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L'Association Européenne de Cristallographie (ECA) organise depuis 2021 des "webinaires déjeuner". Les groupes d'intérêt spéciaux (SIG) et les groupes d'intérêt général (GIG) de l'ECA organisent à tour de rôle un webinaire adapté à la communauté des cristallographes au sens large. Le 22ième webinaire sera diffusé le jeudi 29 juin 2023 à 13h:  A key purpose of high-pressure research - effect of pressure on structures and functionalities of materials par  Martina Vrankić  (Ruđer Bošković Institute, Zagreb, Croatie). Inscriptions ici.

The properties of inorganic and hybrid organic-inorganic materials under high pressure can be of practical importance in the manufacture and durability of devices. In particular, the powder X-ray diffraction and structural evolution under pressures from synchrotron radiation experiments, in a separate manner are raised for the selected inorganic and hybrid inorganic- organic materials to emphasize the need for this characterization method, without which it would be impossible to correlate structural and delicate physical and photophysical behavior. The inorganic materials with high bulk moduli (above 100 GPa) contrast with the more soft hybrid organic-inorganic materials, which usually, have bulk moduli between 10 and 20 GPa. The physical and chemical features of tuned, shape-selected ZnO particles are discussed in terms of response to external hydrostatic pressure using the synchrotron powder X-ray diffraction measurements and X-ray photoelectron spectroscopy fingerprints, latter giving an insight into the morphological versatility and surface diversity of ZnO powder. This talk will comparatively show that the diversity of size and shape of ZnO particles distinguishes the wurtzite-to-rocksalt transformation reversibility phenomena by dictating the microstructure-dependent deformation behavior and ultimately leads to different microstrain responses to hydrostatic pressure. In addition, an application of pressure to hybrid materials that are relatively soft can induce reversible, irreversible, insulator-to-metal, crystalline-to-amorphous, and piezochromic transitions that can lead to metallization and narrowing of the band gap. Exploring materials with useful properties that can be preserved under ambient conditions for application is one of the main goals of high-pressure research.


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