Defect and electrical conduction in Mn-doped CaCu3-xMnxTi4O12 negative temperature coefficient ceramics

•The defect and electrical conduction in ceramics have been successfully investigated.•Linear electrical behaviors can be enhanced by the substitution of Mn ions.•The defect may result from the cation non-stoichiometry at the low temperature.•The defect may result from the oxygen vacancy at the high temperature.

The defect and electrical conduction in Mn-doped CaCu3-xMnxTi4O12 (0 ≤ x ≤ 1) negative temperature coefficient (NTC) ceramics were successfully investigated by using defect chemistry theory in combination with X-ray photoelectron spectroscopy (XPS) analysis. An approximate linear relationship between the natural logarithm of the resistivity and the reciprocal temperature for Mn-doped samples was observed in comparison to CaCu3Ti4O12, and these linear electrical behaviors were extremely enhanced with increasing Mn content. As the Mn concentration increased, Ea25-500◦C decreased and Ea500-800◦C increased at first and then slightly decreased. The defect in these ceramics may mainly result from the cation non-stoichiometry in the temperature range from ambient to 500 °C and oxygen vacancy after 500 °C.