Magnetic properties, Mossbauer and aftereffect studies of Pr10Fe90-xBx (x=5.88-11.5) nanocomposites

Magnetic properties, phase evolution and aftereffect of melt-spun Pr10Fe90-xBx (x=5.88-11.5) nanocomposite ribbons have been studied. Summarizing the results of thermal magnetic analysis and Mossbauer spectroscopy, two phases, namely Pr2Fe14B and alpha-Fe, were found for ribbons with x=5.88 and 7.5, while additional two metastable phases, Pr2Fe23B3 and Fe3B, prevailed for x=9. For x=10 and 11.5, only three of these phases: Pr2Fe14B, Pr2Fe23B3, and Fe3B, but not alpha-Fe were present. The optimal magnetic properties of B-r=10.1 kG, H-i(c)=6.4 kOe, and (BH)(max)=16.1 MGOe were achieved in the Pr10Fe84.12B5.88 ribbon, while H-i(c) 8.71 kOe and (BH)(max) 14.7 MGOe were obtained in Pr10Fe80B10. Furthermore, Pr10Fe78.5B11.5 having the optimal H-i(c) (9.33 kOe) exhibited minimum values in activation volume V=5.03x10(-19) cm(3), because it possessed the least volume fraction of the magnetically soft phases. Finally, confirmation of the absence of spin reorientation in Pr2Fe14B down to 5 K assures its advantage over Nd2Fe14B for low-temperature applications. (C) 2003 American Institute of Physics.