Abstract
The reaction between BaCO3 and GeO2 has been studied in air and in CO2 at 800-1000°C. Several products (Ba2GeO 4, BaGeO 3 and BaGe4O9) were obtained when the mixtures of BaCO3 and GeO2 were heated in air, but under the CO2 atmosphere of 393-763mmHg, Ba2GeO 4 was prepared with very small amounts of BaGeO3 and BaGe4O9 so far as BaCO3 was remaining in the samples.
The kinetics of the following reaction were studied under the CO2 atmosphere of 763 mmHg.
2BaCO3+GeO2=Ba2GeO4+2CO2
The kinetic data can be expressed reasonably by the zero-order equation. There is a discontinuity in the plotting of log k against 1/T at about 830°C or 840°C for the reaction of BaCO3 with hexagonal GeO2, or with tetragonal GeO2, respectively. The values of activation energy are about 37 or 16 kcal/mol above or below 830°C, respectively, for the reaction of BaCO3 with hexagonal GeO2, and 65 or 22 kcal/mol above or below 840°C, respectively, for the reaction with tetragonal GeO2. The kinetic data are discussed in comparison with the kinetic dada for the reaction between BaCO3 and TiO2 under the atmosphere of CO2.
