EXPERIMENTAL EVALUATION OF THE ACCEPTOR-STATES COMPENSATION IN POSITIVE-TEMPERATURE-COEFFICIENT-TYPE BARIUM-TITANATE

Experimental evidence shows that the acceptor-state levels in Sb-doped positive-temperature-coefficient-type BaTiO3 are compensated up to a critical acceptor-state density. Using the slope of the natural logarithm of the resistivity with respect to 1/T, instead of maximum resistivity as a measure for the acceptor-state density, it is possible to estimate this critical value. The value obtained (4.2 x 10(17) m-2) is believed to be the first reported estimate based on experimental data. It is in good agreement with the estimate of 6 x 10(17) m-2 (first reported by Jonker) obtained from the spontaneous polarization of BaTiO3. This shows that the ferroelectric behavior of BaTiO3 is indeed a feasible explanation for the low resistivity below the Curie point, as proposed by Jonker.