Abstract:
The effect of Fe substitution in the polycrystalline La0.67Sr0.33MnO3 has been investigated. Substitution of Fe decreases the Curie temperature of La0.67Sr0.33MnO3 from 370 K to near room temperature in x < 0.3 samples, which show well defined ferromagnetic–paramagnetic transition, whereas x > 0.3 exhibit a frustrated glassy behaviour, evident from the ZFC and FC magnetization data. The magnetic entropy change calculated from the M–H–T data of x = 0.05 and x = 0.1 show broad peak and the respective values of −ΔSM and RCP are found to be about 2.8 J/kg K, 166 J/kg (at TC = 275 K) and 3.3 J/kg K, 153 J/kg (at TC = 266 K) under a field of 50 kOe. Due to the wider distribution of the magnetic entropy, these two compounds can be used as refrigerants for room temperature magnetic refrigeration applications. The critical behaviour of the two compositions was also estimated from the field dependent magnetic entropy change
