Structural properties of As2Se3 fibers

Nuclear quadrupole resonance (NQR) studies of rapidly-drawn fibers of glassy As2Se3 reveal that significant structural changes occur as a function of draw rate. Pulsed As-75 NQR echo measurements have been performed on freshly prepared and aged samples of glassy As2Se3 fibers at three different draw rates (5, 41 and 75 m/min). The As-75 NQR lineshapes exhibit systematic trends in both the linewidths and line asymmetries. Fibers drawn at the most rapid rate exhibit a second resolved peak in the NQR lineshape that is attributed to the presence of As-As bonds even though the glass is nominally stoichiometric. Presumably the As-As 'wrong bonds' are compensated by the presence of Se-Se bonds. Annealing the fibers for several hours near 200 degrees C produces changes in the NQR lineshapes but does not result in NQR lineshapes that are indicative of the bulk glass. These results are consistent with measurements of structural relaxation as obtained from differential scanning calorimetry in glassy As2Se3 fibers.