 1  Author
 M. Bionducci, F. Buffa, G. Licheri, G. Navarra, B. BouchetFabre, J. M. Tonnerre  Requires cookie*   Title
 Determination of the Partial Structure Factors of Amorphous CuZr by Anomalous XRay Scattering and Reverse Monte Carlo    Abstract
 Anomalous Xray Scattering experiments have been performed to study the local order in an amorphous CuZr sample prepared by mechanical alloying. The three partial structure factors were extracted both using a regularization algorithm to solve an illconditioned system of linear equations and applying the reverse Monte Carlo technique to the experimental data. Then the short range atomic distributions of similar samples prepared by different methods and investigated by different techniques are compared.   
Reference
 Z. Naturforsch. 51a, 71—82 (1996); received November 15 1995   
Published
 1996   
Keywords
 Amorphous Alloys, Anomalous Xray Scattering, Regularization Algorithm, Reverse Monte Carlo, Partial Structure Factors   
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 default:Reihe_A/51/ZNA199651a0071.pdf    Identifier
 ZNA199651a0071    Volume
 51  
2  Author
 Uwe Hoppe, Günter Walter, Rainer Kranold, Dörte Stachel  Requires cookie*   Title
 An Xray Diffraction Study of the Structure of Vitreous P2O5    Abstract
 Recently, the lengths of the two P0 bonds in the P0 4 tetrahedron were obtained by neutron diffraction of high realspace resolution. By use of the present Xray diffraction experiments, the PP distance belonging to pairs of cornerlinked P0 4 units is determined. Using this length of (294 ± 2) pm and taking into account the P0 bond distance to the bridging oxygen atom of 158 pm, a mean POP angle of 137° ± 3° is calculated. The reverse Monte Carlo simulations fit the neutron and Xray structure factors. The POP angle distribution obtained this way possesses a mean angle of 141°. An interpretation of the first scattering peaks is presented by analysing the occupancy and the distances of various coordination shells by use of model configurations. The low occupancy of the first shells allows the application of the schematic hole model of Dixmier. The first Xray diffraction peak at 13 nra" 1 is related to the PP2nd shell, the shoulder at 20 nm 1 arises from the P0 2nd shell. The most similar crystalline structure with vitreous P2O5 is the orthorhombic P2O5, form II. But it has more effectively orientated terminal oxygen atoms and, thus, a higher packing than the glass.   
Reference
 Z. Naturforsch. 53a, 93—104 (1998); received December 22 1997   
Published
 1998   
Keywords
 Vitreous P 2 0 5, Xray Diffraction, Shortrange Order, Reverse Monte Carlo   
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