Polarized Raman spectra of hematite and assignment of external modes

Abstract Notwithstanding the significant practical importance of hematite, α‐Fe2O3, the complete assignment and understanding of the Raman spectrum acquired on this crystalline solid are uncertain. Above all, only one of the two external Eg phonons arising from the Γ point has been resolved and hence assigned. It is well known that the Eg mode at 294 cm−1 has been attributed to one of the two external phonons arising from the Γ point. To this end, we have undertaken studies to examine the polarized Raman scattering on a pure single crystal to gain a better understanding and assignment of phonons arising from the Γ point in the Raman spectrum of hematite. Here, we resolve and assign the previously unidentified external Eg phonon at 245 cm−1 and, additionally, confirm that the band at 294 cm−1 is an external Eg phonon, in the first‐order Raman spectrum of hematite. Further, our polarized Raman spectra display interesting polarization behavior of the 2LO mode at 1320 cm−1, where this band is only Raman active in ei||es polarization configurations.