Raman Spectroscopy of Natural Titanomagnetites

Abstract

The Raman spectral patterns of analyzed natural titanomagnetite samples revealed peaks at 670-680 cm -1 , 544-603 cm -1 , 407-495 cm -1 and 373-392 cm -1 that correspond to the A 1g , T 2g (2), T 2g (3) and E g vibrational modes of the spinel Fd3m space group. Previous studies of titanomagnetite Raman spectra patterns have suggested the behavior of these peaks refl ect the distribution of Fe 2+ -O, Fe 3+ -O and Ti 4+ -O bonds within the titanomagnetite crystal structure. The peak intensities of each vibrational modes are observed to be relative, reflecting the re-distribution of Fe 2+ and Fe 3+ in both the tetrahedral and octahedral sites as a function of Ti concentration. Existing titanomagnetite Raman spectroscopy studies are limited to analysis of synthetic titanomagnetite. In this study, Raman spectral patterns from natural titanomagnetite i.e., magnetite-ulvöspinel solid solution samples were analyzed to determine behavior of Raman spectrum peak positions and intensities due to changing content of Ti 4+ , Fe 2+ and Fe 3+ .