Investigation of the effect of electron beam irradiation on the structural and transport properties of half doped Nd _0.5 Sr _0.5 MnO ₃ manganites

A systematic investigation on the effect of electron beam irradiation on the structural, electrical properties and thermopower of half doped Nd _0.5 Sr _0.5 MnO ₃ manganites is presented in this report. Elemental analysis of the samples through Energy Dispersive X-ray Spectroscopy (EDS) confirm the desired stoichiometry. Rietveld refinement of the X Ray diffraction data reveals that the samples are single phased. Further, no change in crystal structure or symmetry is observed as an after-effect of electron beam radiation. The samples exhibit insulating behaviour in the entire temperature range 10–300 K. Though the resistivity value changes as a result of electron beam irradiation but the insulating behaviour is unaffected. It is validated from both resistivity as well as thermopower analysis that small polarons are responsible for conduction in the high temperature region. On the contrary, variable range hopping is responsible for the conduction mechanism at low temperatures. The absolute value of thermopower is observed to decrease with increasing dose of electron beam. Moreover, thermopower data indicates n-type conductivity for the samples under investigation.