Investigation on physical properties in lanthanum vacancy of La0.65Ca0.35MnO3 elaborated at high temperature

Abstract

The lanthanum deficient La0.65−x□xCa0.35MnO3 (0 ≤ x ≤ 0.12) have been elaborated by the solid-state reaction at high temperatures. All samples have been studied by several techniques including X-ray diffraction, scanning electron microscopy (SEM), spectrum two FT-IR Spectrometer and vibrating sample magnetometer. Rietveld refinement shows that all samples crystallize in the orthorhombic structure with Pbnm space group and that lanthanum deficiency leads to a decrease of the unit cell volume. Magnetization measurements versus temperature exhibit a large ferromagnetic-paramagnetic transition with decreasing temperature. The TC decreases from 270 K for x = 0 to 254 K for x = 0.12. A large magnetic entropy change associated with the ferromagnetic-paramagnetic transition has been observed. The maximum of the magnetic entropy change ΔSMMax decreases from 5 Jkg−1K−1 for x = 0 2.1 Jkg−1K−1 for x = 0.12. Moreover, the maximum magnetic entropy change exhibits a linear dependence with applied magnetic field. The relative cooling power (RCP) decreases from 214 J/Kg for x = 0 to 106 J/Kg for x = 0.12 under an applied magnetic field of 5 T.