Electrical properties and microstructure of CuO ceramics containing small amounts of alkaline earth elements

In order to develop suitable materials for ceramic resistors as a final target, basic investigation about electrical properties and microstructure of CuO ceramics doped with some amounts of alkaline earth oxide was performed. The resistivity of CuO ceramics containing additives (MgO, SrO, BaO) with a certain concentration range were lower and showed peculiarly better near linearity in a high applied field of 500 kV/m compared with that of non-doping CuO ceramics. Results of microstructure and crystalline phase analyses of these samples indicated that the additive small grains, whose size was sub-micrometer order, were present dispersively into the CuO grains. Such the change of microstructure of CuO ceramics was thought to induce the peculiar electric properties.