These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


PUBMED FOR HANDHELDS

Search MEDLINE/PubMed


  • Title: Revisiting local structural changes in GeO2 glass at high pressure.
    Author: Dong J, Yao H, Guo Z, Jia Q, Wang Y, An P, Gong Y, Liang Y, Chen D.
    Journal: J Phys Condens Matter; 2017 Nov 22; 29(46):465401. PubMed ID: 29053477.
    Abstract:
    Despite the great importance in fundamental and industrial fields, understanding structural changes for pressure-induced polyamorphism in network-forming glasses remains a formidable challenge. Here, we revisited the local structural transformations in GeO2 glass up to 54 GPa using x-ray absorption fine structure (XAFS) spectroscopy via a combination diamond anvil cell and polycapillary half-lens. Three polyamorphic transitions can be clearly identified by XAFS structure refinement. First, a progressive increase of the nearest Ge-O distance and bond disorder to a maximum at ~5-16 GPa, in the same pressure region of previously observed tetrahedral-octahedral transformation. Second, a marked decrease of the nearest Ge-O distance at ~16-22.6 GPa but a slight increase at ~22.6-32.7 GPa, with a concomitant decrease of bond disorder. This stage can be related to a second-order-like transition from less dense to dense octahedral glass. Third, another decrease in the nearest Ge-O distance at ~32.7-41.4 GPa but a slight increase up to 54 GPa, synchronized with a gradual increase of bond disorder. This stage provides strong evidence for ultrahigh-pressure polyamorphism with coordination number  >6. Furthermore, cooperative modification is observed in more distant shells. Those results provide a unified local structural picture for elucidating the polyamorphic transitions and densification process in GeO2 glass.
    [Abstract] [Full Text] [Related] [New Search]