Materials Research Bulletin, Vol. 32, No. 2, pp. 239-247,1997 Copyright 0 1997 Elswier Sciawe Ltd Printed in the USA. All rights reserved 0025-5408/97 $17.00 +.OO Pergamon PI1 SOO2s-5408(96)00175-4 SYNTHESIS OF ZnO NANOPARTICLES FOR VARISTOR APPLICATION USING Zn-SUBSTITUTED AEROSOL OT MICROEMULSION M. Singbal, V. Cbbabra, P. Kang and D.O. Shah* Center for Surface Science and Engineering and Departments of Chemical Engineering & Anesthesiology University of Florida, Gainesville, Florida 32611 USA (Refereed) (Received May 7, 1996; Accepted July 8, 1996) ABSTRACT This paper describes a new method for the synthesis of zinc oxide nanoparticles using ethanol-in-oil microemulsions with Zn-DEHSS (diethylbexyl sulfosuccinate) as surfactant. The zinc oxide nanoparticles find application in varistors and other functional devices. These particles have been characterized by X-ray dimaction, TEM, and BET surface area. Microemulsion droplets were characterized by quasi elastic light scattering (QELS). Varistors formed from doped zinc oxide nanoparticles finds application as low voltage surge devices with low leakage current and high coefficient of nonlinearity zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLK (a). In this paper, we have shown that the critical voltage of the varistor is related to the grain size which is related to size of ZnO particles. The smaller ZnO particles lead to larger grain size, thereby lowering the critical voltage. zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCB copydght Q 1997 Eher science zyxwvutsrqponmlkjihgfedc Ltd KEYWORDS: A. nanostructures, A. oxides, C. electron microscopy, C. X- ray diffraction, D. electrical properties INTRODUCTION Nanophase ceramics have found many applications in science and technology because of the improvements in a variety of properties that are expected to result from the reduction in particle size to nanometer scale [ 11. Zinc oxide varistors are electronic ceramic devices, the primary function of which is to sense and limit transient voltage surges and to do so *To whom all correspondence should be addressed. 239