材料期刊网

A giant magnetocaloric effect was observed at room temperature in Mn(1-x)Cr(x)As compounds with x=0.006 and 0.01. The Cr dopant reduces (or even eliminates) the large thermal hysteresis of MnAs, while it lowers the first-order transition temperature from 313 K for MnAs to 265 K for Mn(0.99)Cr(0.01)As. Near the Curie temperature, a magnetic field induces a first-order phase transition from a ferromagnetic hexagonal phase to a paramagnetic orthorhombic phase, leading to a maximum value of Delta S(M) of 20.2 J/kg K at 267 K for a 5 T field change for Mn(0.99)Cr(0.01)As. The study on the Mn(1-x)Cr(x)As system may open an important field in searching proper materials for room-temperature magnetic refrigeration. (C) 2008 American Institute of Physics.