Magnetocaloric properties in Ln_0.67Ba_0.33Mn_1_xFe_xO_3 (Ln = La or Pr) manganites

摘要

We have investigated the magnetocaloric properties of Ln_0.67Ba_0.33Mn_1_xFe_xO_3 (Ln = La or Pr) manganites with x = 0 and 0.05. All compounds present a maximum and large magnetocaloric effect near the Curie temperature (Tc). The associated maximum value of the magnetic entropy change, at 5 T applied change in the magnetic field, is 4.37J.kg~-1K~-1 for Pr_0.67Ba_0.33MnO_3 manganite with a T_c value of 205 K. The corresponding relative cooling power (RCP) reaches 230J.kg~-1. All the samples present similar RCP values that are relatively high and are promising materials to be used in ecologically friendly magnetic refrigeration technology. Iron doping reduces both T_c and △SMmax and spreads the temperature working range with an almost constant RCP and can then be used to tune the working conditions of a refrigerator device.