Fundamental research using synchrotron X-rays on key technological materials

While writing this HDR manuscript, I took the opportunity to look back on my professional carrier to realise I had conducted numerous studies of fundamental research using different synchrotron techniques. I think I am fundamentally curious and therefore I like to discover new or emerging fields of research since it challenges my understanding and possesses a large exploration aspect. As a consequence, I am not a specialist dedicated to one field of research but I develop collaboration with various groups: I've been working on a wide range of research fields, each research field being linked to the problematic of the group I develop collaboration with. And looking back on those years, I noticed that in my collaborations, my contribution was always to provide understanding of key technological material under development, hence the title of this manuscript. Despite it will not be fully developed in this manuscript, there was also a very nice engineering aspect to my career since I have significantly contributed to the construction of two French beamlines at ESRF. From 1999 to 2003, I help built the forth French CRG beamline at ESRF named BM30B-FAME (French Absorption spectroscopy beamline in Material and Environmental sciences) with the complete definition of required beamline characteristics for EXAFS studies on diluted systems (<10 ppm), as well as its components tuning once operational. From 2004 to 2012, I help refurbish the historical first French CRG beamline at ESRF BM32-IF (Interface) with full re-definition and construction of all beamline optical elements as well as the development of the first European white beam (4-40 keV) of submicronic size and its dedicated μLaue station for which I will give some details.Thanks to these two beamlines, I was able to become competent in two emblematic synchrotron techniques that are EXAFS and white beam Laue microdiffraction. Emblematic since they require a continuously adjustable and very bright X-ray energy on a very broad energy range, a challenge only synchrotron may take up. Among all my collaborations, two of them were really long-term collaborations and I choose to present them with some details. The first long-term collaboration is the object of chapter 'Phase-change materials', was dedicated to the study of phase-change materials, covers the 1999-2012 period and makes extensive use of the EXAFS technique. The second long-term collaboration is presented chapter 'High-performance IR detection', is dedicated to IR material, covers the 2006-2018 period, is still ongoing and makes extensive use of the white beam Laue microdiffraction detailed into part 'The μLaue setup'. And finally, because research appears to me as an exciting never-ending journey into wonderland, I will expose in part 'V-Research perspectives' some of my research perspectives.