Effect of doping concentration and heat treatment on the refrigerant capacity of Pr_0.63Dy_0.37-xSr_xMnO₃

Based on the evolution of the quantity of Sr in Pr_0.63Dy_0.37-xSr_xMnO₃ (x = 0.00 and x = 0.30) systems and the different heat treatments (500, 800 and 1300 °C), various physical changes are illustrated by these samples. X-ray diffraction patterns were carried out revealing that the heat temperature can affect the structure of the systems. Zero-Field-Cooled and Field-Cooled magnetizations revealed the appearance of different magnetic transitions; from the paramagnetic state to the antiferromagnetic one. Once increasing the temperature of heat up to 1300 °C and for x = 0.30, the system presents a ferromagnetic order at Curie temperature that is around 200 K. Magnetic hysteresis loops confirm the transitions presented by the magnetic measurements. The heating temperature affected also the evolution of the magnetic entropy change. All samples show an important increase in the data values of the maximum of the magnetic entropy change while augmenting the applied magnetic field. We note an important result that is the refrigerant capacity of the x = 0.30 sample heated at 1300 °C is 725% compared to that at 500 °C.