Ceramics having nonlinear voltage characteristics comprising the product obtained on preparing a mixture of zinc oxide as a main component, and, as subcomponents, cobalt plus one of praseodymium or terbium, either in an elemental form or as a compound thereof, in an amount of from 0.1 to 8.0 atomic % for the cobalt, from 0.08 to 8.0 atomic % for the praseodymium and from 0.1 to 8.0 atomic % for the terbium, each calculated as cobalt, praseodymium and terbium, and calcining the mixture at a temperature in the range of from about 1150.degree. to about 1400.degree. C and a method for preparing the ceramics. An embodiment includes, as an additional subcomponent, lanthanum, either in an elemental form or as a compound in an amount of from 0.08 to 8.0 atomic %, calculated as lanthanum, with the zinc oxide, cobalt and praseodymium.