Effect of preparation procedure on redox states of iron in soda-lime silicate glass

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• 作者：Masaru Yamashita ; Tomoko Akai ; Ryosuke Sawa ; Junko Abe ; Michio Matsumura
• 关键词：Electrochemical properties ; Oxidation reduction ; Chemical activity ; Absorption ; Soda-lime silica
• 刊名：Journal of Non-Crystalline Solids
• 出版年：2008
• 出版时间：15 October 2008
• 年：2008
• 卷：354
• 期：40-41
• 页码：4534-4538
• 全文大小：205 K

文摘

The redox state of iron in soda-lime silicate glass was determined by analysis of the optical absorption bands due to Fe²⁺ and Fe³⁺ states. When raw materials containing Fe₂O₃ were heated gradually to 1400 °C, the total-Fe content of the glass was 9.4 % Fe²⁺, but rapid heating at 1400 °C increased the Fe²⁺ content to 11.7 % . The oxygen activity (aO₂) in the corresponding melts was measured using zirconia and Pt electrodes. The value increased with increasing temperature in the gradually heated sample and reached log(aO₂) = 0.03 at 1400 °C, but was about 2.5 times lower in the rapidly heated sample at log(aO₂) = −0.37. After SnO addition to the raw material, oxygen activity depended strongly on heating speed: log(aO₂) at 1400 °C fell as low as −1.8 with rapid temperature increase but was about −0.2 or higher with gradual heating. The Fe²⁺ content of the cooled glass was consistent with the oxygen activity of the melts. The effect of heating speed was attributed to the formation of a melt layer on the surface of the raw material.