Abstract
The reaction between SrO(s) and W(s) at high temperatures has been studied by a technique of mass-spectrometric thermal analysis. It is found that the vaporization caused by the reaction proceeds in three stages. In the first stage, the gaseous product Sr(g) appears above 1,285 K, leaving the solid product SrWO4(s). In the second stage, the vaporization of Sr(g) occurs again above 1,580 K from the residual SrO(s) unreacted with W(s) during the course of the first stage. In the third stage, SrWO3(g), SrWO4(g), and small Sr(g) vaporize from SrWO4(s). The areas under the curves of the mass-spectrometric thermal analysis have been calculated by a modified integration method. From these areas the apparent partial pressure of Sr(g) in the first stage and also the molar ratio of the gaseous and solid reaction products Sr(g) and SrWO4(s) have been determined. Furthermore, the apparent pressures of SrWO3(g) and SrWO4(g) in the third stage have been obtained by a sensitivity calibration method.
