engleski

The influence of Cd-dopant on the properties of alpha-FeOOH and alpha-Fe2O3 particles precipitated in highly alkaline media

The effects of Cd-dopant on the phenomenology of the precipitation of alpha-(Fe, Cd)OOH and alpha-(Fe, Cd)2O3 particles, the formation of solid solutions, particle size and their geometrical shapes were investigated using Mössbauer and Fourier transform infrared (FT-IR) spectroscopies, field emission scanning electron microscopy (FE SEM) and energy dispersive X-ray analysis (EDS). The formation of merely alpha-(Fe, Cd)OOH solid solutions was measured up to r = 0.0196, where r = [Cd]/([Cd] + [Fe]). The formation of two types of solid solutions, alpha-(Fe, Cd)OOH and alpha-(Fe, Cd)2O3 was found at r between 0.0291 and 0.0698, whereas the formation of an alpha-(Fe, Cd)2O3 solid solution alone was obtained at r = 0.0909. The incorporation of Cd-substitutions into alpha-FeOOH and alpha-Fe2O3 structures decreased the Bhf values of the corresponding hyperfine magnetic field. The IR band at 639 cm− 1, recorded for alpha-FeOOH, was found to be sensitive to Cd-substitutions. With an increased r value a gradual elongation of alpha-(Fe, Cd)OOH particles along the c-axis was observed, with the maximum elongation (600– 700 nm) obtained at r = 0.0476. At the same time, particle width (b-axis direction) and thickness (a-axis direction) showed a gradual decrease. With a further increase in the r value the length of alpha-(Fe, Cd)OOH particles rapidly decreased. alpha-(Fe, Cd)2O3 particles 100– 200 nm in size were obtained at r = 0.0909.

Cadmium ; Tetramethylammonium hydroxide ; alpha-FeOOH ; alpha-Fe2O3 ; 57Fe Mössbauer ; FT-IR ; FE SEM ; EDS

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