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1.4 CHEMICAL SCIENCES
Nanoparticles of ZnO were prepared by the reaction of ethanolic solutions of zinc acetate and oxalic acid
followed by drying (80 uC) and calcination (500 uC). Subsequently varistor materials were fabricated from this
nanoparticular ZnO via two separate routes:- a) from a ‘‘core shell’’ material using metal salts as additives; b)
by using a conventional solid state mixing of metal oxides. Sintering (1050 uC) and subsequent electrical studies
were carried out for each of these samples and they were compared with commercial varistor samples prepared
under similar conditions. ‘‘Core shell’’ type varistor material showed considerably higher breakdown voltage
(Vc ~ 850 ¡ 30 V mm21) as compared to a sample prepared by mixing with metal oxides (Vc ~ 683 ¡
30 V mm21) or commercial varistor discs (Vc ~ 507 ¡ 30 V mm21). The high breakdown voltage obtained is
attributed to the formation of more varistor-active grain boundaries per unit area.
Pillai, S. C.* et al. (2003) The effect of processing conditions on varistors prepared from nanocrystalline ZnO Journal of materials chemistry, 13, 2003, 2586-2590. doi:10.1039/B306280E
The effect of processing conditions on varistors prepared from nanocrystalline ZnO
Suresh C. Pillai,* John M. Kelly, Declan E. McCormack, Paul O’Brien and Ramesh
Raghavendra, journal of materials chemistry, 13, 2003, 2586-2590.