Surface structural rearrangement of amorphous Fe90Zr10 and Fe83B17 alloy powder by pulverization

Abstract

Several studies have revealed that the amorphous metal alloys are useful materials for use as catalysts [1-3]. The amorphous alloys used in these studies have been prepared by the rapid quenching method [4] in the shape of ribbons, but the small surface area of a ribbon has been a barrier to the development of an alloy with high catalytic activity. We have previously reported that the amorphous ribbon can be finely pulverized using a vibratory rod mill and that the powder retains the amorphous structure [5, 6]. The catalytic activity of the alloy increased upon pulverization, but the increase in the activity could not be explained solely by the increase in surface area. The pulverization brought about not only an increase in the surface area and the surface concentration of active sites, but also a change in catalytic property. The turnover-frequency (TF), which shows the catalytic activity per surface active sites was greater and the effect of the treatment with oxygen and hydrogen was more remarkable with pulverized alloy than those observed with ribbon. These results suggested that pulverization brought about structural modification of the alloy. However, X-ray diffraction analysis (XRD) indicated no change of patterns upon pulverization and suggested no structural modification in the long range. M6ssbauer spectroscopy has been increasingly used