The structure of densified As 2O 3 glasses

Abstract

In situ high energy X-ray diffraction and Raman experiments have been carried out to probe the structure changes of vitreous As 2O 3 under pressure. The first sharp diffraction peak reduces in intensity up to 10 GPa, indicating a breakdown of intermediate range order with pressure. All features in the Raman spectra broaden with increasing pressure up to 11.6 GPa. The mode at 378 cm −1 associated with As 4O 6 molecule-like vibrations increases in intensity up to 6.2 GPa and decreases at higher pressures. In addition, X-ray and neutron structure factors have been measured for normal density and permanently densified As 2O 3 glasses recovered from 10 and 23 GPa. The results show the local AsO 3 pyramids and 3-membered rings essentially remain intact after compression. The increase in density is mainly associated with an inward shift of the third nearest neighbor peak in the X-ray radial distribution function, which indicates an increased packing of 3-membered AsO 3 rings.