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The pyrite-type high-pressure form of silica

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The x-ray diffraction with the use of the DAC/LH (diamond anvil cell / laser-heating) system is a powerful technique to study in-situ structural observations of materials under high-pressure/temperature. Using this technique, one can observe the crystal structures of the mantle minerals or materials of the core under the inner-earth/planets condition. The figure shows the pyrite-type form of Silica (SiO2) at the condition of 268 GPa/1800K, and its phase diagram. These data reveal the fact that the silicon coordination number increases from 4 or 6 in the lower pressure phase to 6+2 in the pyrite-type (Y. Kuwayama et al., Science, 309(2005)923).

Figure. Pyrite-type form of silica and phase diagram.

[ Y. Kuwayama, K. Hirose, N. Sata and Y. Ohishi, Science 309, 923-925 (2005), Fig. 3, 4,
©2005 American Association for the Advancement of Science ]

 

Scientific keywords

A. Sample category inorganic material
B. Sample category (detail) insulator, ceramics, crystal, mineral,rock
C. Technique X-ray diffraction
D. Technique (detail) powder diffraction
E. Particular condition microbeam (> 10 µm), high pressure (DAC), high-T (> 500 C)
F. Photon energy X-ray (4-40 keV)
G. Target information crystal structure, phase transition

Industrial keywords

level 1---Application area Semiconductor, Chemical product, industrial material
level 2---Target silicon semiconductor, catalysis, glass
level 3---Target (detail) gate insulator, interlayer insulator, capacitance insulator
level 4---Obtainable information density, crystal structure, elastic modulus
level 5---Technique diffraction

Inquiry number

SOL-0000001075

Last modified 2006-03-30 11:11
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