Features of Oxidation of Bismuth by High-Density Water-Oxygen Fluid

The paper presents the results of a study of oxidation of bulk bismuth samples by oxygen, water vapor, and water-oxygen fluid in a reactor heated to 873 K at a rate of 1 K/min with high-density reagents ( $$\rho_{{\rm O_{2}}}\le0.62$$ and $$\rho_{{\rm H_{2}O}}\le5.24$$ mol/dm3). The results include temperature dependences of the pressure of the reaction mixtures. The rate of oxygen consumption is found from these dependences through the Redlich–Kwong equation of state. Formation of dense oxide film during the oxidation of bismuth in the O2 environment was shown. No oxide formation was detected during treatment of bismuth with water vapor. The combined action of O2 and H2O molecules enhances the oxidation of bismuth and leads to formation of oxides of different compositions and morphologies. At $$T>720$$ K, the bismuth oxidation rate was observed to increase due to the higher pressure of saturated bismuth vapor.