ZnO varistors with and without surfactant such as sodium dodecyl sulphate (SIDS) are prepared by nitrate-combustion process. The samples were identically heat treated and sintered at 1000 degrees C for 12 h to study the influence of the surfactant on the nonlinear electrical properties of polycrystalline ZnO. It is observed that the nonlinear coefficient decreases marginally (alpha = 35) for samples prepared with surfactant, whereas breakdown field (E-B = 130 V/mm) decreased significantly. The corresponding parameters for the samples synthesized without surfactant are alpha = 45 and E-B = 400 V/mm. Hence, this method can be used for the manufacture of varistors with low to moderate breakdown fields. (c) 2005 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

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