂O₆ ceramics were obtained at 1275 °C with excellent microwave dielectric properties: ε_r ~ 33.69, Q × ƒ ~ 37,529 GHz and τ_ƒ ~ + 2.56 ppm/°C.