Motivation:

1. Nanoscale Order vs. Glass Forming Ability of Chalcogenide GlassesStephen G. Bishop, University of Illinois at Urbana-Champaign, DMR 1005929 (a) • Motivation: • Previous Fluctuation Transmission Electron Microscopy (FTEM) measurements demonstrated the presence of nanoscale ordering in metastable (poor glass-forming) alloys of phase change materials (PCM). • Does nanoscale ordering persist, increase, or decrease in good glass-forming chalcogenide alloys? • Results: • The nanoscale order of GexSe1-x alloys – as measured by the variance spectra – diminishes with increasing selenium content. • Extreme reduction of nanoscale ordering observed in good glass-forming GexSe1-x alloys (0<x<0.4). (b) (a) Variance vanishes with increasing selenium content in GexSe1-x binary alloys. (b) The reduction in nanoscale order, as measured by the variance magnitude, closely follows the glass-forming ability.

2. Nanoscale Order vs. Glass Forming Ability of Chalcogenide GlassesStephen G. Bishop, University of Illinois at Urbana-Champaign, DMR 1005929 Broader Impact • Significance in our field: Strong evidence for the sensitivity of FTEM in detecting nanoscale order in amorphous samples • Significance outside our field: • First ever FTEM measurements performed on good glass-forming chalcogenide alloys. • Completely new nanoscale structural information for researchers in the glass physics community. • Future: FTEM measurements can provide new data that may help uncover the origin of the first sharp diffraction peak (FSDP,) a diffraction feature which is still hotly debated within the glass physics community.