Rapid synthesis of La0.85Na0.15MnO3 by spark plasma sintering: Magnetic behavior and magnetocaloric properties

The La0.85Na0.15MnO3 perovskite has been synthesized in polycrystalline form using the Spark Plasma Sintering technique (SPS). The in-situ reaction proceeds in a few minutes at 800 °C under 50 MPa with the very high heating rate of 100 °C min−1. Rietveld refinement of the X-ray diffraction patterns indicates that our sample is of pure single phase rhombohedral structure (image symmetry). Paramagnetic–ferromagnetic phase transition at TC = 310 K is observed for our studied sample. Magnetic entropy change,image, deduced from isothermal magnetization curves, is about 2.42 J kg K−1 in a magnetic applied field change of 5 T. Although this value is modest, the magnetocaloric effect extends over a large temperature range leading to an important value of the relative cooling power (RCP). The RCP value at 5 T reaches 316.6 J kg−1. This value corresponds to about 77% of that observed in pure Gd.