Pressure-Induced Structural Phase Transition of Co-Doped SnO2 Nanocrystals

Co-doped SnO2 nanocrystals (with a particle size of 10 nm) with a tetragonal rutile-type (space group P4(2)/mnm) structure have been investigated for their use in in situ high-pressure synchrotron angle dispersive powder X-ray diffraction up to 20.9 GPa and at an ambient temperature. An analysis of experimental results based on Rietveld refinements suggests that rutile-type Co-doped SnO2 undergoes a structural phase transition at 14.2 GPa to an orthorhombic CaCl2-type phase (space group Pnnm), with no phase coexistence during the phase transition. No further phase transition is observed until 20.9 GPa, which is the highest pressure covered by the experiments. The low-pressure and high-pressure phases are related via a group/subgroup relationship. However, a discontinuous change in the unit-cell volume is detected at the phase transition; thus, the phase transition can be classified as a first-order type. Upon decompression, the transition has been found to be reversible. The results are compared with previous high-pressure studies on doped and un-doped SnO2. The compressibility of different phases will be discussed.

Automated summary

In this study, Co-doped SnO2 nanocrystals with a tetragonal rutile-type structure were subjected to high-pressure conditions up to 20.9 GPa. It was found that the Co-doped SnO2 undergoes a structural phase transition to an orthorhombic CaCl2-type phase at 14.2 GPa, with no phase coexistence. A discontinuous change in the unit-cell volume was observed during the phase transition, indicating a first-order type phase transition. Upon decompression, the transition was found to be reversible. The results were compared with previous studies on doped and un-doped SnO2, and the compressibility of different phases was discussed.