Metal−Insulator Transition Induced by Ce Doping in CaMnO₃

Study of the perovskite-type manganites Ca 1 - x Ce x MnO 3 (0.00 ≤ x ≤ 0.25) has been carried out. The electrical resistivity values for these samples were measured in the temperature range from 300 up to 900 K and show that the doping of the phase CaMnO 3 with cerium induces simultaneously a marked decrease in the electrical resistivity and a metal-to-insulator transition. This behavior is exceptional since such a transition has not been observed to date in these compounds for these experimental conditions and can be attributed to the formation of Mn 3+ ions as a result of charge compensation. The values of metal-to-insulator transition temperature, T MI, change with Mn 3+ amount. Further the carrier doping tends to suppress the semiconductor behavior of CaMnO 3 and the T MI is attributed to charge ordering observed in these compounds around 255 K.