Local structures in glassy and liquid As2Se3 – an anomalous X-ray scattering study

Anomalous X-ray scattering experiments have been performed for glassy (g-) As2Se3 at room temperature and for liquid (l–) As2Se3 at 400 °C in order to clarify the role of each constituent for the short- and intermediate-range order (SRO and IRO). The differential structure factors ΔiS(Q)s close to the As and Se K edges have been obtained from a detailed analysis. The first nearest neighbour distances around both As and Se are about 0.24±0.02 nm for both g- and l-As2Se3, which would support the SRO model that g- and l-As2Se3 have an SRO similar to the corresponding crystal. The prepeak in S(Q) for g-As2Se3 seems to be dominated by a partial structure factor SAsAs(Q), which reveals the existence of the As–As IRO with a correlation length of about 0.52 nm. In l-As2Se3, however, the substitution of Se atoms into some As sites would cause a contribution in ΔseS(Q) at the prepeak position.