Mn-doped La_(0.1)Sr_(0.9)TiO_3 for intermediate temperature NTC thermistor applications

To explore perovkite-structured oxides for negative temperature coefficient (NTC) thermistor applications,La0.1Sr0.9TiO3 was doped by Mn. It was found that partial substitution of Ti by Mn in La0.1Sr0.9TiO3 can result in a drastic decrease in electrical resistivity ρ and thermal constant B. For La0.1Sr0.9Ti0.9Mn0.1O3,ρ at 300 ℃ was measured to be 3.0×102 Ω·m,and B was 5 900 K,which are all much smaller than those for the undoped sample (ρ=9.8×104 Ω·m,B=13 000 K). Mn doping also inhibited the drift in electrical resistivity with time. The improved electrical properties are attributed to the presence of Mn3+—O—Ti4+ network in the Mn-doped materials. The Mn-doped La0.1Sr0.9TiO3 may be used as intermediate temperature NTC thermistors.