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Grain boundary segregation

Investigation on CIGS twin

JointsChalcoI. Braems

The CuIn1-xGaxSe2 (CIGS) compound is an absorber used in thin-films photovoltaïc cells whose conduction properties strongly depend on its microstructure: interestingly, the polycrystal displays better properties than the monocrystal.
As a complement to experimental studies, we investigated the thermodynamic properties of CIGS twins with respect to the gallium concentration x to validate/invalidate the suggested hypothesis of a grain boundary segregation that would favor conduction.
We observed three possible structures for the most frequently encountered (112)[1-10] twin and showed that segregation was favored for none of them. These computations have been confirmed by a detailed thermodynamic study of the segregation effects (site, alloy and size effects) and have later been confirmed by experimental observations carried out in IMN.

 Keywords: CIGS, interface, segregation

Interface segregation in metals

P. Paillard

In metals and alloys, solute atoms sometimes segregate to interfaces (surfaces, grain boundaries, interphase boundaries). As this alters the interface cohesion, it can result in a dramatic degradation of the material mechanical properties.

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