A new high-pressure form of Ka1Si 3 O 8 under lower mantle conditions
In situ X-ray diffraction measurements have been made on KAlSi3O8 hollandite using diamond anvil cell and multianvil apparatus combined with synchrotron radiation. Both of the measurements with different techniques demonstrated that K-hollandite transforms to a new high-pressure phase (hollandite II) at ∼22 GPa upon increasing pressure at room temperature. The X-ray diffraction peaks of the new phase were reasonably indexed on the basis of a monoclinic cell with I2/m space group. Hollandite II was also confirmed to be formed at high temperatures to 1200°C and pressures to 35 GPa, which was que... Mehr ...
Verfasser: | |
---|---|
Dokumenttyp: | Journal article |
Verlag/Hrsg.: |
American Geophysical Union
|
Schlagwörter: | Keywords: Diamonds / Synchrotron radiation / Thermal effects / X ray diffraction analysis / Diamond anvil cells / High-pressure form / Hollandite / Quench method / Silicon compounds / diamond anvil cell / lower mantle / X-ray diffraction 1025 Geochemistry: Composition of the mantle / 3630 Mineralogy and Petrology: Experimental mineralogy and petrology / 3675 Mineralogy and Petrology: Sedimentary petrology / 3924 Mineral Physics: High-pressure behavior / 3954 Mineral Physics: X ray / neutron / and electron spectroscopy and diffraction |
Sprache: | unknown |
Permalink: | https://search.fid-benelux.de/Record/base-27511512 |
Datenquelle: | BASE; Originalkatalog |
Powered By: | BASE |
Link(s) : | http://hdl.handle.net/1885/52683 |
In situ X-ray diffraction measurements have been made on KAlSi3O8 hollandite using diamond anvil cell and multianvil apparatus combined with synchrotron radiation. Both of the measurements with different techniques demonstrated that K-hollandite transforms to a new high-pressure phase (hollandite II) at ∼22 GPa upon increasing pressure at room temperature. The X-ray diffraction peaks of the new phase were reasonably indexed on the basis of a monoclinic cell with I2/m space group. Hollandite II was also confirmed to be formed at high temperatures to 1200°C and pressures to 35 GPa, which was quenched to room temperature under pressure but converted back to hollandite at about 20 GPa on release of pressure. The present result is contradictory to earlier studies based mainly on quench method, which concluded that hollandite is stable up to 95 GPa at both room temperature and high temperatures up to 2300°C.