Extended-range order in glasses
- Argonne National Lab., IL (United States)
- Univ. of Pennsylvania, Philadelphia, PA (United States)
- Rutherford-Appleton Lab., Chilton (United Kingdom)
The origin of intermediate-range order (IRO) in glasses remains one of the outstanding problems in condensed matter physics since indirect early evidence for its manifestation was seen in the Raman spectra of some glasses. The most general and persistent evidence of IRO, however, is the first sharp diffraction peak (FSDP), the feature observed at low wave-vector in the average structure factor S(Q) of many systems, including oxide, silicate and chalcogenide glasses and complex liquids. The FSDP is characterized by the fact that product of its wave vector Q{sub 1} and the nearest-neighbor distance r{sub 1} lies in the range 2.2--2.8, implying correlation lengths of the order of 2.5 r{sub 1}. The origin of the FSDP is controversial: it has been variously attributed to the presence of layer-like structures in the glass, to random packing of appropriate structural motifs, and to chemical ordering of voids and cations. Regardless of its origins, the FSDP clearly represents correlation lengths greater than those associated with the nominal building blocks of oxide and chalcogenide glasses. In this Letter, the authors report unambiguous evidence of structure extending well beyond the correlation length typical of the FSDP, based on recent neutron and anomalous x-ray scattering experiments on rubidium germanae glasses. They show that this structure is related to chemical ordering of the metal atoms and associated topological ordering of the oxygens.
- Research Organization:
- Argonne National Lab., IL (United States). Materials Science Div.
- Sponsoring Organization:
- USDOE, Washington, DC (United States); National Science Foundation, Washington, DC (United States)
- DOE Contract Number:
- W-31109-ENG-38
- OSTI ID:
- 10188255
- Report Number(s):
- ANL/MSD/PP-77977; ON: DE95001063; CNN: Grant DMR-90-01704; TRN: AHC29425%%83
- Resource Relation:
- Other Information: PBD: Nov 1992
- Country of Publication:
- United States
- Language:
- English
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