Influence of electron beam irradiation on the structural, electrical and thermal properties of Gd_(0.5)Sr_(0.5)MnO_3 and Dy_(0.5)Sr_(0.5)MnO_3 manganites

摘要

We present systematic studies on the effect of electron beam irradiation on structural, electrical and thermal properties of Gd_(0.5)Sr_(0.5)MnO_3 and Dy_(0.5)Sr_(0.5)MnO_3 manganites. The XRD patterns and Rietveld analysis show that the samples remain single phased even after they undergo electron beam irradiation. Both the series of the samples Gd_(0.5)Sr_(0.5)MnO_3 and Dy_(0.5)Sr_(0.5)MnO_3 show insulating trends in their temperature dependent electrical resistivity, ρ(T) behavior. The resistivity data for both the series of samples (pristine as well as irradiated) indicate that the small polaron hopping model is valid in high temperature region; on contrary, variable range hopping model governs the low temperature regime. Magnetic studies demonstrate that the Neel temperatures of pristine and irradiated samples of Gd_(0.5)Sr_(0.5)MnO_3 and Dy_(0.5)Sr_(0.5)MnO_3 do not change appreciably when they are subjected to irradiation. Thermo-electrical power is observed to increase with irradiation in Gd_(0.5)Sr_(0.5)MnO_3 samples, whereas for Dy_(0.5)Sr_(0.5)MnO_3 samples a decrease in thermo-electric power is seen when the samples are irradiated.