Phase Constitutions and Microwave Dielectric Properties of Zn₃Nb₂O₈–TiO₂

Abstract

The phase constitutions and microwave dielectric properties of (1- x )Zn 3 Nb 2 O 8 – x TiO 2 were investigated using X-ray powder diffraction and a network analyzer, respectively. Four mixture regions were studied with increasing TiO 2 content ( x ): (1) Zn 3 Nb 2 O 8 , ZnNb 2 O 6 , and Zn 2 TiO 4 , (0< x ≤0.5) (2) ZnNb 2 O 6 and Zn 2 TiO 4 , (0.5< x <0.65) (3) Zn 2 TiO 4 , ZnTiNb 2 O 8 , and TiO 2 (0.65≤ x ≤0.75), (4) Zn 2 TiO 4 and TiO 2 (0.75< x <1). This structural evolution with composition was ascribed to the interrelations between Zn 3 Nb 2 O 8 and TiO 2 . It was demonstrated that the microwave dielectric properties correlated to crystal structure rather than chemical composition. In the mixture region of Zn 2 TiO 4 , ZnTiNb 2 O 8 , and Zn 2 TiO 4 , the amount of TiO 2 and ZnTiNb 2 O 8 considerably increased and decreased, respectively, with increasing TiO 2 content ( x ). This resulted in the increase of relative dielectric constant ( ε r ) and temperature coefficient of resonant frequency (τ f ). At x =0.725, Q × f is 5190 GHz, ε r and τ f are 36 and 4 ppm/°C, respectively.