Thermodynamic model and structure of ZnO-MoO3-P2O5 glasses

In the present work the Shakhmatkin & Vedishcheva thermodynamic model was constructed for the ZnO-MoO3-P2O5 glasses. On the basis of equilibrium phase diagrams and the crystal structural data the glass was considered as an ideal solution of three oxides and nine compounds representing different Q(n) units. For the components considered in the model no thermodynamic data were available in contemporary thermodynamic databases. Therefore new method of parameterization of the thermodynamic model was proposed based on the known structural data. Four compositional series were considered. The first series (A) has equimolar content of ZnO/P2O5-(0.5-x/2)[ZnO.P2O5].xMoO(3). The other three series have a constant content of one of the components, (B) 0.1ZnO.yMoO(3).(0.9-y)P2O5, (C) zZnO.0.2MoO(3). (0.8-z)P2O5 and (D) (0.5-t)ZnO.tMoO(3).0.5P(2)O(5). For these compositional series the Q(n) distribution was obtained from the P-31 MAS NMR spectra by Subcik et al.((1)) Using these experimental data the temperature independent reaction Gibbs energies of formation of compounds considered in the thermodynamic model were estimated by minimization of the sum of squared deviations between experimental and calculated relative abundances of Q(n) units.