Optical and Acoustic Vibrations Confined in Anatase TiO₂ Nanoparticles under High-Pressure

Lucien Saviot (1) , Denis Machon (2) , L. Debbichi (1) , Adrien Girard (2) , Jeremie Margueritat (2) , Peter Krüger (1) , Maria del Carmen Marco de Lucas (1) , Alain Mermet (2)

1 ICB - Laboratoire Interdisciplinaire Carnot de Bourgogne
2 ILM - Institut Lumière Matière [Villeurbanne]

The effect of an applied high pressure on the optical and acoustic vibrations of small anatase TiO₂ nanoparticles is studied using Raman scattering. All the Raman peaks show a significant variation of their frequency with pressure, except for the low-frequency peak which is due to acoustic vibrations confined in the nanoparticles. These variations (or lack thereof) are compared to first-principles calculations of the stiffness tensor and phonons of bulk anatase TiO₂ as a function of pressure. In particular, the variation of the shape of the low-frequency peak is explained by the increase of the elastic anisotropy of anatase TiO₂ as pressure is increased.

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Lucien Saviot, Denis Machon, L. Debbichi, Adrien Girard, Jeremie Margueritat, et al.. Optical and Acoustic Vibrations Confined in Anatase TiO₂ Nanoparticles under High-Pressure. Journal of Physical Chemistry C, 2014, 118 (19), pp.10495. ⟨10.1021/jp502409e⟩. ⟨hal-00991336⟩