Crystal structure and improved microwave dielectric properties of ZnZr_((1_x))Ti_xNb_2O_8 ceramics

摘要

In this work, ZnZr_((1_x))Ti_xNb_2O_8 (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) ceramics were synthesized using solid-state reaction method. Rietveld refinement and Raman analysis were employed to investigate the correlation between crystal structure and microwave dielectric properties. Substitution of Ti~(4+) for Zr~(4+) promoted grain growth and ceramic sintering, which is confirmed by SEM results and relative density. Second phase (ZnTiNb_2O_8), which had poorer microwave dielectric properties than that of ZnTiNb_2O_8 ceramics, occurred when ⅹ ＞ 0.4 because of exceeded solution limit. However, Ti~(4+) ions enter Zr sites when x≤0.3, and this then affects A/B-site bond lengths and structural characteristics of NbO_6 octahedron. This improved microwave dielectric properties and mainly, promoted quality factor (Q xf). Moreover, excellent microwave dielectric properties of ε_r=29.75, Q ×f= 107,303 GHz, and τ_f=-24.41ppm/°C were obtained for ZnZr_(0.8)Ti_(0.2)Nb_2O_8 (x = 0.2) ceramics sintered at 1150 °C. Thus, the material has a good application prospect in microwave devices.