Effect of (Al, Sn) doping on structural, magnetic and magnetocaloric properties of La0.7Ca0.1Pb0.2Mn1−x−yAlxSnyO3 (0 ≤ x,y ≤ 0.075) manganites

The effect of aluminum and tin doping on the microstructure, magnetic and magnetocaloric effects in La0.7Ca0.1Pb0.2Mn1−x−yAlxSnyO3 (0 ≤ x,y ≤ 0.075) manganite compounds has been investigated. All the samples have been elaborated using the conventional sol-gel method. X-ray diffraction (XRD) analysis using Rietveld refinement has shown that all the samples under investigation crystallize in the rhombohedral structure with R3¯ c space group. The magnetic properties of these compounds are discussed in detail, based on magnetization and the inverse of susceptibility, over a wide temperature range (T = 0-350 K). Magnetization measurements versus temperature in a magnetic applied field of 0.05 T showed that all our investigated samples display a paramagnetic-ferromagnetic transition with decreasing temperature. From the measured magnetization data of La0.7Ca0.1Pb0.2Mn1−x−yAlxSnyO3 samples as a function of magnetic applied field, the associated magnetic entropy change |Δ SM | and the relative cooling power RCP have been determined. In the vicinity of TC, |Δ SM | reached, in a magnetic applied field of 5 T, maximum values of 3.7 J/kg K, 2.7 J/kg K 2.3 J/kg K and 2 J/kg K for x, y = 0.0, 0.025, 0.05 and 0.075 respectively.