CharaDiff

The project entitled “Characterization of defects by Advanced Diffraction techniques to evaluate micro-crystals deformation stages” (CharADiff) aims at gaining a detailed understanding of the mechanics of small scale objects (micro and nano-crystals) by the implementation of an unprecedented combination of recent and specifically-developed in-situ cutting-edge x-ray diffraction techniques: 1) in-situ coherent x-ray diffraction that enables to detect and evaluate the number of lattice defects (dislocations) in small scale crystals during mechanical solicitation; 2) in-situ micro-Laue diffraction that allows for studying the nature and sequence of activated dislocation slip systems during plastic deformation of small objects; 3) post-mortem Bragg ptychography that provides a 3D image of the displacement field caused by lattice defects left in the deformed objects and 4) ptychographic topography, a novel technique developed in this project, to map individual lattice defects while remaining compatible with future in-situ deformation studies. These techniques are applied to a unique system: InSb semi-conductor micro-crystals of initial excellent crystalline quality whose mechanical properties have been already thoroughly studied, therefore being a robust benchmark. The outcomes of this original methodology are two-fold: - developing a tool box combining in-situ and post-mortem advanced diffraction techniques to characterize the deformation response of small scale objects (deformation stages and lattice defects storage): this will enrich the current knowledge on small scale mechanics, providing responses to some of the open questions still remaining in Materials Science on the effects of size reduction; - assessing the complementarity between some of the most recent diffraction techniques developed at synchrotrons with the perspective to push their applicability to the forefront of their current use. Moreover, a new non-destructive imaging technique will be developed, ptychographic topography, with the strong perspective to be implemented within an in-situ setup, as another step forward. The impact of the project is potentially far beyond the frontiers described above, in particular in the field of nanotechnology, where the x-ray diffraction techniques developed here could constitute non-destructive solutions to assess the crystalline quality of small-scale crystals that are the building blocks of miniaturized devices, therefore allowing for quantitative diagnostics and defect engineering. To guarantee the success of this 36 month-project, a well thought consortium of French and Swiss experts has been settled, with strong complementarity in the fields of experimental and simulation approaches, as well as Materials Science and diffraction. A total of 86.4 person-months will be deployed by the consortium, including 9 permanent staffs and 2 post-doctoral fellows.