A new high‐pressure form of KAlSi3O8 under lower mantle conditions
A new high‐pressure form of KAlSi3O8 under lower mantle conditions
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DOI：
10.1029/2004gl021156
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发表时间：
2004-12
影响因子：
5.2
通讯作者：
Yuichiro Sueda;T. Irifune;N. Nishiyama;R. Rapp;T. Ferroir;Tsuyoshi Onozawa;T. Yagi;S. Merkel;N. Miyajima;K. Funakoshi
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文献类型：
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作者：
Yuichiro Sueda;T. Irifune;N. Nishiyama;R. Rapp;T. Ferroir;Tsuyoshi Onozawa;T. Yagi;S. Merkel;N. Miyajima;K. Funakoshi
采用金刚石对顶砧和多对顶砧装置结合同步辐射对KAlSi 3 O 8进行了原位X射线衍射测量。使用不同技术的两种测量都表明，在室温下增加压力时，K-硬硅钙石在22 GPa下转变为新的高压相（硬硅钙石II）。新相的X射线衍射峰基于具有I2/m空间群的单斜晶胞被合理地索引。还证实了在1200°C的高温和35 GPa的压力下形成的硬锰矿II，其在压力下淬火至室温，但在释放压力时在约20 GPa下转化回硬锰矿。目前的结果与主要基于淬火方法的早期研究相矛盾，该研究得出的结论是，在室温和高达2300°C的高温下，在高达95 GPa的压力下，硬锰矿是稳定的。
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.