Influence of sintering schedule on the electrical properties of Mn(NO3)2-doped Ba0.92Ca0.08TiO3 PTCR

The relationship of electrical properties of Mn-doped Ba0.92Ca0.08TiO3 PTCR (positive temperature coefficient resistance) ceramics with two sintering schedules was discussed. Using TEM (transmission electron microscope) combined with EDS (energy dispersive X-ray spectrometer), the Mn ions distributed at grain boundaries were analyzed. The results show that the PTCR effect of Mn-doped PTCR ceramics is more dependent on the sintering schedule than those of Mn free.The phenomenon may be caused by the valence states variance of Mn ions segregated at the grain boundaries.