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

(1 − x )ZnAl 2 O 4 - x Li 4/3 Ti 5/3 O 4 (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. ZnAl 2 O 4 could not form a solid solution with Li 4 Ti 5 O 12 . With x increasing from 0.2 to 0.8, the phase compositions of ZALT ceramics changed: (ZnAl 2 O 4 and Li 2 ZnTi 3 O 8 , x = 0.2, 0.4) → (ZnAl 2 O 4 , Li 2 ZnTi 3 O 8 and Li 4 Ti 5 O 12 , x = 0.6) → (Li 2 ZnTi 3 O 8 and Li 4 Ti 5 O 12 , x = 0.8), and the main phase changed from ZnAl 2 O 4 ( x = 0.2, 0.4) to Li 2 ZnTi 3 O 8 ( 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 ε r of 13.0–29.0, Q × f values of 30,220–65,580 GHz and τ f values of −51.4 ppm/°C to −20.9 ppm/°C.