Raman scattering and phonon anharmonicity as a tool for assisting TiO2-based ceramics synthesis

In this paper is shown that Raman spectroscopy can be used as an alternative technique to look for the best synthesis conditions of TiO2-based ceramics. The advantage of the Raman spectroscopy in comparison to X-ray diffraction, for example, is the reduced time to acquire the Raman spectrum, normally few seconds, using very small samples. In the TiO2 case, this additional advantage is due to the phonon anharmonicity, in which the frequency temperature coefficient ∂ω/∂T is positive, contrary to the majority of materials. By taking the Raman spectrum in different sample temperatures and monitoring spectral modifications in the low wavenumbers range, it is possible identify the presence of non-reacted TiO2, which indicates that the ideal synthesis conditions were achieved or not. The presented methodology was successfully applied to the synthesis of NixPb1−xTiO3 ceramics.