Phase diagram of the pseudobinary system Bi–Co–O

Samples with different ratios of Bi2O3 and Co2O3 were prepared by ceramic route. Based on the results of differential thermal analysis, X-ray powder diffraction, SEM–EDXA and FactSage database the phase diagram of the Bi–Co–O diagram in air atmosphere was assessed and calculated using the FactSage software. The sillenite structure of Bi24Co2O39 was identified and the single phase homogeneity range of Bi24Bi2−xCoxO39, x = 0.9–2.0 was determined by Rietveld analysis and SEM–EDXA. To verify the composition in the various parts of the phase diagram at elevated temperatures, a number of high-temperature annealing experiments was performed followed by rapid quenching to room temperature.