Heats of transformations in bismuth oxide by differential thermal analysis
- 1 May 1965
- journal article
- Published by National Institute of Standards and Technology (NIST) in Journal of Research of the National Bureau of Standards Section A: Physics and Chemistry
- Vol. 69A (3) , 237-243
- https://doi.org/10.6028/jres.069a.023
Abstract
DTA was chosen as a convenient method for resolving differences in the reported heat of transition and heat of fusion of Bi2O3. The heat of the low to high transition of K2SO4 (at 583 °C) and the heat of fusion of Ag (at 960.8 °C) were used as internal standards. These standards were mixed directly with the Bi2O3 in three weight ratios. The heating schedule for each weight ratio was 3°/min, 9°/min, and 3°/min. For evaluating internal consistency, DTA determinations were made for mixtures of the two standards. Linearity was obtained within limits between the weight ratio of Bi2O3 and standard and the corresponding ratio of peak areas. The heat of transition of Bi2O3 ( mon → 730 ° C cubic was found to be 9.9 ± 0.5 kcal/mole and the heat of fusion ( cubic → 825 ° C liq . ) 3.9 ± 0.2 kcal/mole. The uncertainties are estimated limits of error, based on internal consistency and on the values of the standards.Keywords
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