Chemical disorder and network structure of glassy As2Te3

Telluride glassy systems are widely used for phase-change optical recording. They are also promising materials for far-IR applications. The atomic structure of telluride glasses is much less known compared to their sulphide and selenide counterparts. A typical example is glassy As2Te3, which exhibits a significant chemical disorder, characterized by homopolar As-As and Te-Te bonds. Recently, high-pressure experiments using glassy As2Te3 have shown a number of unusual phenomena. Surprisingly, our high-energy X-ray diffraction measurements have shown a distinct decrease of homopolar bonds in g-As2Te3, recovered from 8.5 GPa, while an increase of chemical disorder at high pressure was expected. Neutron diffraction measurements are complementary to X-ray scattering results for this particular system and will allow a detailed structural model for g-As2Te3 to be constructed.