Intergranular films at Au-sapphire interfaces

The existence of nanometer-thick amorphous equilibrium films at metal-ceramic interfaces has been experimentally verified for the Au–Al2O3 system. The films were formed using a novel experimental approach, in which thin sputtered films of Au were dewetted on a sapphire substrate which was previously...

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Bibliographic Details
Published in:Journal of materials science 2006-12, Vol.41 (23), p.7775-7784
Main Authors: BARAM, Mor, KAPLAN, Wayne D
Format: Article
Language:English
Subjects:
Aluminum oxide
Anorthite
Applied sciences
Building materials. Ceramics. Glasses
Ceramic industries
Cermets
Chemical industry and chemicals
Condensed matter: structure, mechanical and thermal properties
Electron microscopes
Exact sciences and technology
General studies
Glass
Gold
Grain boundaries
Interface structure and roughness
Materials science
Metals. Metallurgy
Physics
Qualitative analysis
Refractivity
Sapphire
Solid surfaces and solid-solid interfaces
Solid-fluid interfaces
Sputtered films
Substrates
Surfaces and interfaces
thin films and whiskers (structure and nonelectronic properties)
Technical ceramics
Thick films
Thin films
Transmission electron microscopy
Van der Waals forces
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Summary:The existence of nanometer-thick amorphous equilibrium films at metal-ceramic interfaces has been experimentally verified for the Au–Al2O3 system. The films were formed using a novel experimental approach, in which thin sputtered films of Au were dewetted on a sapphire substrate which was previously partially wetted with drops of anorthite glass (CaO–2SiO2–Al2O3). High-resolution transmission electron microscopy and qualitative analytical transmission electron microscopy were used to confirm the existence of the amorphous films. In addition, positive and relatively large Hamaker constants were calculated for the Au-film-Al2O3 interface, which indicates the existence of an attractive van der Waals force which stabilizes the film, similar to equilibrium films at grain boundaries in ceramics. A ∼ 1 nm thick surface film was also detected on the (0001) surface of sapphire substrates partially wetted by anorthite glass. The refractive index required to stabilize the surface films, via a positive Hamaker constant, is explored.
ISSN:0022-2461
1573-4803
DOI:10.1007/s10853-006-0897-7