کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1518815 | 1511626 | 2006 | 8 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Preparation and thermal decomposition studies of l-tyrosine intercalated MgAl, NiAl and ZnAl layered double hydroxides Preparation and thermal decomposition studies of l-tyrosine intercalated MgAl, NiAl and ZnAl layered double hydroxides](/preview/png/1518815.png)
l-Tyrosine (represented as l-Tyr) intercalated MgAl, NiAl and ZnAl layered double hydroxides (LDHs) have been obtained by the method of coprecipitation. In situ FT-IR, in situ HT-XRD and TG-DTA measurements allow a detailed understanding of the thermal decomposition process for the three intercalated composites. In situ HT-XRD reveals that the layered structure of l-Tyr/MgAl-LDH collapses completely at 450 °C with the first appearance of reflections of a cubic MgO phase, while the corresponding temperature for l-Tyr/NiAl-LDH is some 50 °C lower. In contrast, there is a major structural change in l-Tyr/ZnAl-LDH at 250 °C as shown by the disappearance of its (0 0 6) and (0 0 9) reflections at this temperature accompanied by the appearance of reflections of ZnO. In situ FT-IR experiments give information about the decomposition of the interlayer -Tyr ions. The decomposition temperature of l-Tyr in the ZnAl host is about 50 °C lower than the corresponding values for the MgAl and NiAl hosts. TG-DTA curves show a significant weight loss step (170–260 °C) in l-Tyr/ZnAl-LDH which is due to the dehydroxylation of the host layers, with a corresponding weak endothermic peak at 252 °C. This temperature range is much lower than that observed for MgAl and NiAl hosts, indicating that the ZnAl-LDH layers are relatively unstable. The data indicate that the order of thermal stability of the three intercalates is: l-Tyr/MgAl-LDH > l-Tyr/NiAl-LDH > l-Tyr/ZnAl-LDH.
Journal: Journal of Physics and Chemistry of Solids - Volume 67, Issue 7, July 2006, Pages 1469–1476