Significantly enhanced sinterability and temperature stability of Li3Mg4NbO8-based microwave dielectric ceramics with LiF and Ba3(VO4)2 addition

Abstract

Li3Mg4NbO8-basic composite ceramics were elaborated via the solid-state reaction process, in which LiF and Ba3(VO4)2 were utilized as a sintering aid and reinforcement phase, respectively. The sinterability, phase assemblage, microstructures, and microwave dielectric performances of Li3Mg4NbO8–LiF–Ba3(VO4)2 composite ceramics were thoroughly researched. The co-addition of LiF–Ba3(VO4)2 can simultaneously lower the sintering temperature and improve the thermal stability of Li3Mg4NbO8-basic ceramics. Solid state activated sintering is responsible for the low-temperature densification of the present ceramics. The coexistence of rock-salt structural Li3Mg4NbO8/Li4Mg4NbO8F and hexagonal structural Ba3(VO4)2 phases was demonstrated by the combinational XRD and SEM-EDS analysis results. The 0.65(Li3Mg4NbO8–LiF)-0.35Ba3(VO4)2 ceramics fired at 825 °C/5 h exhibited promising microwave dielectric performances: τf = 0.5 ppm/°C along with εr = 13.8 and Qxf = 68500 GHz. The good compatibility of the developed ceramics with Ag demonstrates it potential for use in LTCC technology.