Mg(Ti
1-xNb
x)O
3 (x = 0–0.09) ceramics were prepared by the conventional solid-state reaction method. The phase composition, sintering characteristics, microstructure and dielectric properties of Ti
4+ replacement by Nb
5+ in the formed solid solution Mg(Ti
1-xNb
x)O
3 (x = 0–0.09) ceramics were systematically studied. The structural variations and influence of Nb
5+ doping in Mg(Ti
1-xNb
x)O
3 were also systematically investigated by X-ray diffraction and Raman spectroscopy, respectively. X-ray diffraction and its Rietveld refinement results confirmed that Mg(Ti
1-xNb
x)O
3 (x = 0–0.09) ceramics crystallised into an ilmenite-type with R-3 (148) space group. The replacement of the low valence Ti
4+ by the high valence Nb
5+ can improve the dielectric properties of Mg(Ti
1-xNb
x)O
3 (x = 0–0.09). This paper also studied the different sintering temperatures for Mg(Ti
1-xNb
x)O
3 (x = 0–0.09) ceramics. The obtained results proved that 1350 °C is the best sintering temperature. The permittivity and
Q ×
f initially increased and then decreased mainly due to the effects of porosity caused by the sintering temperature and the doping amount of Nb
2O
5, respectively. Furthermore, the increased
Q ×
f is correlated to the increase in Ti–O bond strength as confirmed by Raman spectroscopy, and the electrons generated by the oxygen vacancies will be compensated by Nb
5+ to a certain extent to suppress Ti
4+ to Ti
3+, which was confirmed by XPS. The increase in τ
f from ?47 ppm/°C to ?40.1 ppm/°C is due to the increment in cell polarisability. Another reason for the increased τ
f is the reduction in the distortion degree of the [TiO
6] octahedral, which was also confirmed by Raman spectroscopy. Mg(Ti
0.95Nb
0.05)O
3 ceramics sintered at 1350 °C for 2 h possessed excellent microwave dielectric properties of ε
r = 18.12,
Q ×
f = 163618 GHz and τ
f = ?40.1 ppm/°C.
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