Phase Evolution and Microwave Dielectric Properties of (1-x)ZnAl_2O_4-xMg_2TiO_4 Ceramics

摘要

(1-x)ZnAl_2O_4-xMg_2TiO_4 microwave dielectric ceramics were synthesized using the solid-state reaction. The variation of the microstructures, phase compositions, and microwave dielectric properties of the (1-x)ZnAl_2O_4-xMg_2TiO_4 ceramics with the amount of Mg_2TiO_4 have been investigated. It can be observed from the XRD results that a single-phase solid solution is formed in the (1-x)ZnAl_2O_4-xMg_2TiO_4 (x = 0.1) ceramics, however, with the increase of x value, second-phase MgTi_2O_5 and MgTiO_3 appear in the (l-x)ZnAl_2O_4-xMg_2TiO_4 ceramics between the range of 0.21≤x≤0.8 and 0.9≤x≤1.0, respectively. As the amount of Mg_2TiO_4 increases, the ε~r valise, of the (1-x)ZnAl_2O_4-xMg_2TiO_4 ceramics increases almost linearly from 9.1 to 14.1, the Q ×f value decreases initially, and then increases rapidly until it attains a maximum value of 256 810 GHz in the (1-x)ZnAl_2O_4-xMg_2TiO_4 (x = 0.92) ceramics, while the τ_f value changes slightly and remains at-(65 ± 5) ppm/℃. When the 6 mol% CaTiO_3 and 5 mol% SrTiO_3 were added to the (1-x)ZnAl_2O_4-xMg_2TiO_4 (x = 0.21), respectively, their τ_f value was successfully controlled within the range of-10≤τ_f≤10 ppm/℃, while the Q ×f value reduced considerably.