Effect of Mg doping on the transport properties and magnetoresistance of La2/3Ca1/3MnO3 prepared in low temperature

The influence of Mg substitution for Ca in La2/3Ca1/3MnO3 prepared by a sol–gel method followed by sintering at 1000 °C has been investigated, in the light of structure, electric transport and magnetoresistance properties. The 10% substitution of Mg for Ca causes the insulator–metal transition temperature (TP) increase from ∼170 to ∼250 K. With further increasing the Mg concentration, TP decreases. The samples doped with Mg show smaller MR in low temperature region (T < TP) and smaller activation energy Ea in the insulating region (T > TP). The observed results are analyzed in terms of that Mg mainly acts as a flux and the samples doped with Mg have larger grain size than pure La2/3Ca1/3MnO3.