Tuning the magnetocaloric properties of nanomagnetic materials for magnetic refrigerant applications

Abstract

Magnetic refrigeration based on the magnetocaloric effect is becoming an emerging technology to replace conventional gas compression refrigeration as it is environmentally friendly, compact and highly efficient. Materials with magnetocaloric properties close to room temperature will be preferred for residential and commercial use as magnetic refrigerants. This research explores synthesis, characterisation and magnetocaloric properties of perovskite manganites, ferrites and nanocomposites. The structural, compositional, magnetic and magnetocaloric properties of the lanthanum sodium manganite (La0.5Na0.5MnO3) and cobalt substituted lanthanum sodium manganite (La0.5Na0.5CoxMn1-xO3) in the perovskite system, cobalt substituted copper ferrite (CuxCo1-xFe2O4) and zinc substituted copper ferrite (CuxZn1-xFe2O4) in the ferrite system and cobalt polystyrene nanocomposites samples are investigated by employing X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Fourier-transform Infrared spectroscopy (FTIR), Energy-Dispersive X-ray spectroscopy (EDAX), and Vibrating Sample Magnetometry (VSM). The magnetocaloric properties of the samples are analysed around the transition temperature which is determined by Zero Field Cooled and Field Cooled (ZFC-FC) measurements. The magnetic entropy change is estimated from the magnetisation isotherms taken around the transition temperature and hence identified a potential magnetic refrigerant material near room temperature and lower temperatures.