Effects of heat treatment on crystal structure and magnetic properties of LaFe_12−xAl_xMn compounds

Abstract

Thc LaFel~-.Al,.Mn (r: = 2, 3, 4, 5, 6, 7) alloys have been annealed at different temperatures and for different periods. The crystal structures and magnetic properties of these compounds are investigated by X-ray diffraction and ac susceptibility measurements. The results indicate that the NaZnl3-type structure is slightly sensitive to Mn-doping. However, the rnagnctic properties of thesc compounds are strongly related to the annealing temperature and period. A structural transition occurs in LaFesA17Mn after annealing at 773 K for about three months. A magnetic transition from ferromagnetic to paramagnetic state is found in LaFe7AlsMn after annealing at, 773 K for two months.I )