Diffusion and reactivity of ZnO-MnO{sub x} system
- Department of Electroceramics, Instituto de Ceramica y Vidrio, CSIC, 28049 Madrid (Spain)
- Advanced Materials Department, Jozef Stefan Institute, Jamova 39, 1000 Ljubljana (Slovenia)
The solid state interaction between ZnO and MnO{sub x} in air was investigated at different temperatures by means of the diffusion couple technique. No diffusion is observed at temperatures below 973 K. Above this temperature, Mn(IV) is already reduced to Mn(III) and the subsequent formation of Mn{sub 2}O{sub 3} impels the diffusion of manganese into the ZnO pellet. However, it never enters the wurtzite lattice, so no homogeneous Mn:ZnO solid solution is formed. Simultaneously, Zn greatly diffuses in the manganese pellet, and as a consequence, a new phase layer develops at MnO{sub x}/reaction zone interface. A mixture of cubic and tetragonal spinel-type phases initially comprises this layer. However at higher temperatures, the tetragonal ZnMn{sub 2}O{sub 4} spinel is the unique phase present in the interface, and it forms a physical barrier for further diffusion of both zinc and manganese species in the respective pellets of the couple. Differences arising between ZnO, MnO{sub 2} and Mn{sub 2}O{sub 3} crystal structures are behind these diffusion behaviors. - Graphical abstract: Penetration profile of Zn into MnO{sub x} pellet after firing the ZnO/MnO{sub x} couple at 973 K for 12 h. The formation of a layer of ZnMn{sub 2}O{sub 4} spinel phase at the surface of MnO{sub x} pellet will impede further diffusion of zinc and manganese species.
- OSTI ID:
- 21043828
- Journal Information:
- Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Journal Issue: 9 Vol. 180; ISSN 0022-4596; ISSN JSSCBI
- Country of Publication:
- United States
- Language:
- English
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