MAGNETIC-PROPERTIES OF THE LANI5-H SYSTEM

We simultaneously measured the H/M atomic ratio and the magnetization, M, of LaNi5-H while it was activated and then cycled many times, at 1 00 degrees C and then 26 degrees C. The overall magnetization of the s ample rose steadily as cycling precipitated Ni. In addition, however, M exhibits a large degree of magnetic hysteresis between the absorptio n and desorption isotherms. The magnetization in both the pure alpha a nd beta phases is very sensitive to the H concentration. Furthermore, we found that the intrusion of the intermediate gamma phase, LaNi5Happ roximate to 3, also profoundly altered the magnetic properties of the sample. It is proposed that the ferromagnetism occurs by exchange betw een clusters of fee Ni spins, via polarization of the conduction elect rons.