Ion Exchange at Metal–Ceramic Interfaces
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Objectives: • To study diffusion reactions at planar aluminum-spinel (Al–MgAl 2 O 4 ) interfaces. PowerPoint PPT Presentation


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Ion Exchange at Metal–Ceramic Interfaces F. Ernst, 1 R. Raj 2 1 Case Western Reserve University, 2 University of Colorado at Boulder DMR-0208008. Objectives: • To study diffusion reactions at planar aluminum-spinel (Al–MgAl 2 O 4 ) interfaces.

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Objectives: • To study diffusion reactions at planar aluminum-spinel (Al–MgAl 2 O 4 ) interfaces.

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Objectives to study diffusion reactions at planar aluminum spinel al mgal 2 o 4 interfaces

Ion Exchange at Metal–Ceramic InterfacesF. Ernst,1 R. Raj21Case Western Reserve University, 2University of Colorado at BoulderDMR-0208008

Objectives:

• To study diffusion reactions at planar aluminum-spinel (Al–MgAl2O4) interfaces.

• To investigate the effect of an external electric field on diffusion reactions at such interfaces.

Right: High-resolution TEM image revealing the interface structure of an as-grown Al–MgAl2O4.

Al film

MgAl2O4

Result:

Tempering aluminum–spinel interfaces in applied electric fields, we found credible evidence that diffusion reactions of magnesium, aluminum, and oxygen ions can be controlled by the strength and polarity of applied electric fields. Positive ions were more mobile than negative ions in a spinel under the influence of applied electric fields. Differences in mobility and valency of constituent ions suggest a correlation between interdiffusion and electrical fields, which is conceptually consistent with the electrostatic model of mechanical adhesion.

2 nm

Al film

MgAl2O4

Mg-deficient reaction layer

O

Al3+

Al

Right: Composition profiles show the different response (diffusion) of ions across the interface when annealing in an external electric field.

Mg2+

Mg


Objectives to study diffusion reactions at planar aluminum spinel al mgal 2 o 4 interfaces

Education and Outreach

On January 14 and 21, 2005, the team at Case invited students of the Ruffing Montessori middle school in Cleveland Heights for two lectures on "Materials and Microscopy" and a hands-on demonstration of scanning electron microscopy and transmission electron microscopy. (http://www.ruffingeast.org/webpages/middle_school.htm)

Jeremy Mark, an undergraduate student performed his senior project in relation to this project.

Gurpreet Singh, graduate student at UCB, was trained in UHV techniques, thin-film preparation, and mechanical testing of thin films.

Yeonseo Yu, graduate student at Case completed his Ph.D. degree in August 2005. His Ph.D. thesis is based on the work on this project.

Broader Impacts

The latest results of this project are going to be presented at the 2006 TMS Annual Meeting & Exhibition.

A journal article about the effects of annealing under applied electric fields is in preparation.

Ion Exchange at Metal–Ceramic InterfacesF. Ernst,1 R. Raj21Case Western Reserve University, 2University of Colorado at BoulderDMR-0208008


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