Effect of Donor and Acceptor Co-Doping On The Physical Properties of Zno Varistors

ZnO-Bi2O3-MnO2-Co2O3-Sb2O3 (ZBMCS) varistors were prepared via the traditional solid-state method. We investigated the effect of TiN as donor and acceptor on the phase, microstructure and electrical properties of ZBMCS varistors. The result shows that TiN can be used as a grain size regulator to influence the breakdown voltage. Energy dispersion spectroscopy (EDS) analysis of the samples doped with 1.0 mol%TiN shows that the content of N element in grain boundaries is much larger than that in grain, leading to the substitution of N for acceptor Oad" in grain boundaries, forming acceptable defect; The distribution of Ti in ZnO grains and grain boundaries is similar, and Ti distributed in ZnO grains displace Zn, forming donor defects, improving the grain boundary structures and electrical properties of ZnO varistors. We investigated the capacitance-voltage characteristics (C-V) of the ZnO varistors doped with different content of TiN. The result shows that a certain amount of TiN can increase the potential barrier height of the ZnO varistors effectively. The overall performance of the ZnO varistors is the best when TiN doping amount is 1.0 mol%. The maximum nonlinear coefficient α is 41.54, the maximum barrier height Φb is 2.18 eV, the minimum leakage current density JL is 3.52 μA/cm2, the breakdown voltage E1 mA and the minimum tanδ are 380.28 V/mm and 0.05 respectively.