| Autor: |
Isupova, L., Tsybulya, S., Kryukova, G., Alikina, G., Boldyreva, N., Vlasov, A., Snegurenko, O., Ivanov, V., Kolomiichuk, V., Sadykov, V. |
| Zdroj: |
Kinetics & Catalysis; Jan2002, Vol. 43 Issue 1, p129-138, 10p |
| Abstrakt: |
The phase composition of La1 – xCa xFeO3 – 0.5 x perovskites synthesized from preactivated oxides was studied by powder X-ray diffraction analysis and differential dissolution. The system does not form a continuous series of homogeneous solid solutions. No intermediate samples from this series are monophasic. It was found that the synthesis under nonequilibrium conditions (mechanical activation + calcination at 900°С for 4 h) resulted in nonequilibrium microheterogeneous solid solutions with degrees of calcium substitution for lanthanum of no higher than 0.5. A longer calcination (for 16 h) or an increase in the calcination temperature of solutions up to 1100 °С decreased the calcium content of the samples down to x ∼ 0.2 because of the formation of a brownmillerite phase. The catalytic activity of the test samples in the oxidation of CO changed nonmonotonically with x, and it was maximum at x = 0.5–0.6, which correlates with the maximum density of interphase boundaries in these samples. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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