Direct Measurement of the PTC Effect of a Single Grain Boundary

Abstract

PTC (Positive Temperature Coefficient) effects of grain boundaries in a normal PTC thermistor and in a reduced and reoxidized one were directly measured by A. C. complex impedance analysis. The PTC effect and capacitance of a single grain boundary were different with each grain boundary and the PTC effect of the grain boundary with a smaller capacitance tended to be larger. It was considered that the difference in the thickness of the depletion layer of the Schottky barrier in the grain boundary caused the difference in the PTC effect and the capacitance of each grain boundary.