Abstract
Using the polycrystalline disk of NiZn and CuZn ferrites with a resistivity of 10 2-10 4Ω⋅m, the local current path was formed by applying an electric field up to the extent of the breakdown voltage between the plate electrode on one face of the disk and the needle electrode on the other face. We named this procedure as “Conduction Treatment”. It was found that after me conduction treatment, this specimen shows the nonlinear negative resistance such as so-called switching phenomena of amorphous semiconductor.
From the optical microscopic observations, it was clarified that 1) the current path was separated by the thin gap from the surrounding bulk of ferrite, 2) the current path phase has larger grain size than those of the surrounding materials, 3) the current path has many crevices along it, 4) when the current flows, all the parts of crevices is bright as if it discharges.
The voltage-current characteristics were examined in details on the samples with a small amount of additives of various metal oxides.
