Synthesis of a new high-pressure ohase of tin dioxide and some geophysical implications |
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Authors: | Lin-Gun Liu |
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Institution: | Research School of Earth Sciences Australian National University Canberra, A.C.T. Australia |
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Abstract: | Tin dioxide (SnO2) in the rutile structure as starting material has been found to transform to the orthorhombic α-PbO2 structure (S.G. Pbcn) at about 155 kbar and 1000–1400°C when compressed in a diamond-anvil cell and heated by irradiation with a YAG laser. The lattice parameters at room temperature and 1 bar are for the orthorhombic form of SnO2, which is 1.5% more dense than the rutile form. Crystal-chemical arguments suggest that stishovite (SiO2) may also transform to the α-PbO2 structure at elevated pressure and temperature with an increase in zero-pressure density of about 2–3%. Mineral assemblages containing the orthorhombic SiO2 are unstable relative to those containing the perovskite MgSiO3 under lower-mantle conditions. |
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