The effects of LiF doping on the sintering temperature and microwave dielectric properties of Mg
4Nb
2O
9 (MN) ceramics have been investigated by using a field emission scanning electron microscopy (FE-SEM), X-ray powder diffraction (XRPD), and network analyzer. It was found that the addition of LiF (1.0-10 wt%) to MN is effective in reducing the sintering temperature. The microwave dielectric properties of MN-3.0 wt% LiF sintered at 850°C for 10 h have the dielectric constant (ε
r) of 12.6, the quality factor (
Q•f) of 103607 GHz and the temperature coefficient of resonant frequency (τ
f) of -70.5 ppm/°C. The bulk densities of MN with 3.0 wt% LiF were noticeably improved at the sintering temperature of around 850°C; the value was 4.186 g/cm
3 which was nearly equal to that of MN without LiF sintered at 1350°C. As for the chemical compatibility of MN-3.0 wt% LiF with Ag, the XRPD of the mixtures of MN-3.0 wt% LiF and Ag heat-treated at 920°C for 10 h did not show the evidence of the secondary phase. Thus, it was considered that the MN-
xwt% LiF ceramics are applicable to the multilayer devices with silver as a electrode.
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