title: Preparation of Superconducting Na(x)(H2O)yCoO2 using NaMnO4 as the deintercalation and oxidation agent.
abstract: We have used aqueous NaMnO4 solution as the deintercalation and oxidation agent to treat gamma-Na0.7CoO2 powders and to successfully obtain superconducting sodium cobalt oxyhydrates, Nax(H2O)yCoO2, with onset Tc approximately 4.6 K without using highly toxic Br2/CH3CN solution. Chemical analyses indicate that the sodium content x decreases with increasing concentration of NaMnO4 solution and depends slightly on the immersion time. Unlike using a high concentration of aqueous KMnO4 as the deintercalation and oxidation agent, all the hydrated products are the c approximately 19.6 A phase with bilayers of water molecules intercalated between the CoO2 layers and sodium layers because of the absence of K+ in the Na+ layers.
authors.affiliation: Department of Physics, National Changhua University of Education, Changhua, Taiwan, ROC. liucj@cc.ncue.edu.tw
authors.forename: Chia-Jyi
authors.initials: CJ
authors.lastname: Liu
authors.forename: Wen-Chin
authors.initials: WC
authors.lastname: Hung
authors.forename: Jung-Sheng
authors.initials: JS
authors.lastname: Wang
authors.forename: Chia-Jung Charlie
authors.initials: CJ
authors.lastname: Liu