High-pressure-induced metastable phase in tetragonal 2D polymeric C-60

The structural stability of the tetragonal two-dimensional (2D) polymeric p hase of C-60 has been studied under pressure up to similar to 24 GPa and ro om temperature by means of in situ Raman scattering. An irreversible transf ormation of the material to a new phase was observed at pressure similar to 20 GPa. The phonon spectrum of the high-pressure phase provides a strong i ndication that the fullerene molecular cage is retained and therefore this phase may be related to a three-dimensional (3D) network of C-60 cages. The new phase remains stable upon slow release of pressure to ambient conditio ns. The recovered material is metastable and transforms in air by detonatio n under laser irradiation to partially dimerized C-60 (C) 2001 Elsevier Sci ence B.V. AH rights reserved.