Synthesis of Different-Sized La0.7Sr0.3MnO3 Nanoparticles via a Polyacrylamide Gel Route and Their Magnetocaloric Properties

In this work, a polyacrylamide gel route was used to synthesize La0.7Sr0.3MnO3 nanoparticles. It is shown that single-phase La0.7Sr0.3MnO3 nanoparticles with a rhombohedral perovskite structure can be prepared at a calcination temperature of 600 A degrees C when separately using citric acid, tartaric acid, acetic acid, oxalic acid, and EDTA as the chelating agent. The particles prepared using the five chelating agents are nearly spherical in shape with a narrow diameter distribution, and have an average size of 24, 28, 36, 38, and 50 nm, respectively. Magnetic properties of the 24 and 50 nm samples (termed as samples S1 and S5, respectively) were investigated. It is revealed that the samples have a similar ferromagnetic Curie temperature T (C) , and exhibit a typical second-order magnetic phase transition near T (C) . The maximum magnetic entropy change at an applied magnetic field of 15 kOe is obtained to be about 0.71 and 0.74 J kg(-1) K-1 for the 24 and 50 nm samples, respectively.