engleski

Impact of cadmium and phosphate ions on the hematite nanorings formation

It has been suggested that the addition of divalent metal cations during the hydrothermal synthesis of hematite (a-Fe2O3) in the presence of phosphate ions has a strong impact on the hematite morphology, crystal growth and dissolution (Gotic et al., J. Mol. Struct. 993 (2011) 167). In this work, the same system was modified with divalent cadmium ions and the impacts of cadmium and phosphate ions on the hematite nanorings formation have been studied. It has been found that formed hematite and akaganeite (b-FeOOH) precipitates did not contain any trace of cadmium impurities. On the contrary, the modification with divalent cadmium cations changes the PO4 3
/Fe3þ molar ratio in the system. Upon the addition of cadmium ions the PO4 3
/Fe3þ molar ratio changes from 0.036 in a pure system to 0.051 in the cadmium modified system. The relative increase of phosphate concentration at early stage of precipitation induced the change of spindle to spherical morphology and formation of the poorly crystallised akaganeite-like phase. The appearance of akaganeite-like phase directly correlated with he delay in the crystallisation of hematite. Besides, the relative increase of phosphate concentration has the prevailing effect for the change of spindle to pseudosphere and nanotube to nanoring particle morphologies.

Hematite ; Akaganeite ; Phosphate ; Mossbauer ; Nanorings ; TEM

http://dx.doi.org/10.1016/j.molstruc.2016.12.089