Theoretical predictions and experimental results of the hydrothermal processing of strontium tungstates

The hydrothermal processing conditions of strontium tungstate powders were studied by using a thermodynamic model of electrolytic solutions in order to avoid the empirical trial-and-error mode of synthesis. The approach used makes possible to predict the optimum conditions through stability and yield diagrams, relating the equilibrium concentration of all the present species as a function of temperature, pressure, solution pH and input reagent concentrations. The theoretical predictions were verified by experiments at these optimum conditions. The results showed that the thermodynamic model is adequate to predict the synthesis conditions for which the strontium tungstates are stable and can be obtained in a phase-pure form.