Phase constitutions and microwave dielectric properties of Zn3Nb2O8-TiO2

The phase constitutions and microwave dielectric properties of (1 - x)Zn3Nb2O8-xTiO(2) were investigated using X-ray powder diffraction and a network analyzer, respectively. Four mixture regions were studied with increasing TiO2 content (x): (1) Zn3Nb2O8, ZnNb2O6, and Zn2TiO4, (0 < x < 0.5) (2) ZnNb2O6 and Zn2TiO4, (0.5 < x < 0.65) (3) Zn2TiO4, ZnTiNb2O8, and TiO2 (0.65 < x < 0.75), (4) Zn2TiO4 and TiO2 (0.75 < x < 1). This structural evolution with composition was ascribed to the interrelations between Zn3Nb2O8 and TiO2. It was demonstrated that the microwave dielectric properties correlated to crystal structure rather than chemical composition. In the mixture region of Zn2TiO4, ZnTiNb2O6, and Zn2TiO4, the amount of TiO2 and ZnTiNb2O8 considerably increased and decreased, respectively, with increasing TiO2 content (x), This resulted in the increase of relative dielectric constant (epsilon (r)) and temperature coefficient of resonant frequency (tau (f)). At x = 0.725. Q x f is 5190 GHz, epsilon (r) and tau (f) are 36 and 4 ppm/degreesC, respectively.