Structural and optical properties of chromium-doped hematite (α-Fe2O3) nanoparticles

Cr-doped hematite nanoferrites series were synthesized by calcination of Cr-doped magnetites at 1100 °C for 4 h. This study revealed that the samples have decomposed into hexagonal hematite materials (α-Fe2O3 and α-Cr2O3) by calcining effect. The crystallite size R, density Dx, the energy band gab Eg showed decrease with increase of Cr3+ ion concentration x, whereas the lattice constants (a and c), unit cell volume, specific surface area S, the strain Ԑ, Debye temperature ӨD and jump rate showed increase. Two absorption characteristic bands ν1 and ν2 of hematite nanoferrites were observed in IR spectra. Two absorption bands are recorded in the UV–vis absorption spectra of calcined CrxFe(3-x)O4 nanoparticles 287 nm and 372 nm. The observed XPS spectra of the samples have revealed structural transformation of the magnetite to hexagonal hematite (α-Fe2O3 and α-Cr2O3) suggesting a hopping process between Fe3+ and Cr3+ ions among the B-sites.