ISSN:
0001-1541
Keywords:
Chemistry
;
Chemical Engineering
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Process Engineering, Biotechnology, Nutrition Technology
Notes:
The kinetics of binaty mixtures of Y2O3 - BaCO3-CuO (Ba-Cu) and Y2O3 -CuO(Y-Cu) prepared by citrate sot-gel techniques were studied in both air and helium. Particle sizes resulting from the sol - gel preparation were between 5 and 100 nm, and the prevailing kinetics differed significantly from those observed in the companion study of micron-sized particles. That is, nucleation-growth kinetics of the Avrami-Erofe'eu type adequately model the kinetics over the entire conversion range as opposed to the diffusion mechanisms that describe the kinetics in larger sized particles. An alternate nucleation-growth model, which neglects overlapping volumes during reaction (Austin - Rickett model), was also adequate in the Ba-Cu system where particle size/spacing was larger, but was only applicable in other reaction systems at lower conversions. Activation energies obtained from the Avrami- Erofe'ev were consistently lower than those from the Austin - Rickett model, because the former model contains two parameters that are temperature-sensitive.
Additional Material:
9 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/aic.690410714
