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 t o avoid the empirical trial-and-error mode of synthesis. The approach used makes possible to predict the optimum conditions through stability and yiel d diagrams, relating the equilibrium concentration of all the present speci es as a function of temperature, pressure, solution pH and input reagent co ncentrations. The theoretical predictions were verified by experiments at t hese optimum conditions. The results showed that the thermodynamic model is adequate to predict the synthesis conditions for which the strontium tungs tates are stable and can be obtained in a phase-pure form.