Bond Distances and Coordination Analysis

The interatomic bond distances are investigated in terms of pair distribution function (PDF). The maximum of the first peak in the PDF curves derived by MD corresponds to the average bond distance and this value was obtained for all the cation-oxygen (M-0) and cation-cation (M-M) species in the analysed systems. The values are reported in Table8.5 and are clearly in agreement with the theoretical and 

Xhe V +-0 PDF curve, reported in Fig. 8.3, shows the presence of a shoulder at about 1.65 A that can be associated to the presence of the typical vanadyl (V=0) bonds that are found in vanado-phosphate systems. 

The contribution of different coordination environments for the and ions, as a function of the ratio V +/Vtot, is reported in Table 8.7 for 33LiVP systems. The MD results highlight differences in coordination, due to the various percentages of ions in the glass matrix. If the amount of ions is lower, ions tend to be mainly four-folded coordinated with respect to the 33LiVP-48, where the V  

The predominant structural unit is the octahedral one, consistent with the results obtained for NaVP systems. 

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