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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Effects of solid solution on the high-low inversion of cristobalite and the stabilization of high cristobalite

Sun, Tawei January 1989 (has links)
The inversion temperature of cristobalite was investigated by incorporating TiO₂, AlPO₄, and BPO₄ into the cristobalite phase using solid state reactions. The combination of TiO₂ and AlPO₄ proved to be most effective in lowering the inversion temperature of cristobalite. Phase diagrams at the high silica corner were constructed for the respective systems. High cristobalite was stabilized for compositions prepared from the CaO-Al2₂O₃-SiO₂ and CuO-Al₂O₃-SiO₂ system using sol-gel processing. The stabilization mechanism is attributed to the surface energy effect resulting from the formation of fine crystals. The structural evolution from the x-ray amorphous gel to high cristobalite was examined by FTIR and Raman spectroscopy. The thermal expansion of the stabilized high cristobalite was characterized by high temperature x-ray. Changes in bond angle continue to dominate the thermal expansion of high cristobalite. / Ph. D.

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