Haines, J., and J. M. Léger. “X-ray diffraction study of the phase transitions and structural evolution of tin dioxide at high pressure: ffRelationships between structure types and implications for other rutile-type dioxides.” Physical Review B 55, no. 17 (1997): 11144.
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SnO2 was investigated at pressures up to 49 GPa by angle-dispersive x-ray diffraction using an imaging plate. Three phase transitions were observed on compression. Rutile-type SnO2 underwent a second-order transition to a CaCl2-type phase at 11.8 GPa under hydrostatic conditions, as determined from the pressure dependence of the spontaneous strain. This transition was observed at significantly lower pressures under nonhydrostatic conditions. A second transition to an α-PbO2-type phase was observed to begin above 12 GPa under nonhydrostatic conditions; however, only a small amount of this phase was obtained. Both the α-PbO2-type and the CaCl2-type phases transformed to a modified fluorite-type phase, space group Pa3-bar, above 21 GPa. Upon decompression, retransformation was observed and the sample recovered under ambient conditions consisted of a mixture of the rutile-type and α-PbO2-type phases. The structures of the rutile, CaCl2 and modified fluorite type phases were refined in situ by the Rietveld method allowing the structural evolution of SnO2 to be followed as a function of pressure. The relationships between the high-pressure structures of SnO2 are discussed using group theory and potential transformation pathways identified. The transition sequence observed for tin dioxide has important implications for the high-pressure behavior of other rutile-structured compounds.