Effect of Co substitution on magnetocaloric effect in La0.67Pb0.33Mn1−xCoxO3 (0.15 ≤ x ≤ 0.3)

The series of cobaltite substituted manganese La0.67Pb0.33Mn1−xCoxO3 has been studied and show the effect of cobaltite substitution. The magnetic and magnetocaloric properties of polycrystalline perovskite were investigated. From the measured magnetization data of the samples as a function of magnetic applied field, the associated magnetic entropy change close to their respective Curie temperature TC and the relative cooling power (RCP) have been determined. The Curie temperature has been analyzed by two methods: a linear extrapolation of M(T) to zero magnetization, and the thermodynamic model. It was found that the maximum change in magnetic entropy for La0.67Pb0.33Mn0.7Co0.3O3 sample reached 3.22 J/kg K at TC = 260 K for a magnetic field of 10 kOe and RCP = 63 J/kg. In view of these results the La0.67Pb0.33Mn1−xCoxO3 compounds are strongly recommended to use as an active magnetic refrigerators.

Research highlights▶ We present hear, the results of an investigation of the magnetocaloric effect in La0.67Pb0.33Mn1−xCoxO3 materials. A large magnetic entropy at the Curie temperature has been observed even though the spin–lattice coupling is been reduced in present system. The Curie temperature TC decreases from 297 K (x = 0.15) to 260 K (x = 0.3). This decrease is accompanied by an increase of the magnetic entropy change. La0.67Pb0.33Mn0.7Co0.3O3 exhibits the highest value of 3.22 J/(K kg) for |ΔSMmax| at the Curie temperature of 260 K, upon 10 kOe applied field variation. The refrigerant capacity (QM) as well as the relative cooling power (RCP) of these compounds increases with Co-doping. Our results suggest that the polycrystalline La0.67Pb0.33Mn1−xCoxO3 have some appropriate properties for a good candidate as a working material for active magnetic refrigerant.