High-pressure behavior of sillimanite and kyanite: Compressibility, decomposition and indications of a new high-pressure phase
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Alexandra Friedrich
Abstract
The high-pressure behavior of the two Al2SiO5 polymorphs sillimanite and kyanite was investigated up to 46 and 53 GPa, respectively, using a diamond-anvil cell and powder X-ray synchrotron diffraction. The bulk moduli of sillimanite and kyanite obtained from a fit to a second-order Birch-Murnaghan equation of state are B0 = 176(11) GPa and B0 = 190(3) GPa at fixed B′ = 4, respectively. The samples were laser annealed several times at high pressures. After laser annealing at 46 GPa, sillimanite was decomposed into its oxide components corundum (Al2O3) and stishovite (SiO2). The high-pressure behavior of kyanite, however, is more complicated. Up to 20 GPa, kyanite remains stable. At 30 GPa a new high-pressure form is observed, which seems to be structurally related to kyanite. After laser heating, it partly decomposed into corundum and stishovite. However, when laser heating at much higher pressures of 47 to 53 GPa, the new phase remains stable.
© 2004 Oldenbourg Wissenschaftsverlag GmbH
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Articles in the same Issue
- Editorial: High-Pressure Crystallography and Synthesis
- New pressure cell for single-crystal X-ray investigations on diffractometers with area detectors
- High-pressure and high-temperature powder diffraction on molybdenum diphosphide, MoP2
- The effects of pressure, temperature and composition on the crystal structures of α-quartz homeotypes
- High-pressure behavior of sillimanite and kyanite: Compressibility, decomposition and indications of a new high-pressure phase
- Multianvil high-pressure / high-temperature synthesis in solid state chemistry
- Putting the squeeze on NaCl: modelling and simulation of the pressure driven B1-B2 phase transition
- Mechanism of the pressure induced reconstructive transformation of KCl from the NaCl type to the CsCl type structure
- Ab initio investigations of TlI-type compounds under high pressure
- Polymorphic forms of Rb2Te: in-situ high-pressure DAC X-ray diffraction investigations and structure modelling with CASTEP
- Electronic structure and bonding in antimony and its high pressure phases
- Metallic high-pressure modifications of main group elements
