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'Short range order' in keywords Facet   Publication Year 1997  [X]
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1Author    Uwe Hoppe, Günter Walter, Dörte Stachel, Andrea Barz, AlexC. HannonRequires cookie*
 Title    Neutron and X-ray Diffraction Study on the Structure of Ultraphosphate Glasses  
 Abstract    The high real-space resolution of neutron diffraction experiments which is provided by use of the epithermal neutrons from spallation sources was exploited in order to differentiate the unlike P-O bonds existing in the P0 4 units of phosphate glass networks. The 2 P-O distance peaks, separated by about 12 pm, which were found in the zinc and the calcium ultraphosphate glasses studied are assigned to oxygen sites on bridging (O b) and terminal (O X) positions. The mean P-O distances are nearly invariable versus the growing metal oxide content which results from an elongation of the P-O b and P-O t bonds. The bond lengths which are known from the related crystal structures and from ab initio calculations show almost the same behaviour. The discussion of further details of the crystal structures leads to the conclusion that P-O b rather than P-O t distances should show more details in case of diffraction measurements of even higher real-space resolution. The change of the Zn-O coordination number from 6 to 4 versus increasing ZnO content, which was obtained in previous X-ray diffraction experiments, is confirmed by the recent combination of neutron and X-ray diffraction data. On the other hand, the Ca-O coordination number of about 6 is almost invariable. 
  Reference    Z. Naturforsch. 52a, 259—269 (1997); received July 6 1996 
  Published    1997 
  Keywords    Neutron diffraction, X-ray diffraction, Phosphate glasses, Short-range order 
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 TEI-XML for    default:Reihe_A/52/ZNA-1997-52a-0259.pdf 
 Identifier    ZNA-1997-52a-0259 
 Volume    52