| Autor: |
Nishida, Tetsuaki, Hirai, Toshiharu, Takashima, Yoshimasa |
| Zdroj: |
Bulletin of the Chemical Society of Japan; December 1981, Vol. 54 Issue: 12 p3735-3738, 4p |
| Abstrakt: |
The Mössbauer technique at the liquid nitrogen temperature (78 K) was applied to the estimation of nonbridging oxygens in FeO4, BO4, and SiO4units in potassium borosilicate glasses. Mössbauer spectra consist of a quadrupole doublet and a hyperfine structure due to Fe3+ions with tetrahedral symmetry. The hyperfine structure is attributed to a relaxation effect because magnetic susceptibility measurements revealed the glasses to be paramagnetic in the temperature range 78–295 K. A linear decrease in the absorption area and a similar decrease in the internal magnetic field for the hyperfine structure were observed with an increase in the alkali content of glasses. The decrease is ascribed to a formation of non-bridging oxygen at the site adjacent to iron, because the mean life-time of the internal magnetic field produced by 3d-electrons of iron is considered to decrease with increasing thermal vibration of the iron and neighboring oxygens. Fractions of non-bridging oxygens obtained from the reduction rate of the absorption area of hyperfine structure are in good agreement with earlier results for borate glasses with the same K2O/B2O3ratios, in the alkali region of 8–20 mol% where the borosilicate glasses are essentially considered to be borate glasses diluted with SiO2. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
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