Influence of iron substitution on the ferromagnetic ordering and magnetic entropy variation in La1-xNaxMn1-yFeyO3 (x = 0.1, 0.2 and y = 0, 0.1)

Abstract

In the present work, the magnetocaloric effect of La1-xNaxMn1-yFeyO3 (x = 0.1, 0.2 and y = 0, 0.1) was investigated using magnetic characterization data. The X-ray diffraction confirms that all samples synthesized by flash combustion and calcined at 1000 °C have been crystallized in a rhombohedral structure with an R3¯c space group. According to the magnetization versus temperature results, LaMnO3 is a ferromagnetic material with a Curie temperature TC = 95 K. The substitution of the rare earth La by alkali magnetic metal Na leads to an increase of TC to 265 and 330 K accompanied with large magnetic entropy change/-ΔSMmax/ of 2.88 and 4.88 J.Kg-1K−1 for x = 0.1, 0.2, respectively. The addition of 10% of Fe in La1-xNaxMn1-yFeyO3 decreases the Curie temperature and the magnetic entropy change, while, the relative cooling efficiency increases. The Mössbauer spectrum recorded at room temperature represents a paramagnetic character of the manganites and proves the distribution of Fe3+ in the samples.