K-substitution induced electrical band gap engineering in La1-xKxMnO3 manganites

In this communication, we report the results of the studies on structural and transport properties of La1-xKxMnO3 (LKMO: 0.0 ≤ x ≤ 0.3) manganites synthesized by conventional solid state reaction method. Structural investigations on all the samples have been carried out by performing XRD measurement and Rietveld refinements of the raw data. All the samples show metal to insulator (semiconducting) transition at TP. Charge transport in semiconducting region of all the samples has been discussed by fitting various theoretical mechanisms and models to the resistivity data. Mott type VRH model has been found to be appropriate mechanism to understand the charge transport and related calculated activation energy (E) has been discussed in the light of carrier localization length. Variation in E with x has been explained on the basis of zener double exchange (ZDE) mechanism and possible Mn4+ − O2− − Mn4+ AFM type interaction in the system.