Microwave dielectric properties, low-temperature sintering mechanism, and defects behaviour of temperature stable (1-x)Li2Zn3Ti4O12-xSr3(VO4)2 ceramics

Abstract

(1-x)Li2Zn3Ti4O12-xSr3(VO4)2 (0.1 ≤ x ≤ 0.4) microwave dielectric ceramics were fabricated by solid-state sintering technology. The impact of SV addition on the microstructure, dielectric properties, sintering process, and defects behaviour was studied. The formation of SrTiO3 and the glass phase were observed via XRD and TEM, and the latter resulted in a decrease in the sintering temperature. The variations in microwave dielectric properties were consistent with the empirical mixture rules calculated by XRD refinement, and a near-zero τf value was obtained. The Li, Zn and V elements of the glass phase and the liquid phase sintering model were deduced via DSC, TEM and Raman spectroscopy. Then, the defect behaviour, such as oxygen vacancies, Ti3+, and V4+, was investigated by XPS and complex impedance spectroscopy. It was found that the generation and migration of defects occurred much more easily in 0.7LZT-0.3 SV than in LZT, resulting in a higher dielectric loss. Finally, the 0.7Li2Zn3Ti4O12-0.3Sr3(VO4)2 ceramic sintered at 900 °C exhibited excellent microwave dielectric properties of εr = 17.8, Q × f = 41,891 GHz, and τf = −4.4 ppm/°C and good compatibility with silver electrode, showing a good potential application for LTCC.