| Autor: |
Hibino, Toshiyuki, Tsunashima, Atsumu |
| Zdroj: |
Clays and Clay Minerals; December 1997, Vol. 45 Issue: 6 p842-853, 12p |
| Abstrakt: |
The thermal decomposition behavior of hydrotalcite-like compounds (HTlcs) prepared by reconstruction of calcined HTlcs is described. From the results of X-ray diffraction (XRD), it seems that dicarboxylate intercalates of HTlc calcined at 500 °C are completely reconstructed to Mg-Al-CO3HTlc by exposure to aqueous Na2CO3. However, the Mg-Al-CO3HTlc reconstructed under particular conditions yields spinel (MgAl2O4) at 400 °C. This temperature is very low, because Mg-Al-CO3HTlc that has been reported yields spinel at 900 °C after forming a Mg-Al double oxide. The reconstructed Mg-Al-CO3HTlc that yields spinel at 400 °C is obtained when the following conditions are fulfilled: the crystallites of the starting dicarboxylate intercalates are coagulated tightly and the calcined HTlcs and reconstructed materials are not ground. The Mg-Al-CO3HTlc reconstructed under these conditions contains only 55–70% of carbonate anions required by stoichiometry. Therefore, we conclude that the transformation of reconstructed Mg-Al-CO3HTlc to spinel at 400 °C is the result of a reaction occurring between edges of crystallites. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
|
Full text from SpringerLink