Some clues about the interphase reaction between ZnO and MnO{sub 2} oxides

Raman spectroscopy is used to evidence both the nature of the interphase reaction between ZnO and MnO{sub 2} particles and its kinetic evolution. Zn cations migrate from the ZnO grains during oxygen vacancies formation process and diffuse into the MnO{sub 2} particles leading to an interphase region...

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Bibliographic Details
Published in:Journal of solid state chemistry 2009-05, Vol.182 (5)
Main Authors: Rubio-Marcos, F., Quesada, A., Insituto de Ciencia de Materiales de Madrid, CSIC, 28049 Madrid, Departamento de Fisica de Materiales, UCM, 28040 Madrid, Garcia, M.A., Banares, M.A., Fierro, J.L.G., Martin-Gonzalez, M.S., Costa-Kraemer, J.L., Fernandez, J.F.
Format: Article
Language:English
Subjects:
CHALCOGENIDES
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DIFFUSION
HEAT TREATMENTS
INTERFACES
INTERMEDIATE STATE
LASER SPECTROSCOPY
MAGNETIC PROPERTIES
MAGNETISM
MANGANESE COMPOUNDS
MANGANESE OXIDES
MATERIALS SCIENCE
MINERALS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
POINT DEFECTS
RAMAN SPECTROSCOPY
REACTIVITY
SPECTROSCOPY
SPINELS
TEMPERATURE RANGE
TEMPERATURE RANGE 0273-0400 K
TRANSITION ELEMENT COMPOUNDS
VACANCIES
VALENCE
ZINC COMPOUNDS
ZINC OXIDES
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Summary:Raman spectroscopy is used to evidence both the nature of the interphase reaction between ZnO and MnO{sub 2} particles and its kinetic evolution. Zn cations migrate from the ZnO grains during oxygen vacancies formation process and diffuse into the MnO{sub 2} particles leading to an interphase region with an intermediate valence Mn{sup +3}-O-Mn{sup +4}. Large amounts of desorbed Zn cations promote the formation of ZnMn{sub 2}O{sub 4} structure, in addition to the intermediate valence state. The system evolves towards complete formation of the spinel phase at higher thermal treatment times. The reactivity of the ZnO plays an important role in the formation of this interphase. Low-reactivity ZnO powder, in which the oxygen vacancies are previously produced, shows a stabilization of the intermediate valence state with very limited formation of the spinel phase. A clear correlation between the amount of the intermediate state interphase and the magnetic properties has been established. - Graphical abstract: Recently new room temperature interphase magnetism has been reported to appear in ZnO-MnO{sub 2} system. Raman spectroscopy is used to evidence both the nature of the interphase reaction and the kinetic. The interphase evolved towards complete formation of the spinel phase. The reactivity of the ZnO plays an important role in the formation of this interphase. Finally, a clear correlation between the amount of the intermediate valence state and the interphase magnetic properties has been established.
ISSN:0022-4596
1095-726X
DOI:10.1016/j.jssc.2009.02.009