The Resistivity of MgO Powder at Elevated Temperatures

A simple apparatus is described for the measurement of resistivity of dielectric powders at elevated temperatures. MgO powder is tested in the range of temperatures from room temperature to 500°C. A large decrease of resistivity is observed at about 50°C, which is in contrast to a previously reported decrease of resistivity in single crystals of MgO at much lower temperatures. The iron content in the samples of typical purity is sufficient to cause a significant lowering of the activation energy for conduction in MgO, but it is not clear why the increased conduction occurs in a narrow range of temperatures.