Effect of TiO2 on phase composition and microwave dielectric properties of Zn1.01Nb2O6 ceramics

Nonstoichiometry has been playing an important role in the microwave dielectric performance of columbites A(2+)Nb(2)O(6) (A(2+) = Ca, Mg, or a transition metal). Herein, with an excess of 0.01 mol Zn, the Qxf values of ZnNb2O6 ceramics could be effectively improved from 121,000 GHz to 138,000 GHz. On the basis of high-Q Zn1.01Nb2P6 ceramics, TiO2 was chosen to further tune the tau(f) values for the matrix materials prepared by the conventional solid-state reaction method. The results showed that, with the increase of TiO2 content, the ZnNb2O6-based ceramics underwent four phase regions: columbite (ZnNb2O6) solid solution, ixiolite (ZnTiNb2O8) solid solution, mixture of ZnTiNb2O8 and rutile (Zn1/3Nb2/3)(0.5)Tio(0.5)O(2), and (Zn1/3Nb2/ (3))(0.5)Tio(0.5)O(2) solid solution. Such changes in phase formation had an important influence on the microwave dielectric behavior of (1-x)Zn1.01Nb2O6-xTiO2 ceramics. Importantly, tau(f) could be tuned from 15.3 ppm/ degrees C to +13.9 ppm/ degrees C along with x increased from 0.58 to 0.6. Accompanied with epsilon(r) approximate to 44.64 similar to 47.43 and Qxf >= 12,300 GHz, these materials are promising candidates for applications in microwave components and devices.