| Autor: |
G. Dezanneau, A. Sin, M. Audier, O. Isnard, H. Roussel, H. Vincent |
| Rok vydání: |
2002 |
| Předmět: |
|
| Zdroj: |
Crystal Engineering. 5:347-354 |
| ISSN: |
1463-0184 |
| DOI: |
10.1016/s1463-0184(02)00046-1 |
| Popis: |
La 1− x MnO 3+ δ ( x =0–0.3) nanopowders were prepared at low temperature (825 °C) from a sol–gel method. As results of chemical analyses and X-ray diffraction of products, two ranges of La/Mn ratios can be distinguished: for La/Mn 0.9 MnO 3 and Mn 3 O 4 occurs while single phases with vacancies on both La and Mn sites are obtained for La/Mn>0.9. La and Mn vacancy concentrations were determined from combined Rietveld refinements of X-ray and neutron diffraction data. Correlations between these structural characteristics and magnetic properties were made. Curie temperatures remain constant at a very high value of 295 K for La/Mn 0.9. The decrease of Curie temperatures can be related to an increasing amount of Mn vacancies up to a limit corresponding to a La 0.93 Mn 0.93 O 3 compound with La/Mn=1. For this compound a cluster–glass behaviour is observed. Finally, neutron diffraction was performed as a function of temperature in order to determine the nature of the magnetic interactions. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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