Sintering behavior, microstructure and microwave dielectric properties of Li₂MgTi₃O₈ modified by LiF

Abstract

Sintering behavior, microstructure and microwave dielectric properties of Li₂MgTi₃O₈ ceramics modified by LiF have been studied by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), thermal dilatometry and with a network analyzer at the frequency of about 6–10 GHz. The addition of LiF to Li₂MgTi₃O₈ led to the formation of trace amounts of MgF₂(ss), and Li₂TiO₃(ss) secondary phases, which reduced the sintering temperature to 850 °C without affecting its microwave dielectric properties. In contrast, the LiF-doped composition exhibited single phase solid solution with ordered spinel structure after sintering at 900 °C/2 h, and MgTi₂O₅ secondary phase appeared after sintering at 1100 °C/2 h. An excellent combined microwave dielectric properties with ε _r of ~27.8, Q × f of ~63,000 GHz and τ _f of ~−4.1 ppm/°C could be obtained for the LiF-added composition with x = 0.15 sintered at 850 °C/2 h. The x = 0.15 composition was chemically compatible with Ag powders after sintering at 850 °C for 2 h.