Abstract

Magnetocaloric effect in sol-gel derived La<inf>0.75-x</inf>Gd<inf>x</inf>Sr<inf>0.25</inf>MnO<inf>3</inf> was studied as a function of temperature and magnetic field. The crystallite size of the rhombohedral manganites was increased and the magnetisation was decreased with increasing Gd doping from x = 0-0.3. By using the indirect measurement, the entropy change computed from temperaturedependent magnetisation was proportional to the applied DC magnetic field. Under the field of 0.7 T, the maximum entropy changes of 0.93-1.14 J/kg·K were observed around the Curie temperature (T<inf>C</inf>) determined by AC magnetic susceptometry. The T<inf>C</inf> was decreased with the increase in x. The maximum magnetocaloric effect occured in the sample with x = 0.15 and it could be used in magnetic refrigeration near the room temperature.