Study of Erbium Thin Film Oxidation in the Electron Microscope

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Abstract
This paper describes the formation of suspect ErO single crystals during erbium evaporation onto NaCl in ultrahigh vacuum (10−8 Torr); and a unique twinning phenomenon in these f.c.c. NaCl‐type crystals (a = 5.12 Å) is observed by electron microscopy. The oxidation of thin erbium foils (650 Å thickness) directly within the electron microscope by double condenser beam heating of selected areas and the sequential recrystallization and growth of the completely oxidized erbium (Er2O3) are investigated. It is shown that the Er2O3 films have a b.c.c. structural characteristic with the unit cell defined by a vacancy defect CaF2 structure composition possessing the T5 (I213) space group for a = 10.55 Å. Er oxidation in the electron microscope at a background pressure of roughly 10−4 Torr appeared to be logarithmic, and presumably lattice diffusion controlled.