Short-range order of compressed amorphous GeSe2
L Properzi1, A Di Cicco2, L Nataf3
11] Physics Division, CNISM, School of Science and Technology, Università di Camerino, I-62032 Camerino (MC), Italy [2] Synchrotron Soleil, L'Orme des Merisiers, St. Aubin 91192 Gif s/Yvette, France.
Scientific Reports
|May 15, 2015
Summary
Amorphous germanium diselenide (a-GeSe2) remains amorphous under high pressure, undergoing metallization around 10-15 GPa. Structural analysis reveals a transition from tetrahedral to octahedral coordination, indicating a reversible non-isostructural phase change.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Solid State Chemistry
Background:
- Understanding the pressure-induced structural evolution of amorphous materials is crucial for their technological applications.
- Amorphous germanium diselenide (a-GeSe2) exhibits unique properties influenced by its local atomic arrangement.
Purpose of the Study:
- To investigate the structural behavior of a-GeSe2 under high pressure up to 30 GPa.
- To identify pressure-induced phase transitions and metallization in a-GeSe2.
Main Methods:
- Combined use of two-edges X-ray absorption spectroscopy (XAS) and angle-dispersive X-ray diffraction.
- Analysis of XAS data at ambient conditions to reconstruct the first-neighbor distribution function.
- Structure refinement using XAS to identify compression stages.
Main Results:
- a-GeSe2 remains amorphous up to 30 GPa.
- A reversible 1.5 eV red-shift in Ge K-edge energy, indicating metallization, occurs between 10-15 GPa.
- Two distinct compression stages were identified, involving changes in bond distances, disorder, and coordination number.
Conclusions:
- High pressure induces a reversible non-isostructural transition in a-GeSe2, characterized by a gradual conversion from tetrahedral to octahedral coordination.
- The observed metallization and structural changes provide insights into the pressure-dependent properties of chalcogenide glasses.
