The characterization of amorphous Al/sub 2/O/sub 3/ by Extended Energy Loss Fine Structure (EXELFS) analysis
Conference
·
OSTI ID:7171558
Recently an investigation of the effects of ion implantation on the microstructure and properties of Al/sub 2/O/sub 3/ has revealed differences in the response of various forms of amorphous Al/sub 2/O/sub 3/ to post-implantation annealing. Specifically the amorphous implanted layer in a specimen implanted with a stoichiometric ratio of aluminum and oxygen at -185/degree/C (Al/sub 2/O/sub 3/-Al,O) recrystallized into a dual phase microstructure consisting of ..gamma..-Al/sub 2/O/sub 3/ and ..cap alpha..-Al/sub 2/O/sub 3/. In contrast the amorphous layer in a specimen implanted with iron at -185/degree/C (Al/sub 2/O/sub 3/-Fe) recrystallized completely to epitaxial ..cap alpha..-Al/sub 2/O/sub 3/. In order to understand these differences EXELFS analysis has been performed on several types of Al/sub 2/O/sub 3/ including Al/sub 2/O/sub 3/-Al,O and Al/sub 2/O/sub 3/-Fe, as well as single crystal ..cap alpha..-Al/sub 2/O/sub 3/ and crystalline ..gamma..-Al/sub 2/O/sub 3/. Disko, Bourdillon, and Sevely have also reported EXELFS studies of Al/sub 2/O/sub 3/. All measurements were made on backthinned specimens prepared using established procedures. Comparison of the results revealed several differences. The Al-O interatomic distances measured in the two forms of amorphous Al/sub 2/O/sub 3/ differed by /approximately/0.01 nm., regardless of which edge was used for the analysis. Moreover the value measured for Al/sub 2/O/sub 3/-Al,O agrees with the value measured for crystalline ..gamma..-Al/sub 2/O/sub 3/, the form into which it recrystallizes. In a similar way the Al-O distance measured in the amorphous Al/sub 2/O/sub 3/-Fe agrees with the value measured for crystalline ..cap alpha..-Al/sub 2/O/sub 3/, the form into which it recrystallizes. Investigation of the relationship between these underlying structural differences and recrystallization behavior is continuing. 7 refs., 3 figs.
- Research Organization:
- Oak Ridge National Lab., TN (USA)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 7171558
- Report Number(s):
- CONF-880841-6; ON: DE88007484
- Country of Publication:
- United States
- Language:
- English
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