Effect on electron energy on amorphization of ZrCr2

Abstract

The influence of electron energy on the amorphization of ZrCr2 at 25 K was measured. Amorphization was observed at electron energies from 900 to 330 keV. The dose-to-amorphization increases with decreasing electron energy with two steps, one at 700 keV corresponding to the decrease in the Zr displacement cross section due to the approaching displacement threshold of Zr and one at 500 keV corresponding to an appreciable decrease in the displacement cross section of Cr due to the approaching displacement threshold for Cr. At lower electron energies, it is believed that amorphization occurs principally through a secondary displacement mechanism, where light impurity atoms (mainly O) are displaced by electrons and displace in turn the heavier atoms. By fitting the results using electron displacement cross sections, we find the displacement energies in each sublattice to be EdZr=22 eV, EdCr=23 eV, EdO=4 eV.