Abstract
Bulk AsxGe40-xSe60 (with x = 0, 10 and 20 at.%) glasses were prepared using the melt-quench technique. Short range order (SRO) was examined by X-ray diffraction using Cu(K alpha) radiation in the wave vector interval 0.28 <= K <= 6.5 angstrom(-1) For Ge40Se60 glass, the first sharp diffraction peak (FSDP) is located at K = 1.0 angstrom(-1) and shifted to higher K-values with increasing As content. Consequently, the coherence length has a maximum value for the binary glass. The SRO parameters have been obtained from the total distribution function, T(r). The inter-atomic distances obtained from the first and second peak are, r(1) = 2.37 +/- 0.01 angstrom and r(2) = 3.93 +/- 0.01 angstrom, in good agreement with previous works. The fundamental structural unit of the studied glasses is the Ge-Se-4/2 tetrahedral. (c) 2005 Elsevier B.V. All rights reserved.