Investigation of the temperature dependent resistivity of La0.80(A1-xAx)0.20MnO3 perovskitee compounds

In this study, manganite compounds doped with ions of +2 valence state and having equal cation size mismatch parameters and equal Mn+4/Mn+3 ratios were produced using the sol-gel method. X-Ray Diffraction patterns of the compounds were used to calculate lattice parameters, unit cell volumes, Mn-O bond lengths and Mn-O-Mn bond angles. The surface morphology of the compounds were examined using Scanning Electron Microscopy (SEM) and the average grain size was calculated. Doping compounds with ions having larger ionic radii increased the average grain size. Temperature dependent electrical resistivity of the compounds were investigated in the from 320K to 10K. Considering the known models which explain the resistivity-temperature relationship, the interactions that contribute to the resistivity of the compounds were revealed. The effect of the bandwidth parameter, which includes the Mn-O bond length and Mn-O-Mn bond angle, on the insulator-metal transition temperatures of the compounds were discussed. It has been shown that as the bandwidth parameter increased, the insulator-metal phase transition temperatures decreased.