ABSTRACT
Positive temperature coefficient of resistance BaTiO3 ceramics containing different donor dopant concentrations of holmium have been studied. An increase in donor dopant concentration from 0.1 to 0.8 at. % Ho results in a reduction in mean grain diameter of an order of magnitude. The grain-boundary segregation of donors has been observed and analysed using energy dispersive X-ray spectroscopy and energy filtered imaging. The potential at the boundary as determined by Fresnel contrast analysis was found to decrease for the higher Ho content sample.
