STRUCTURE AND GROWTH OF BERYLLIUM OXIDE ON SINGLE CRYSTALS OF BERYLLIUM
The nature of the structure and growth of BeO films formed by heating single crystals of beryllium in air over a wide range of temperatures was studied in detail using electron diffraction, and electron microscopy. The epitaxial nature of the oxide formed in the temperature range 300 deg C to 400 deg C on a Be (001) cleavage face was established. In the case of electropolished (001) surfaces of beryllium, it was found that the epitaxial BeO overgrowth was less well-defined. It was suggested that this disorientation was due to the formation, during the electropolishing procedure, of surface elements other than (001) upon which the oxide could grow. Onedegree (103)-oriented BeO was observed on (100) and (110) faces of Be. The oxidation rate increased with increase in temperature, resulting in a corresponding increase in the proportion of randomly-oriented BeO until, above 600 deg C, only random growth was observed in the upper regions of the layer. At about 800 deg C, a pronounced (001) habit of the randomly-oriented BeO crystals was developed. The diameter of the oxide crystals was estimated from the diffraction patterns to be some tens of Angstroms below 300 deg C, and in the order of thousands of Angstroms at about 800 deg C. The non-protective nature of the oxide layer formed at 600 deg C and above, is evident from the electron micrographs which showed the development of projecting needles of BeO up to 5 mu in length and several hundred Angstroms in thickness. The needles possessed a (110) axis, and possibly grew around screw dislocations. Thin BeO flakes up to several mu in dianneter were also observed in this temperature range, the diffraction pattern indicating considerable distortion of the flake. (auth)
- Research Organization:
- Imperial Coll. of Science and Tech., London
- NSA Number:
- NSA-13-009016
- OSTI ID:
- 4267291
- Journal Information:
- Acta Cryst., Journal Name: Acta Cryst. Vol. Vol: 12
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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