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NCUEIR > College of Science > Department of Physics > Periodical Articles > Item 987654321/14241

Please use this identifier to cite or link to this item: http://ir.ncue.edu.tw/ir/handle/987654321/14241

Title:	Water Intercalation of Sodium Cobalt Oxides Using Aqueous Permanganate Solution
Authors:	Liu, Chia-Jyi;Liao, Chia-Yuan;Hung, Wen-Ching;Wang, Jung-Sheng;Sheu, Hwo-Shuenn
Contributors:	物理學系
Keywords:	A. Superconductors;A. Oxides;B. Chemical synthesis;C. X-ray diffraction;C. XAFS (EXAFS and XANES);D. Transport properties
Date:	2008-05
Issue Date:	2012-09-10T06:15:28Z
Publisher:	Elsevier
Abstract:	We report direct synthesis of the potassium sodium cobalt oxyhydrates (Na,K)x(H2O)yCoO2−δ using the aqueous KMnO4 solution. Two distinct novel phases of (Na,K)x(H2O)yCoO2−δ are synthesized depending on the molar ratio of KMnO4/Na used to treat γ-Na0.7CoO2. Low molar ratio of KMnO4/Na leads to a superconductive phase with c≈19.6 Å, whereas high molar ratio of KMnO4/Na leads to a non-superconductive phase with c≈13.9 Å. According to the chemical analyses, it is found that a partial or even almost complete replacement of K+ for Na+ in the alkaline layers. When using aqueous KMnO4 solution with low molar ratio of KMnO4/Na, the water intercalation is very slow. We also present the XANES spectra on (Na,K)x(H2O)yCoO2−δ. The oxidation state of the Co for the 0.3X sample (c≈19.6 Å) is higher than that of the 40X sample (c≈13.9 Å) with a chemical shift of 3.5 eV.
Relation:	Journal of Physics and Chemistry of Solids, 69(5-6): 1483-1485
Appears in Collections:	[Department of Physics] Periodical Articles

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