Electronic conduction through a grain boundary in BaTiO_3 positive temperature coefficient thermistors

摘要

The conduction mechanism through a single grain boundary in positive temperature coefficient thermistor was investigated by a combination of direct measurements using bicrystals of niobium-doped barium titanate and a device simulation analysis. The potential barrier model with a n-i-n structure an consistently interpret the observed electric properties rather than the double Schottky barrier model. The absence of a sub-ohmic behavior in the current-voltage characteristics and excess low-frequency capacitance at zero-bias are caused by the spatially distributed traps at the insulating layer.