Effect of annealing atmosphere on characteristics of kaolin-doped zinc oxide disks

Abstract

This study elucidates the effect of the annealing environment (oxygen and nitrogen) on the properties of kaolin-doped ZnO disks. The findings showed that, in comparison to the sample annealed in O2 ambient, the sample annealed in N2 has a greater average grain size. The tensile stress, lattice constants, and crystallite size of the (002) plane all indicate that annealing under N2 enhanced the crystal quality of the ZnO disk. The bandgap energy shifted from 3.09 to 2.96 eV because of the doping and annealing processes. By annealing the kaolin-doped ZnO disk under N2 atmosphere, the intrinsic defects were almost eliminated. The nonlinear coefficient of the disks varied from 3.6 to 2.0. It was proven in this study that kaolin can be used as an effective dopant/additive for ZnO varistors.