Influence of Ni2+ Substitution for Zn2+ on Microwave Dielectric Properties of Zn1-xNixZrNb2O8 Ceramics

Dependence of microwave dielectric properties on the crystal structure of Zn1-xNixZrNb2O8 was investigated as a function of NiO content (x = 0, 0.02, 0.04, 0.06, 0.08). Pure single phase with monoclinic wolframite structure was obtained through solid-state reacti. The unit-cell volume of the specimens decreased with NiO content because of the smaller ionic radius of Ni2+ than Zn2+. Dielectric constant (K) of the sintered specimen was affected by bond-ionicity. Quality factor (Q x f(0)) was analyzed depending on the lattice-energy. With the increase of Ni2+, temperature coefficient of resonant frequency (tau(f)) of specimens increased due to the increase of B-site bond energy. The sample of Zn1-xNixZrNb2O8 (x = 0.08) sintered at 1250 degrees C for 4 h showed excellent microwave dielectric properties, epsilon(r) of 25.72, Q x f(0) value of 73224 GHz, and tau(f) of - 39.14 ppm/degrees C.