  The present study investigates the effect of different reaction times on the
crystallinity, surface morphology and size of iron oxide nanoparticles. In this
synthetic system, aqueous iron (III) nitrate (Fe(NO$_3$)$_3\cdot9$H$_2$O)
nonahydrate, provided the iron source and triethylamine was the precipitant and
alkaline agent. The as-synthesised iron oxide nanoparticles were characterised
by X-ray diffraction (XRD), Rietveld analysis, Scanning Electron Microscopy
(SEM) and Fourier transform infrared spectroscopy (FTIR). Prolonged reaction
times indicated the change on nanoparticle shape from elongated nanorods to
finally distorted nanocubes. Analysis on the crystallinity of the iron oxide
nanoparticles suggest that the samples mainly consist of two phases, which are
Goethite ($\alpha$-FeOOH) and Hematite $(\alpha$-Fe$_2$O$_3$), respectively.
