Evolution of Magnetocaloric Behavior in Oxygen Deficient La2/3Ba1/3MnO3−δ Manganites

Effects of oxygen deficiency on the thermomagnetic properties of La2/3Ba1/3MnO3−δ polycrystalline perovskites have been predicted. By the help of the phenomenological model, the temperature dependences of the magnetization for La2/3Ba1/3MnO3−δ with δ=0.0, 0.02, 0.05, 0.08, and 0.1 upon 1 T magnetic field were simulated. The behavior of the temperature dependent magnetocaloric effect, in the vicinity of magnetic phase transitions, was investigated. The magnetic entropy change, specific heat, and adiabatic temperature change for several δ were obtained. The values of maximum magnetic entropy change, full-width at half-maximum, and relative cooling power, in 1 T magnetic field variation, were calculated. As the oxygen content increases, the magnetocaloric effect of La2/3Ba1/3MnO3−δ, decreases and shifts to room temperature. The results obtained show a strong dependence on the oxygen deficiency of the materials. The magnetocaloric effect of these materials is large and tunable, suggesting a possible technical application of the materials at moderate magnetic fields near room temperature. It is shown that for La2/3Ba1/3MnO3−δ, the magnetic entropy change and adiabatic temperature change follows a master curve behavior.