Thermal diffusivity of silica glass at pressures up to 9 GPa |
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| Authors: | Tomoo Katsura |
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| Institution: | 1. Bayerisches Geoinstitut, Universit?t Bayreuth, Postfach 101251, W-8580, Bayreuth, Germany
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| Abstract: | The thermal diffusivity of silica glass was measured at pressures up to 9 GPa and temperatures up to 1200 K. The measurements involve adopting the Ångström method to a cylindrical geometry in a uniaxial split-sphere apparatus. This method can be used to determine thermal diffusivity in samples with dominant conductive heat transfer. The thermal diffusivity of silica glass has a negative first pressure derivative but a positive second pressure derivative. Although the elastic moduli have minima near 3 GPa, the thermal diffusivity does not has minimum up to 9 GPa, which cannot be explained by the model of Kittel (1949). The negative pressure derivative of thermal diffusivity is a feature probably unique in silica glass, and its magnitude should decrease with the addition of Na2O. |
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