A systematic study on effect of electron beam irradiation on electrical properties and thermopower of RE0.8Sr0.2CoO3 (RE=La, Pr) cobaltites

The effect of electron beam (e-beam) irradiation on the crystal structure and transport properties of polycrystalline samples of La0.8Sr0.2CoO3 (LSCO) and Pr0.8Sr0.2CoO3 (PSCO) cobaltites is reported in this communication. The of X-ray diffraction data reveals that the pristine and irradiated compounds of LSCO and PSCO samples are single phased having rhombohedral structure with R-3C space group. It is noticed that the crystal structure is preserved even after irradiation. Nonetheless the unit cell parameters are slightly altered when exposed to e-beam. The resistivity patterns of LSCO and PSCO samples demonstrate the occurrence of semiconducting behavior over the measured temperature range of 10-300 K. From the analysis of the temperature dependent resistivity data on the bulk samples, it is seen that small polaron hopping (SPH) mechanism is more dominating in the high temperature region of the pristine sample as compared to e-beam irradiated samples of LSCO and PSCO. The Seebeck coefficient (S) data of all the batches of LSCO and PSCO samples predominantly display positive values over a vast temperature region, indicating that holes are the dominant charge carriers. The investigation of S measurements confirms the validity of SPH mechanism in the high temperature region.