Ultralow loss and temperature stability of Li3Mg2NbO6-xLiF ceramics with low sintering temperature

Novel temperature stable Li3Mg2NbO6-xLiF (x = 0.5–8 wt %) ceramics with ultralow loss were fabricated by the solid-state reaction process. The influence of LiF addition on the sintering, grain growth and morphology, and improved microwave dielectric characteristics was investigated. A single orthorhombic Li3Mg2NbO6 structure could be confirmed by Raman spectra and XRD patterns. Dense and homogeneous microstructure could be obtained with ∼10 μm average grain size. Results demonstrated that the er values were relevant to bulk density and the high Q×f values were influenced by the large grain sizes. The τf values depend on porosity corrected dielectric constant. Notably, the remarkably desirable microwave dielectric characteristics: er = 15.4, Q×f = 100,000 GHz, τf = −3.1 ppm/°C were achieved for the Li3Mg2NbO6 ceramics with x = 6 wt% sintered at 925 °C, which could be applied for ultra-low loss LTCC applications.