Synthesis and properties of Ti-substituted goethites and hematites

The objective was to synthesize Ti-substituted goethites and hematites and to characterize them using x-ray diffraction, thermogravimetric analysis, coulimetry, optical and Mossbauer spectroscopies, and magnetic data in order to determine the evidence of Ti substitution for Martian spectral data. Evidence is provided that up to 4 mole percent can be incorporated into the goethite structure during the low temperature synthesis. Because the spectral data in the visible and near-IR are not sensitive to the degree of Ti-substitution in goethites and hematites, such data cannot be used to infer the presence or absence of Ti substitution in Martian hematites and goethites.