Structural evolution mechanisms of amorphous and liquid As2Se3 at high pressures

Year: 2016

Authors: Properzi L., Santoro M., Minicucci M., Iesari F., Ciambezi M., Nataf L., Le Godec Y., Irifune T., Baudelet F., Di Cicco A.

Autors Affiliation: Univ Camerino, Sch Sci & Technol, Div Phys, I-62032 Camerino, Italy; Synchrotron Soleil, LOrme Merisiers, F-91192 Gif Sur Yvette, France; Ist Nazl Ottica, CNR, I-50019 Sesto Fiorentino, Italy; European Lab Non Linear Spect LENS, I-50019 Sesto Fiorentino, Italy; Univ Camerino, CNISM, Sch Sci & Technol, Div Phys, I-62032 Camerino, MC, Italy; UPMC, Univ Paris 04, IMPMC, CNRS UMR 7590, F-75005 Paris, France; Ehime Univ, Geodynam Res Ctr, Matsuyama, Ehime 7908577, Japan; Tokyo Inst Technol, Earth Life Sci Inst, Tokyo 1528550, Japan.

Abstract: The elusive structure of compressed, melt-quenched As2Se3 was studied in both its liquid and amorphous form up to 4.4 and 30 GPa, respectively, by means of x-ray absorption spectroscopy and diffraction. The evolution of the short-range structure is studied by As and Se multiple K-edge extended x-ray absorption fine structure (EXAFS) refinement, while changes in intermediate-range ordering are revealed by x-ray diffraction and near-edge structures. In the liquid, at the nearest-neighbor length scales, a gradual disordering and slight elongation of the As-Se average distances is observed, preserving the local coordination upon increasing pressure, whereas substantial compression and disordering are observed at intermediate distances. Similarly, in the amorphous form we found a progressive slight elongation and disordering of the first-neighbor As-Se average distance R (from similar to 2.42 to 2.44 angstrom) and bond variance sigma(2) (from similar to 0.004 to 0.008 angstrom(2)) upon increasing pressures up to 30 GPa. On the other hand, gradual shortening of the second and farther neighbor distances, more evident below 15 GPa, are compatible with data analysis. No sign of crystallization and gradual metallization are observed for amorphous a-As2Se3 up to 30 GPa. The emerging picture for the structure evolution under high pressures is a compaction mechanism involving mainly changes at intermediate distances, weakly affecting the first-neighbor bonding character.

Journal/Review: PHYSICAL REVIEW B

Volume: 93 (21)      Pages from: 214205-1  to: 214205-8

KeyWords: RAY-ABSORPTION SPECTROSCOPY; BODY DISTRIBUTION-FUNCTIONS; SHORT-RANGE STRUCTURE; CONDENSED MATTER; EXAFS; SYSTEM; ORDER; SETUP; SE
DOI: 10.1103/PhysRevB.93.214205

Citations: 17
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