2006/04/11 by Chia-Jyi Liu, Tsung-Hsien Wu, Liu, Chia-Jyi +11
Physics and Astronomy · #FOS: Physical sciences #Superconductivity (cond-mat.supr-con) #cond-mat.supr-con
paper · pdf · doi:10.48550/arxiv.cond-mat/0604264
10 pages, 4 figures
arxiv created 2006/04/11 · arxiv updated 2009/12/01
By deintercalation of Na+ followed by inserting bilayers of water molecules into the host lattice, the layered cobalt oxide of gamma-Na0.7CoO2 undergoes a topotactic transformation to a layered cobalt oxyhydrate of Na0.35(H2O)1.3CoO2-delta with the c-axis expanded from c = 10.9 anstrom to c = 19.6 anstrom. In this paper, we demonstrate that the superconducting phase of c = 19.6 anstrom can be directly obtained by simply immersing gamma-Na0.7CoO2 powders in electrolyzed/oxidized (EO) water, which is readily available from a commercial electrolyzed water generator. We found that high oxidation-reduction potential of EO water drives the oxidation of the cobalt ions accompanying by the formation of the superconductive c = 19.6 anstrom phase. Our results demonstrate how EO water can be used to oxidize the cobalt ions and hence form superconducting cobalt oxyhydrates in a clean and simple way and may provide an economic and environment-friendly route to oxidize the transition metal of complex metal oxides