Metal Oxide Varistor: Zinc Oxide with 0.2 % Bismuth Oxide, 1000 °C, 0.5 mm (Masuyama 1972)

A non-linear resistor: the current through it rises far faster than the voltage across it. Masuyama, Matsuoka and Nishi made one from zinc oxide with a little bismuth oxide: pressed into a disc, sintered, lapped, and given metal electrodes. With 0.2 mole % bismuth oxide, sintered at 1000 °C and lapped to 0.5 mm, the disc measured a C-value of 21 at 1 mA and a nonlinearity exponent n of 4.5. Source: T. Masuyama, M. Matsuoka and T. Nishi (Matsushita), US 3,663,458 (1972), Example 1. Unknown: how the aluminium is sprayed on and what the silver paint is. The patent calls both well known, so they are linked to unknown heads. The 10 g batch is our arithmetic. Picture: the patent's drawing.