HREM Observations of Deformation Recovery on and Near Surfaces of Eu2O3

Abstract

Profile imaging technigue has been achieved very much in the field of surface science since it was first proposed. This work will show the deformation recovery on and near the surfaces of Eu2O3 under electron irradiation. The experiment was carried out in a JEOL-200CX high-resolution electron microscope. The Eu2O3 phase has a complex cubic structure with a=1.087 nm. A projected unit cell has been marked in Fig. la. It has been indicated that only Eu3+ ions , which are located in f.c.c. sublattice, appeared in HR images under certain defocus and in the thin areas of specimen. The structural character of Eu2O3 shown by HR images may be analyzed based upon comparing with that of simple f.c.c. structure.It can be seen from Fig. la that the surfaces of Eu2O3 are clean and Eu3+ ions on the (111) surfaces S1 and S2 moved /12 towards to the right (it is actually surface stacking fault). In Fig.lb the stacking fault on S2 was removed under electron irradiation but remained on S1. The stacking fault energy of Eu2O3 is high in the bulk. From Fig.l it can be known that the stacking fault energy may become lower on the (111) surface due to less constrained factors there. This kind of surface stacking fault is related to surface partial dislocations, and both of them may act as the main forms of surface deformation under electron irradiation.