Sintering behavior, phase evolution and microwave dielectric properties of thermally stable Li2O-3MgO-mTiO2 ceramics (1≤m≤6)

Li2O-3MgO-mTiO2 (1≤m≤6) ceramics were prepared by the solid state reaction method. X-ray diffraction, energy dispersive spectrometer and scanning electron microscopy techniques were used to investigate the phase composition and crystal structure. With increasing m values, the phase structures of ceramics changed as: (Li2Mg3TiO6, m=1)→(Li2Mg3Ti4O12 and Mg2TiO4, m=2,3)→(Li2Mg3Ti4O12, m=4)→(Li2Mg3Ti4O12, MgTiO3 and Li2MgTi3O8, m=5)→(Li2Mg3Ti4O12, MgTiO3, Li2MgTi3O8 and MgTi2O5, m=6). The optimized sintering temperature was lowered from 1275 °C to 1050 °C. When m=5, Li2O-3MgO-5TiO2 ceramics showed good microwave dielectric properties at a wide sintering temperature range of 1000-1200 °C, and the best microwave dielectric properties of Q×f=71,726 GHz, εr=21.9 and τf=−20.9 ppm/°C were obtained at a relatively low sintering temperature of 1050 °C.