STRUCTURE OF 50NA(2)O.XAL(2)O(3).(50-X)P2O5 AND (50-X 2)NA2O.XAL(2)O(3).(50-X/2)P2O5 GLASSES/

The structure of 50Na(2)O.xAl(2)O(3).(50-x)P2O5 and (50-x/2) Na2O.xAL( 2)O(3).(50-x/2) P2O5 glasses have been analysed by means of a combinat ion of x-ray diffraction measurements and molecular dynamics (MD) simu lations. Pairwise potentials of P-O and Al-O pairs used were extracted from an ab initio Hartree-Fock self consistent calculation using the GAUSS80H computer program. In our MD simulation the oxygen coordinatio n number around the Al atoms decreased with an increasing Al2O3 conten t. This is consistent with the results of previous reports using AlK a lpha x-ray fluorescence spectroscopy and Al-27 magic angle spinning nu clear magnetic resonance spectroscopy. We have proposed a modification of the method of the combining the radial distribution analysis and M D simulation. The distributions of the first Na-O and O-O peaks are in vestigated using this method. It indicates that the shapes of these pe aks val ies with the glass composition.