Abstract
We study nanograin size confinement effects, the effect of the increase of local temperature and strain, and substitutional and nonstoichiometry effects on the Raman spectra in Ce(Ba,Nd,Gd)O~2~ nanopowders obtained by self‐propagating, room‐temperature synthesis, and silicon nanowires obtained by the electrochemical etching process. The local temperature was monitored by measuring the Stokes/anti‐Stokes peak ratio. We found large wavenumber shifts, up to 10 (30) cm^−1^, and broadenings, up to 40 (20) cm^−1^, of the first‐order Raman‐active modes of Ce(M)O~2~ (n‐Si), which we attribute to confinement and strain effects (laser heating). The phonon softening and phonon linewidth are calculated using a phenomenological model, which takes into account disorder effects through the breakdown of the k = 0 Raman‐scattering selection rule, and also anharmonicity, which is incorporated through the three‐ and four‐phonon anharmonic processes. Very good agreement with experimental data is obtained for the calculated spectra of CeO~2~ with nanograin sizes of about 7 nm, taking into account particle size distribution, as well as an increase in the anisotropy constants with respect to those of bulk materials. Copyright © 2007 John Wiley & Sons, Ltd.