The high-pressure behavior of SnO 2 nanoparticles (∼2.8 nm) was studied up to approximately 20 GPa using Raman spectroscopy in a diamond anvil cell and ab initio simulations. Above ∼7 GPa, the disordering, initially located at the surface, was found to propagate to the core of nanoparticles, ultimately leading to amorphous-like spectra. This observation can be interpreted as a disordering of the oxygen sublattice sensitively probed by Raman spectroscopy in contrast to powder X-ray diffraction techniques. The low-frequency mode can be related to the nanoparticle vibration as an elastic isotropic sphere motion. The pressure-induced shift of this mode allows for the constraining of the mechanical properties data reported in the literature.
SnO_{2} powders and single crystal have been studied under high pressure using Raman spectroscopy and ab initio simulations. The pressure-induced changes are shown to drastically depend on the form of the samples. The single crystal exhibits phase transitions as reported in the literature, whereas powder samples show a disordering of the oxygen sublattice in the first steps of compression. This behavior is proposed to be related to the defect density, an interpretation supported by ab initio simulations. The link between the defect density and an amorphouslike Raman signal is discussed in terms of the invasive percolation of the anionic sublattice. The resistance of the cationic sublattice to the disorder propagation is discussed in terms of cation close packing. This result on SnO_{2} may be extended to other systems and questions a "traditional" crystallographic description based on polyhedra packing, as a decoupling between both sublattices is observed.
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