Doped nano ZnO powder for varistor application
Kaliyan Hembram, R. Vijay and Tata Narasinga Rao
Conventional non-linear resistors are usually fabricated by solid state mixing of micron sized ZnO powder with oxide dopants such as Bi2O3, Sb2O3, Co2O3, MnO and Cr2O3 with subsequent compaction and sintering. The breakdown voltage is proportional to the number of grain boundaries. High performance non-linear resistor material requires homogeneous distribution of additives, small crystallite size and homogeneous grain boundary defect chemistry. New methods have been developed for the production of doped nanostructured powder for varistor application. Significant improvement in breakdown voltage, coefficient of non-linearity and leakage current has been achieved over conventional powders. The process has already been scaled up to semi-pilot level and field trials are to be initiated shortly in collaboration with Industrial partner.
Comparative size of varistor discs
I-V characteristics of commercial and ARCI varistors
EBSD image of sintered doped ZnO sample
TEM image of doped ZnO nano powder
TEM of doped ZnO nano powder with precipitation of additives/dopants
Nanosilver-candle filter technology has been successfully transferred to a company and the product is in the market with the brand name of PURITECH.
