Pressureinduced structural evolution of pyritety

Authors: Yasuhiro Kuwayama Kei Hirose Nagayoshi Sata Yasuo Ohishi

Publish Date: 2011/04/28

Volume: 38, Issue: 8, Pages: 591-597

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Abstract

The equation of state and pressureinduced structural evolution of pyritetype SiO2 have been investigated based on synchrotron Xray diffraction measurements in a diamondanvil cell The Rietveld refinement revealed that the oxygen coordinate x of pyritetype SiO2 increases with increasing pressure The SiO6 coordination polyhedra of pyritetype SiO2 is less compressible than the unit cell and the increase in x induces a rotation of the SiO6 coordination polyhedra to fill the blank space in the unit cell Thus the volume reduction in pyritetype SiO2 is achieved mainly by the rotation of the SiO6 polyhedra rather than by the compression of the SiO6 polyhedra In addition the increase in x with increasing pressure enhances a distortion of the coordination polyhedra of pyritetype SiO2 implying that pyritetype SiO2 is not likely to transform into a fluoritetype structure at higher pressuresThe authors thank K Fujino H Hirai T Tsuchiya Y Tatsumi H Ohfuji Y Tange and S Whitaker for helpful discussions and support We acknowledge A R Oganov and N Funamori for their constructive reviews In situ XRD measurements were conducted at SPring8 proposal no 2005A5013LD2np 2005B0099 and 2006A0099 Y K was supported by the JSPS Research Fellowships for Young Scientists

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