The Influence of Dysprosium Addition on the Crystallization Behavior of a Chalcogenide Selenide Glass Close to the Fiber Drawing Temperature

• Published in: Journal of the American Ceramic Society Vol. 95; no. 12; pp. 3834 - 3841
• Main Authors: Cheng, Yin, Tang, Zhuoqi, Neate, Nigel C., Furniss, David, Benson, Trevor M., Seddon, Angela B.
• Format: Journal Article
• Language: English
• Published: Columbus Blackwell Publishing Ltd 01.12.2012; Wiley Subscription Services, Inc
• Subjects: Chalcogenides; Crystallization; Dysprosium; Glass; Heating; Materials science; Melting; Melts; Quenching; Reheating; Scanning electron microscopy; Silica; Temperature effects
• ISSN: 0002-7820; 1551-2916
• DOI: 10.1111/jace.12014

A series of chalcogenide glasses based on Ge16.5Ga3As16Se64.5 (at.%), doped nominally with 0, 1000, 3000, and 6000 ppmw (by weight) of Dy foil, is prepared by using conventional method: melting inside a sealed silica glass ampoule, which is rocked to homogenize the melt, followed by melt quenching and annealing. Examination of the as‐prepared glasses, using scanning electron microscopy with energy dispersive X‐ray spectroscopy (SEM‐EDX), reveals that dysprosium‐rich areas of devitrification have a tendency to form at the surfaces of the prepared chalcogenide glasses which have been adjacent the silica ampoule walls during the final stages of melting, quenching, and annealing; such dysprosium‐rich areas of devitrification are not observed using SEM‐EDX at the noncontacting‐silica‐ampoule chalcogenide glass surface nor in the interior of the chalcogenide glass bulk. Samples taken from the interior of the prepared glass boules exhibit an increase in glass transition of up to 9 ± 2°C, and rise in other isoviscous temperatures, with increasing dysprosium content. Extended isothermal heat treatment at the estimated fiber‐drawing temperature, followed by quenching to room temperature and analysis using SEM‐EDX and X‐ray diffraction (XRD), is carried out to investigate the influence of dysprosium addition on crystallization behavior on reheating the chalcogenide glass. Increasing the dysprosium level, surprisingly, appears on the one hand to help to restrain crystallization of the bulk glass on glass reheating, whereas on the other hand, and at the same time, to exacerbate the surface devitrification on glass reheating. The bulk crystallizing phase on reheating the glasses is distorted face‐centered cubic α‐Ga2Se3. The same phase was found to grow in the bulk glass during melt cooling of Dy‐doped Ge–As–Ga–Se glasses in our earlier work.