The elusive structure of compressed, melt-quenched As 2 Se 3 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 ̊ 2 ) upon increasing pressures up to 30 GPa. ̊ and bond variance σ 2 (from ∼0.004 to 0.008 A ∼2.42 to 2.44 A) 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-As 2 Se 3 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.

Structural evolution mechanisms of amorphous and liquid As2Se3 at high pressures

PROPERZI, LEONARDO;MINICUCCI, Marco;IESARI, FABIO;CIAMBEZI, MATTEO;DI CICCO, Andrea
2016-01-01

Abstract

The elusive structure of compressed, melt-quenched As 2 Se 3 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 ̊ 2 ) upon increasing pressures up to 30 GPa. ̊ and bond variance σ 2 (from ∼0.004 to 0.008 A ∼2.42 to 2.44 A) 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-As 2 Se 3 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.
2016
File in questo prodotto:
File Dimensione Formato  
PRB_93_214205_2016.pdf

solo gestori di archivio

Descrizione: Pdf articolo
Tipologia: Versione Editoriale
Licenza: NON PUBBLICO - Accesso privato/ristretto
Dimensione 888.22 kB
Formato Adobe PDF
888.22 kB Adobe PDF   Visualizza/Apri   Richiedi una copia

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11581/396312
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 14
  • ???jsp.display-item.citation.isi??? 13
social impact