The influence of Zn-dopant on the precipitation of α-FeOOH in highly alkaline media

The influence of a Cr-dopant on the properties of α-FeOOH particles precipitated in highly alkaline media

“…The lattice band corresponding to the vibration parallel to the c-axis in ␣-FeOOH (ν Lc ), positioned at 405 cm −1 in the spectrum of reference sample G, also showed a gradual shift towards 401 or 402 cm −1 in the spectra of samples obtained at r values between 2.91 and 6.98. Furthermore, the lattice band positioned at 374 cm −1 in the spectrum of reference sample G showed a shift towards lower wave numbers with an increase in the initial concentration of Cr ions, which is unlike the behaviour of this band in the spectra of ␣-FeOOH samples synthesised in the presence of some other cations [21][22][23][24][25]. These observations could be explained by a specific influence of Cr ions compared with other cations on the shape of ␣-FeOOH particles, as observed by FE-SEM (Fig.…”

“…Such tendency was not noticed in studies of the influence of some other cations on the formation of ␣-FeOOH [21][22][23][24][25]. In these studies the position of that lattice band remained the same or has been shifted slightly to lower wave numbers with an increase in the initial concentration of metal ions.…”

“…In the presence of higher concentrations of Cr ions low-crystalline Cr-ferrihydrite or mixed Fe-Cr hydroxide was formed. • The presence of Cr ions in the precipitation system influenced an increase in length (c-axis direction) of ␣-FeOOH particles (from 150-200 nm in reference sample to 200-300 nm), but not as much as was observed in the case of some other cations [21][22][23][24][25]. At the same time, width (b-axis direction) was increased from 40-60 nm to 80-120 nm.…”

Fabrication and magnetic properties of NiFe2O4 nanorods

“…According to Ref. [21], the diameter of the -FeOOH nanorod reduced in the above process, resulting in the increase in aspect ratio. The morphology of the precursor obtained by enwrapping the complex of citric acid and Ni 2+ on the surface of -FeOOH nanorods was the same as that of -FeOOH.…”

“…[21]) were dissolved in deionized water. According to m(NaOH)/m(FeCl 2 ) of 1.0:3.5 (mass ratio), NaOH was dissolved in another deionized water to prepare alkali liquor.…”