Rock Salt−Spinel Structural Transformation in Anodically Electrodeposited Mn−Co−O Nanocrystals
详细信息 查看全文
- 作者：Weifeng Wei ; Weixing Chen ; Douglas G. Ivey
- 刊名：Chemistry of Materials
- 出版年：2008
- 出版时间：March 11, 2008
- 年：2008
- 卷：20
- 期：5
- 页码：1941 - 1947
- 全文大小：827K
- 年卷期：v.20,no.5(March 11, 2008)
- ISSN：1520-5002
文摘
Mn−Co−O nanocrystals, with a defective rock salt-type structure, were prepared by anodic electrodeposition. The structural and chemical stability of the as-deposited oxide nanocrystals were investigated using wavelength dispersive spectroscopy (WDS), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The rock salt−spinel structural transformation occurred in the oxide nanocrystals annealed at a temperature of 500 °C. A cubic Fd3̅m spinel-type structure was obtained in the Co-rich, Mn−Co−O oxide nanocrystals, while a distorted tetragonal-type spinel phase with a space group of I41/amd, induced by the Jahn–Teller effect, formed in their Mn-rich counterparts. It is noted that the structural transformation involves the migration of Mn/Co cations from the octahedral interstices to the tetrahedral interstices, which is accompanied by the reduction of Mn/Co cations and oxygen evolution. A novel mechanism for the structural transformation and reaction scheme is proposed in this work.