Investigation of the Equilibrium Germanium-Substituted Wustite with Metal and Spinel Solutions in the Fе-Gе-O System

Abstract

The phase equilibrium in the Fe-Ge-O system is investigated by measuring EMF of galvanic elements with solid oxygen-conductive electrolytes. The samples for investigation were prepared by the solid phase reaction at 900 °C. The samples were analyzed to determine the total and phase composition. The gross composition of the samples was refined by chemical analysis. The iron content was determined by the standard method of bichromatometric titration, while that of germanium was determined by the photometric method, which is based on measuring the optical density of the colored colloid solution of germanium phenyl fluoronate, which is formed upon the interaction of germanium dioxide with phenylfluorone in the acidic medium. The phase composition was established using X-ray diffractometry and electron probe microanalysis using a DRON-3 diffractometer and a JEOL JSM-6460LV computer controlled scanning (raster) microscope. The experimental function of EMF galvanic elements of temperature is formulated. After processing the obtained data, the equilibrium oxygen pressures over the samples were calculated, the solubility of germanium in iron monoxide (wustite) was determined, the phase composition of the regions bordering the wustite region was established, the isothermal sections of the state diagram of the system were constructed at 1173 and 1273 K in the equilibrium region of the wustite solution with metallic and spinel phases