Preparation of low-temperature sintered (Bi_1.5Zn_0.5)(Zn_0.5Nb_1.5)O₇ ceramics doped by CuO in different methods

(Bi_1.5Zn_0.5)(Zn_0.5Nb_1.5)O₇ (BZN) ceramics were synthesized by the traditional solid-state reaction method, using Bi₂O, ZnO, and Nb₂O₅ powders as raw materials. The surface of BZN powders was modified by CuO coating layer, and the CuO sintering aid was introduced instead of directly mixing BZN and CuO powders. The CuO coating layer was prepared with CuSO₄ solution as the precursor solution, and the addition of CuO could be reduced by using liquid coating method, thereby reducing the negative impact of CuO on the dielectric properties of BZN ceramics. The results show that, in liquid coating method, when the concentration of CuSO₄ solution is 0.5 mol/L, the sintering and densification process of BZN ceramics can be promoted. The optimal dielectric properties of BZN ceramics are obtained by sintering for 3 h at 900, the dielectric constant is℃ 141, the quality factor is 426 GHz, and the temperature coefficient of resonance frequency is —357×10^-6/℃ (4 GHz), which are much better than those obtained by solid-phase mixing method, that is to say, the dielectric constant is 134, the quality factor is 287 GHz, and the temperature coefficient of resonance frequency is —374×10^-6/℃ (4 GHz).