What is it about?
The pressure dependent structure of the prototypical network-forming chalcogenide glass GeSe2 was investigated by neutron diffraction and first-principles molecular dynamics. In the experimental work, site-specific experimental information was provided by using neutron diffraction with isotope substitution at pressures up to 8.2 GPa.
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Why is it important?
The results show pressure-driven changes that differ substantially from those observed in common oxide glasses such as SiO2 and GeO2. Edge-sharing tetrahedra persist as important structural motifs until a threshold pressure of about 8.5 GPa is attained, whereupon a mediating role is found for homopolar (like atom) bonds in the appearance of higher coordinated Ge-centered polyhedra. The observed mechanisms of network change are likely to be generic for other glass-forming materials where homopolar bonds and fragility-promoting edge-sharing motifs are prevalent in the ambient-pressure structure.
Perspectives
Blowouts led to some challenges in the high-pressure diffraction work!
Professor Philip S Salmon
University of Bath
Read the Original
This page is a summary of: Density-driven defect-mediated network collapse of GeSe 2 glass , Physical Review B, August 2014, American Physical Society (APS),
DOI: 10.1103/physrevb.90.054206.
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