The semiconductor properties on the system “metal-semiconductive ferroelectric ceramics-metal”

On barium titanate basis ferroelectric ceramics with semiconductor properties was obtained and it was established that at the different deposited electrodes the dependence of the current intensity through it depending on the applied voltage has a nonlinear character and also presents characteristically marked PTC effect in the vicinity of the ferroelectric phase transition. The electrical properties of the samples of the system as metal-semiconductive ferroelectric ceramics-metal (M-S-M) are dependent on the type of electrode metal (M) and on the method of its deposition on the ferroelectric semiconductor ceramics (S). It was established that all the used electrodes may be divided into two groups: first, those causing the formation of a Schottky type contact layer and second, those forming transition layers on the boundaries of the system M-S. By suitable choice of the electrode material and the deposition method, it is necessary to control the electrical properties of the system M-S-M and in particular to influence on the value of electrical resistance R; to influence on the form of the dependences R(T), R(U) and R(v); to decide on the scale of the PTC effect.