Some clues about the interphase reaction between ZnO and MnO2 oxides
2009; Elsevier BV; Volume: 182; Issue: 5 Linguagem: Inglês
10.1016/j.jssc.2009.02.009
ISSN1095-726X
AutoresFernando Rubio‐Marcos, A. Quesada, M. A. Garcı̀a, Miguel Á. Bañares, J.L.G. Fierro, Marisol Martín‐González, J. L. Costa‐Krämer, J.F. Fernández,
Tópico(s)Magnetic and transport properties of perovskites and related materials
ResumoRaman spectroscopy is used to evidence both the nature of the interphase reaction between ZnO and MnO2 particles and its kinetic evolution. Zn cations migrate from the ZnO grains during oxygen vacancies formation process and diffuse into the MnO2 particles leading to an interphase region with an intermediate valence Mn+3–O–Mn+4. Large amounts of desorbed Zn cations promote the formation of ZnMn2O4 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.
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