Magnetic properties and magnetocaloric effects in NaZn13-type La(Fe, Al)13-based compounds

摘要

In this article,our recent progress concerning the effects of atomic substitution,magnetic field,and temperature on the magnetic and magnetocaloric properties of the LaFe13-xAlx compounds are reviewed.With an increase of the aluminum content,the compounds exhibit successively an antiferromagnetic (AFM) state,a ferromagnetic (FM) state,and a mictomagnetic state.Furthermore,the AFM coupling of LaFe13-xAlx can be converted to an FM one by substituting Si for Al,Co for Fe,and magnetic rare-earth R for La,or introducing interstitial C or H atoms.However,low doping levels lead to FM clusters embedded in an AFM matrix,and the resultant compounds can undergo,under appropriate applied fields,first an AFM-FM and then an FM-AFM phase transition while heated,with significant magnetic relaxation in the vicinity of the transition temperature.The Curie temperature of LaFe13-xAlx can be shifted to room temperature by choosing appropriate contents of Co,C,or H,and a strong magnetocaloric effect can be obtained around the transition temperature.For example,for the LaFe11.5Al1.5C0.2H1.0 compound,the maximal entropy change reaches 13.8 J·kg-1·K-1 for a field change of 0-5 T,occurring around room temperature.It is 42％ higher than that of Gd,and therefore,this compound is a promising room-temperature magnetic refrigerant.