Synthesis and Characterization of Nanocrystalline Doped-ZnO Powder for Advanced Varistor Application

The nanocrystalline doped ZnO powder has been synthesized by solution combustion method using sucrose as fuel and zinc acetate as oxidant. The as-prepared nanopowders were characterized by XRD, showing particle size approximately 39 and 48 nm for fuel to oxidant ratio of 1:1 (stoichiometric) and 2:1 (fuel rich). The powders were compacted and sintered for 9 hours. The sintered samples were characterized by SEM and XRD, showing the presence of spinel (Zn7Sb2O12) and pyroclore (Zn2Bi3Sb3O14) phases at intergranular spacing. The phase distribution [spinel (Zn7Sb2O12), pyroclore (Zn2Bi3Sb3O14), beta-Bi2O3, and delta-Bi2O3] was found to be more homogeneous in case of samples obtained by adding the stoichiometric amount of fuel. The current-voltage (J-E) characterization shows the high non-linearity coefficient (alpha) similar to 22 and break-down voltage (V-B) of similar to 0.41 kV/mm for the fuel rich sample.