Microwave Dielectric Properties of Low‐Fired ZnNb ₂ O ₆ Ceramics with BiVO ₄ Addition

Abstract

The BiVO 4 additive was found effective for low‐temperature firing of ZnNb 2 O 6 polycrystalline ceramics below 950°C in air without a serious degradation in their microwave dielectric properties. Dense BiVO 4 ‐doped ZnNb 2 O 6 samples of a relative sintered density over 95% could be prepared even at 925°C. An optimally processed specimen exhibited excellent microwave dielectric properties of Q · f = 55000 GHz, ɛ r = 26, and τ f =−57 ppm/°C. With increasing BiVO 4 addition up to 20 mol% relative to ZnNb 2 O 6 , while the quality factor Q · f was gradually decreased, the relative dielectric constant, ɛ r , was linearly increased and the temperature coefficient of resonant frequency, τ f , was slightly increased. The variations in Q · f and ɛ r are surely attributable to the residual BiVO 4 in the ZnNb 2 O 6 matrix. An unexpected slight increase in τ f is probably due to the formation of the Bi(V,Nb)O 4 ‐type solid solution.