Dielectric properties of Na0.5Bi Ti3.98Mg0.02O (x=4.48, 4.50, 4.52) ceramics under different Bi contents and sintering temperatures

As a new kind family of lead-free Na0.5Bi0.5TiO3 (NBT) ceramics, bismuth layer-structured ferroelectrics (BLSFs), Na0.5BixTi3.98Mg0.02Oy (x = 4.48, 4.50, 4.52) were synthesized by a conventional mixed oxide route. Studies have found that the dielectric properties of Na0.5Bi4.5Ti4O15 can be optimized through changing the Bi content of the ceramics or Mg-doping on Ti-site under different sintering temperatures. X-ray diffraction analysis indicated that the new material was in a single BLSFs phase. The dielectric constant of Mg-doped Na0.5Bi4.5Ti3.98Mg0.02Oy was improved and dielectric loss of Na0.5Bi4.5Ti3.98Mg0.02Oy changed slowly under 500 °C with the increased sintering temperature. We found that the dielectric properties of the sample sintered at 1120 °C with the highest permittivity of 1122.5 and the lowest dielectric loss of 0.01 were relatively better than those of the other samples. SEM can be better to explain the results of the dielectric spectrum at different sintering temperatures through grain size mechanics. Z* plots showed that Na0.5Bi4.5Ti3.98Mg0.02Oy ceramics are a kind of dielectrics. Thus, Na0.5BixTi3.98Mg0.02Oy (x = 4.48, 4.50, 4.52) can be used as high-temperature capacitors and phase shifter with high dielectric constant, low dielectric loss and wide operating temperature range.