Accession Number : ADA266399


Title :   Structural Studies of Sol-Gel Glasses


Descriptive Note : Final rept. 15 Jul 1989-14 Jul 1992


Corporate Author : BRUNEL UNIV UXBRIDGE (UNITED KINGDOM)


Personal Author(s) : Perry, Carole C


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a266399.pdf


Report Date : 14 Jul 1992


Pagination or Media Count : 8


Abstract : The research objectives were to relate sol-gel microscopic structural chemistry and Structural chemistry and silica surface chemistry to the sol-gel process. Detailed studies have been carried out on silica, silica/titania, Co (2+) Nd (3+), dye (RG6) doped silica gel-glasses and Sn-Si-O gels. Major conclusions are; (1) On thermal treatment, the gel-glass matrix is strengthened by bond shortening, and a reduction in mean Si-O-S bond angle and angular distribution for this feature. (2) The incorporation of low levels of titanium lead to more disordered glasses and the addition of tin into the silica matrix enhances the densification process and reduces the thermal treatment temperature by ca. 300 deg C necessary to remove hydroxyl groups from the surfaces of the gels. (3) Four different water species can be identified on gel-glass surfaces with associated species being formed before completion of the first monolayer. Increasing hydrophobicity for samples at high temperature is attributed to the low concentration of surface silanol groups present and their reduced activity. (4) Cobalt, neodymium and dye (PG6) post-doped homogeneous classes (for lasing action) were produced. The coordination chemistry of the metal ions depends on the nature of the metal ions and ligands, thermal history and composition of the glass. The silanol groups only play a major role in coordination with the metal ions after sintering. The incorporation of the dye in to the gel-glass matrix results In specific interactions between the glass and the dye and a marked reduction in water content of the glass.... Sol-gel glasses, Co (2+) Doped glasses, Nd (3+) Doped glasses, RG6 Doped glasses, Sn-Si-O-gels, FTIR spectroscopy, NIR Spectroscopy, UV-VIS Spectroscopy, N2 Adsorption, FT Raman spectroscopy


Descriptors :   *GLASS , *SILICA GELS , FOURIER TRANSFORMATION , ANGLES , IONS , METALS , OPTICAL PROPERTIES , TEMPERATURE , INFRARED SPECTROSCOPY , REDUCTION , TITANIUM , TIN , VISIBLE SPECTRA , LIGANDS , SILICON , ULTRAVIOLET SPECTROSCOPY , CHEMISTRY , CHEMICAL BONDS , OXYGEN , SINTERING , DISPERSIONS , COBALT , HYDROPHOBIC PROPERTIES , GELS , COLLOIDS , NEODYMIUM , MEAN , SULFUR , DYES , DOPING , SURFACE CHEMISTRY , SPECTROSCOPY , DISTRIBUTION , INTERACTIONS , WATER , ADSORPTION , HIGH TEMPERATURE , RAMAN SPECTROSCOPY


Subject Categories : Inorganic Chemistry
      Physical Chemistry
      Atomic and Molecular Physics and Spectroscopy


Distribution Statement : APPROVED FOR PUBLIC RELEASE