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Phase formation mechanism and kinetics in solid-state synthesis of undoped and calcium-doped lanthanum manganite
- Source :
-
Materials Research Bulletin . Mar2009, Vol. 44 Issue 3, p649-653. 5p. - Publication Year :
- 2009
-
Abstract
- Abstract: LaMnO3+δ and La0.7Ca0.3MnO3 were synthesized from La2O3(La(OH)3), CaCO3 and MnO2 powder mixture with solid-state reaction technique. X-ray diffraction and thermal analysis were employed in the present study on the process of synthesizing of the two compound powders. The kinetic study on solid-state reaction between La2O3 and MnO2 in the powder mixture was isothermally carried out for LaMnO3+δ formation. The result showed that the reaction process was controlled by three-dimensional solid-ionic diffusion. Both Jander and Ginstling-Brounstein model can be used to describe the reaction kinetics satisfactorily. The relevant apparent activation energy values obtained were as great as 205±11 and 189±8kJ/mol. The reaction process of La0.7Ca0.3MnO3 preparation from La2O3, SrCO3 and MnO2 powder mixture was also studied using X-ray diffraction and thermal analysis. The result indicated that the following steps composed the overall reaction: the decomposition of the reactant; the formation of La1−x Ca x MnO3+δ ; La2O3 and Mn3O4 reacted with La1−x Ca x MnO3 to form final La0.7Ca0.3MnO3 phase. The latest step was the most time-consuming one among others in the overall reaction. [Copyright &y& Elsevier]
Details
- Language :
- English
- ISSN :
- 00255408
- Volume :
- 44
- Issue :
- 3
- Database :
- Academic Search Index
- Journal :
- Materials Research Bulletin
- Publication Type :
- Academic Journal
- Accession number :
- 36341332
- Full Text :
- https://doi.org/10.1016/j.materresbull.2008.06.022