X-ray diffraction line broadening studies of Raney copper and nickel

Abstract

X-Ray diffraction line broadening analysis has been used to determine crystallite sizes, microstrains and stacking fault probabilities in Raney nickel and Raney copper catalysts prepared by different methods. The data for the Raney catalysts were compared with those for ball-milled copper and nickel powders. Time and temperature of digestion of the Raney alloys affect the defect structures. The crystallite size in the (111) direction was mainly determined by the digestion temperature. On aging a highly active Raney nickel, a rapid decrease of microstrain was observed. This was followed by a steady growth in the (100) direction, while little change occurred in the (111) direction. Aging the catalyst and increasing the digestion time of the Raney alloy were shown to cause similar changes in defect structure. The microstrain and stacking fault probability were observed to be inversely related to crystallite size.