Prediction of magnetic and magnetocaloric properties in Pr$_{0.8−x}$Bi$_x$Sr$_{0.2}$MnO$_3$ ($x = 0$, 0.05 and 0.1) manganites

[摘要] In this work, we have investigated the magnetic and magnetocaloric properties of Pr$_{0.8−x}$Bi$_x$Sr$_{0.2}$MnO$_3$ ($x = 0$, 0.05 and 0.1) polycrystalline manganites prepared by sol–gel route on the basis of a phenomenological model. Temperature dependence of magnetization indicates that all our samples exhibit a second order paramagnetic to ferromagnetic transition with a decrease in temperature. A correlation between experimental results and theoretical analysis based on a phenomenological model is investigated. The magnetic and magnetocaloric measurements are well simulated by this model. Under a magnetic applied field of 5 T, the theoretical absolute values of the maximum of magnetic entropy change $\Delta S_{\rm Max}$ are found to be equal to 5.33, 3.33 and 2.97 J kg$^{−1} K$^{−1}$ for $x = 0$, 0.05 and 0.1 respectively. The relative cooling power and the specific heat capacity values are also estimated. The predicted results permit us to conclude that our compounds may be promising candidates for magnetic refrigeration at low temperatures.

[学科分类] 材料工程

[关键词] Magnetic transition;phenomenological model;magnetocaloric effect;critical exponents;specific heat.