Raman Spectroscopy and Scanning Electron Microscopy of the Bismuth Sillenites Bi$_{25}$InO$_{39}$ and Bi$_{25}$FeO$_{39}$

The Raman spectrum of Bi$_{25}$InO$_{39}$, a new type of bismuth sillenite, is reported along with the spectra of Bi$_{25}$FeO$_{39}$. Their spectra are remarkably similar to each other and to other bismuth sillenites reported in the literature. The similarities show that the new samples were successfully grown in the sillenite structure. The parameters of each Raman mode were obtained by fitting the spectra to a Lorentzian oscillator model, and the modes were assigned to symmetry-allowed modes of the I23 space group. The assignments were made by comparison to other materials with the sillenite structure. Scanning Electron Microscope images of the samples are also presented.