Structural, Raman spectroscopic and microwave dielectric studies on (1-x) NiZrNb_2O_8-x ZnTa_2O_6

摘要

(1 −  x ) NiZrNb~(2)O~(8) −  x ZnTa~(2)O~(6)microwave dielectric ceramics were prepared via the conventional solid-state reaction route. Structural and lattice parameters of the (1 −  x ) NiZrNb~(2)O~(8) −  x ZnTa~(2)O~(6)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 Ni_(2+), Zr_(4+), and Zn_(2+)at A-sites and the substitution of Nb_(5+)and Ta_(5+)at B-sites led to the change of the lattice parameters. There was a gradual transformation in crystal structure from monoclinic phase into Tri-αPbO~(2)phase with the increasing ZnTa~(2)O~(6)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 0.2NiZrNb~(2)O~(8)− 0.8ZnTa~(2)O~(6)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.