With the interest in using lead-free materials to replace lead-containing materials increasing,the use of Na0.5Bi0.5TiO3 (NBT) has come into our sight.We studied the composition of NBT and found that NaBiTi6O14 ceramics can be compositionally tuned by Mg-doping on the Ti-site to optimize the dielectric properties.In this study,Mg-doped NaBiTi6O14 (NaBi(Ti0.98Mg0.02)6O14-δ) ceramics were prepared by a conventional mixed oxide route at different sintering temperatures,and their dielectric properties have been studied at a wide temperature range.X-ray diffraction (XRD) pattes of the NBT-based ceramics indicate that all samples have a pure phase without any secondary impurity phase.The experimental data show that after Mg-doping,the relative permittivity and dielectric loss become lower at 1040,1060,and 1080 ℃ except 1020 ℃ and at different frequencies from 10 kHz,100 kHz to 1 MHz.Take 1060 ℃ for example,when the sintering temperature is 1060 ℃ at 1 MHz,the minimum relative permittivity of NaBiTi6O14 is 32.9 and the minimum dielectric loss is 0.01417,the relative permittivity of NaBi(Ti0.98Mg0.02)6O14-δ under the same condition is 25.8 and the dielectric loss is 0.000104.We explored the mechanism of Mg-doping and surprisingly found that the dielectric property of NaBi(Ti0.98Mg0.02)6O14-δ becomes better owing to Mg-doping.Thus,NaBi(Ti0.98Mg0.02)6Ot4-δ can be used in microwave ceramics and applied to new energy materials.