Enhanced Sinterability and Microwave Dielectric Performance of (1 − x)ZnAl2O4-xLi4/3Ti5/3O4 Ceramics

(1 − x)ZnAl2O4-xLi4/3Ti5/3O4 (ZALT) (x = 0.2, 0.4, 0.6, 0.8) microwave dielectric ceramics were prepared by a solid state reaction method. The preparation, sintering behavior, phase composition and microwave dielectric properties of ZALT ceramics were investigated. ZnAl2O4 could not form a solid solution with Li4Ti5O12. With x increasing from 0.2 to 0.8, the phase compositions of ZALT ceramics changed: (ZnAl2O4 and Li2ZnTi3O8, x = 0.2, 0.4) → (ZnAl2O4, Li2ZnTi3O8 and Li4Ti5O12, x = 0.6) → (Li2ZnTi3O8 and Li4Ti5O12, x = 0.8), and the main phase changed from ZnAl2O4 (x = 0.2, 0.4) to Li2ZnTi3O8 (x = 0.6, 0.8). With increasing x values, the sintering temperature was reduced from 1250°C to 1100°C. ZALT ceramics exhibited microwave dielectric properties with εr of 13.0–29.0, Q × f values of 30,220–65,580 GHz and τf values of −51.4 ppm/°C to −20.9 ppm/°C.