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Tetrahedral Co(II) coordination in alpha-type cobalt hydroxide: Rietveld refinement and X-ray absorption spectroscopy
Renzhi Ma1, Zhaoping Liu, Kazunori Takada
1Advanced Materials Laboratory, National Institute for Materials Science, Namiki 1-1, Tsukuba, Ibaraki 305-0044, Japan. MA.Renzhi@ nims.go.jp
Abstract:
We report a Rietveld refinement analysis and X-ray absorption study on a green-color Cl(-)-intercalated alpha-type cobalt hydroxide phase. The refinement clearly demonstrated that one-fifth to one-sixth of the Co(II) at octahedral sites was replaced by pairs of tetrahedrally coordinated Co(II) on each side of the hydroxide plane, represented by a structural formula of [Co(octa)(0.828)Co(tetra)(0.348)(OH)2](0.348+)Cl(0.348).0.456H2O. X-ray absorption spectroscopy also indicated that the divalent cobalt were in local neighboring environments of both octahedral and tetrahedral coordination. Furthermore, UV-vis spectroscopic measurements elucidate the typical green/blue color of an alpha-type cobalt hydroxide.
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