Structural, magnetic properties and magnetocaloric effect of Mn1.2Fe0.8P1−Si B0.03 compounds

Structural, magnetic, and magnetocaloric properties of the MnFePSiB(x = 0.4, 0.5 and 0.55) phases have been investigated. The experimental results show that the critical behavior of the paramagnetic to ferromagnetic phase transition can be tuned through the P/Si ratio. An increase in the Si concentration not only raises the Curie temperature from 176 K to 280 K, but also changes the nature of the magnetic transition from the first order (for x = 0.4) to the second order (for x = 0.55) and, thereby, affects the magnetocaloric properties. The peak values of the thermal hysteresis and magnetic entropy change for a magnetic field change of 0-2T are 10 K, 4 K, 0.8 K and -16.3, -8.7, -5.6 J kg K for x = 0.4, 0.5, and 0.55, respectively. Mechanisms for the magnetic hysteresis loss and possibilities for the room-temperature magnetic refrigeration are discussed.