Abstract :
The effect of Pr doping at the La site on electrical and thermal transport properties of the electron-doped manganites La0.9−xPrxTe0.1MnO3 ( 0 ≤ x ≤ 0.9 ) has been investigated. For the samples with x ≤ 0.36 , there is a insulator–metal (I–M) transition while the samples with x ≥ 0.54 display semiconducting behavior over the whole measured temperature range. For x ≤ 0.36 , the thermopower S changes sign from negative to positive with decreasing temperature and the crossover temperature increases with increasing Pr doping content x . For the samples with x ≥ 0.54 , S shows a positive sign over the whole temperature range studied. Both ρ ( T ) and S ( T ) data in the high temperature range can be well described by the variable-range-hopping (VRH) model for all samples studied. In the low temperature region, the ρ ( T ) and S ( T ) data for the sample with x ≤ 0.36 are analyzed on the basis of the electron–magnon scattering mechanism. As regards the thermal conductivity k ( T ) , the low temperature k peak is suppressed by Pr doping and k decreases with increasing Pr doping level. The result is analyzed as regards the combined effect of the disorder and antiferromagnetic (AFM) interaction induced by Pr doping.
