Pulsed neutron diffraction study of the short range structure in amorphousarsenic chalcogenides

The pair distribution functions G(r)'s of As2S3 and As2Se3 glasses were obt ained from the structure factors S(Q)'s. The structural parameters were ref ined by applying the correlation method in the (Q,Q.i(Q)) space. Although t he structural parameters by PND were somewhat different from those by XRD, the peak shape in PND was clearer than in XRD. The local structure of the g lasses was similar to that of orpiment (As2S3 crystal) with AsS3 pyramids, However, the nearest neighbor distances of As-S pair were 2.29 Angstrom in PND, 2.27 Angstrom in XRD, and 2.25 Angstrom (average value of As-S bonds i n crystal), implying the little expansion of AsS3-type pyramids and the var iation in linkage of pyramids. (C) 1999 Elsevier Science Ltd. All rights re served.