Novel sintering and band gap engineering of ZnTiO3 ceramics with excellent microwave dielectric properties
Pure phase ZnTiO3 ceramics were successfully synthesized for the first time by a solid state reaction method. The synthesis temperature was higher than the phase transition temperature, wherein the ZnO nanoparticles acted as inhibitors to prevent the formation of the secondary phase, Zn2TiO4, which was inevitable by conventional preparation methods. As the small nano-ZnO regions dispersed in the ceramic grains, the bulk diffusion of Ti ions, formation of nucleation centers and migration of phase boundaries were largely suppressed, indicating that nano-ZnO was desirable for stabilizing the ZnTiO3 phase above the phase transition temperature. The R[3 with combining macron] (no. 148) space groups of the single phase were determined by X-ray diffraction Rietveld analysis. X-ray photoelectron spectroscopy and photoluminescence emission spectroscopy were also carried out to investigate the electronic microstructure of the obtained ZnTiO3 phase. Finally, excellent microwave dielectric properties were achieved (εr ∼ 31.5, Q x f ∼ 59 800 GHz and τf ∼ 1.2 ppm °C−1) with a high sintering temperature (900-950 °C). Moreover, given its good chemical compatibility with the Ag electrode and the merits of easy scale-up, high-efficiency, low-cost and environmentally benign synthesis, ZnTiO3 is a promising candidate for LTCC applications. This work paves a great way towards practical applications.