The Relationships Between Structures and Microwave Dielectric Properties of Li2Zn1-x Co x Ti3O8 Ceramics

Li2Zn1-xCoxTi3O8 (0.02 <= x <= 1) ceramics were synthesized by the conventional solid-state ceramic route. The relationships between the structures and microwave dielectric properties of Li2Zn1xCoxTi3O8 ceramics were thoroughly studied by structure refinement. The x-ray diffraction patterns showed that all the compositions exhibited a single spinel structure. The substitution of Co could decrease the densification temperatures of Li2Zn1-xCoxTi3O8 ceramics. The dielectric constants (epsilon(r) ) were affected by the dielectric polarizabilities. The variation of quality factor (Q x f) values was consistent with that of packing fractions. The temperature coefficients of resonant frequency (tau(f)) moved towards the positive due to the composition. Typically, the Li2Zn0.94Co0.06Ti3O8 ceramic sintered at 1075 degrees C for 4 h exhibited epsilon(r) = 26.2, Q x f = 90,400 GHz, tau(f) = -11.4 ppm/degrees C, and the Li2Zn0.4Co0.6Ti3O8 ceramic sintered at 1050 degrees C for 4 h showed epsilon(r) = 25.5, Q x f = 59,300 GHz, tau(f) = -1.5 ppm/degrees C.