Pressure-induced polyamorphism in TiO2 nanoparticles

D. Machon (1) , M. Daniel (2) , V. Pischedda (1) , S. Daniele (2) , P. Bouvier (3) , S. Lefloch (1)

1 LPMCN - Laboratoire de Physique de la Matière Condensée et Nanostructures
2 IRCELYON - Institut de recherches sur la catalyse et l'environnement de Lyon
3 LMGP - Laboratoire des matériaux et du génie physique

Two different nanometric (6 nm) TiO2 compounds, anatase polycrystals and amorphous particles, were investigated under high pressure using Raman spectroscopy. Nanoanatase undergoes a pressure-induced amorphization. The pressure-induced transformations of this mechanically prepared amorphous state are compared with those of a chemically prepared amorphous particles. In the mechanically prepared amorphous state, a reversible transformation from a low-density amorphous state to high-density amorphous state (HDA1) is observed in the range 13-16 GPa. In the chemically prepared sample, a transformation to a new high-density amorphous state (HDA2) is observed at around 21 GPa. Further compression leads to the transformation HDA2 -> HDA1 at similar to 30 GPa. We demonstrate that depending on the starting amorphous material, the high-pressure polyamorphic transformations may differ. This observation indicates that pressure is a suited tool to discriminate between nanomaterials apparently similar at ambient conditions.

Domains: Catalysis; Environment and Society

D. Machon, M. Daniel, V. Pischedda, S. Daniele, P. Bouvier, et al.. Pressure-induced polyamorphism in TiO2 nanoparticles. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2010, 82 (140102), pp.1-4. ⟨10.1103/PhysRevB.82.140102⟩. ⟨hal-00537365⟩