Structural Evolution of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow><mml:mi>SiO</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:math> Glass with Si Coordination Number Greater than 6

Abstract

Pair distribution function measurement of SiO_{2} glass up to 120 GPa reveals changes in the first-, second-, and third-neighbor distances associated with an increase in Si coordination number C_{Si} to >6 above 95 GPa. Packing fractions of Si and O determined from the first- and second-neighbor distances show marked changes accompanied with the structural evolution from C_{Si}=6 to >6. Structural constraints in terms of ionic radius ratio of Si and O, and ratio of nonbonded radius to bonded Si─O distance support the structural evolution of SiO_{2} glass with C_{Si}>6 at high pressures.

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