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Ca segregation to basal surface in Alpha-alumina

Kaplan, Wayne D. and Müllejans, H. and Rühle, M. and Rödel, Jürgen and Claussen, Nils (1995):
Ca segregation to basal surface in Alpha-alumina.
In: Journal of the American Ceramical Society. 78 (1995), No. 10, S. 2841-2844, pp. 2841-2844, 78, (10), [Online-Edition: http://dx.doi.org/10.1111/j.1151-2916.1995.tb08064.x],
[Article]

Abstract

High-resolution transmission electron microscopy (HRTEM) and analytical electron microscopy (AEM) mere used to investigate the structure and chemistry of (0001) alpha-Al2O3/Al interfaces in melt-infiltrated polycrystalline alumina composites, HRTEM revealed an interfacial region different from both Al and alpha-Al2O3, with a structural width of 0.8 +/- 0.2 nm, AEM of the same interfaces revealed a Ca excess of Gamma = 2.5 +/- 0.5 Ca atoms per nm(2) (Ca/nm(2)). AEM of a basal twin boundary in the alpha-Al2O3 also revealed a Ca excess (Gamma = 1.0 +/- 0.5 Ca/nm(2)). Since the metal-ceramic interfaces mere the free surfaces of pores before melt infiltration, it can be concluded that Ca segregates to the basal surface of alumina, as well as to basal twin boundaries. Furthermore, the Ca at the free surfaces does not reside on only one cation plane, but is spread over 4 +/- 1 basal cation layers and forms an interfacial phase with a nominal composition of CaO . 6Al(2)O(3).

Item Type: Article
Erschienen: 1995
Creators: Kaplan, Wayne D. and Müllejans, H. and Rühle, M. and Rödel, Jürgen and Claussen, Nils
Title: Ca segregation to basal surface in Alpha-alumina
Language: English
Abstract:

High-resolution transmission electron microscopy (HRTEM) and analytical electron microscopy (AEM) mere used to investigate the structure and chemistry of (0001) alpha-Al2O3/Al interfaces in melt-infiltrated polycrystalline alumina composites, HRTEM revealed an interfacial region different from both Al and alpha-Al2O3, with a structural width of 0.8 +/- 0.2 nm, AEM of the same interfaces revealed a Ca excess of Gamma = 2.5 +/- 0.5 Ca atoms per nm(2) (Ca/nm(2)). AEM of a basal twin boundary in the alpha-Al2O3 also revealed a Ca excess (Gamma = 1.0 +/- 0.5 Ca/nm(2)). Since the metal-ceramic interfaces mere the free surfaces of pores before melt infiltration, it can be concluded that Ca segregates to the basal surface of alumina, as well as to basal twin boundaries. Furthermore, the Ca at the free surfaces does not reside on only one cation plane, but is spread over 4 +/- 1 basal cation layers and forms an interfacial phase with a nominal composition of CaO . 6Al(2)O(3).

Journal or Publication Title: Journal of the American Ceramical Society. 78 (1995), No. 10, S. 2841-2844
Volume: 78
Number: 10
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Nonmetallic-Inorganic Materials
11 Department of Materials and Earth Sciences > Fachbereich Materialwissenschaft (1999 aufgegangen in 11 Fachbereich Material- und Geowissenschaften)
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 19 Nov 2008 15:58
Official URL: http://dx.doi.org/10.1111/j.1151-2916.1995.tb08064.x
Identification Number: doi:10.1111/j.1151-2916.1995.tb08064.x
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