MICROSTRUCTURAL EVOLUTION IN MELT-QUENCHED AMORPHOUS SE DURING MECHANICAL ATTRITION

Microstructural evolution of an as-quenched amorphous Se sample during ball milling was investigated by use of x-ray diffraction, a differen tial scanning calorimeter, infrared and Raman spectroscopy, as well as x-ray photoemission spectroscopy. It was found that the as-quenched a morphous Se is crystallized completely into a nanocrystalline trigonal Se phase after milling for 30 min. Further milling of the as-milled n anocrystalline trigonal Se resulted in a transformation into another a morphous Se phase, which exhibits a lower crystallization temperature and a smaller crystallization enthalpy compared to those for the as-qu enched amorphous Se according to thermal analysis. Infrared and Raman spectroscopy measurements revealed that the as-milled amorphous Se is mainly composed of Se-n polymeric chains that are fundamentally differ ent from the as-quenched amorphous Se in which the Se-8 ring structure is predominant. However, despite the phase evolution and changes in m olecular structure in Se, x-ray photoemission measurements indicated t hat no detectable changes in electronic properties (e.g. the density o f valence states, the binding energies of core levels, and the charact eristic energy loss functions) were observed among different states of Se samples. [S0163-1829(98)00417-2].