Premium
A new high‐pressure form of KAlSi 3 O 8 under lower mantle conditions
Author(s) -
Sueda Yuichiro,
Irifune Tetsuo,
Nishiyama Norimasa,
Rapp Robert P.,
Ferroir Tristan,
Onozawa Tsuyoshi,
Yagi Takehiko,
Merkel Sebastien,
Miyajima Nobuyoshi,
Funakoshi Kenichi
Publication year - 2004
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2004gl021156
Subject(s) - hollandite , monoclinic crystal system , x ray crystallography , synchrotron radiation , diffraction , materials science , high pressure , synchrotron , diamond anvil cell , mineralogy , phase (matter) , analytical chemistry (journal) , crystallography , chemistry , optics , crystal structure , thermodynamics , physics , organic chemistry , chromatography
In situ X‐ray diffraction measurements have been made on KAlSi 3 O 8 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 I 2/ 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.