On the Sintering of Stannic oxide : (I) Influence of Addition of Bismuth Oxide

概要

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The isothermal shrinkage of the compacts of stannic oxide powders containing 0, 1, 3 and 5 mol % of bismuth was measured by means of a shrinkage meter between 1150° and 1250 °C in air. The shrinkage rate of stannic oxide powder was very small and its activation energy was calculated as 38 Kcal/mol. By the addition of bismuth, the shrinkage was found to be increased. By the addition of 1-3 mol % of bismuth, no change in the lattice constant was observed from the X-ray analysis. Therefore it may be considered that bismuth ion is soluble in SnO2 up to 3 mol % and is substituted for Sn +in SnO2. Assuming that bismuth in SnO2 is trivalent state this substitution will increase the concentration of oxygen vacancy. Hence the diffusion of ions is promoted, as a result, the shrinkage rate of compact is accelerated. The compound Bi2(SnO3) 3 was detected in the compact containing 5 mol % of bismuth by X-ray analysis. The presence of Bi2(SnO3) 3 decreases the shrinkage rate during sintering.
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