Temperature‐Dependent Raman Study of Nanostructured and Multifunctional Materials

Abstract

The scope of this paper is temperature dependence of Raman spectra in several nanocrystalline materials and iron‐based single‐crystals. The Raman results presented and analyzed here are related to TiO2 nanopowders (with dominant anatase and brookite phase) and ZnxCd1−xSe single layers measured at different temperatures. Temperature‐dependent Raman spectra of iron‐based sulphides and selenides (BaFe2S3 and BaFe2Se3), as well as alkali‐doped iron selenides (KxFe2−ySe2 and K0.8Fe1.8Co0.2Se2) are also analyzed. A physical model, including thermal expansion as well as three‐ and four‐phonon anharmonic effects, is used to quantitatively analyze temperature evolution of the characteristic Raman mode self‐energies for the materials of interest. It is demonstrated how this model can be used as a tool for predicting the temperature of structural and phase transitions, with critical scrutany of its limitations.