2004/07/16 by Chia‐Jyi Liu, Chia-Jyi Liu, C. -Y. Liao +10
Chemistry · Materials Science · Physics and Astronomy · #Catalytic Processes in Materials Science #FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Pigment Synthesis and Properties #Superconductivity (cond-mat.supr-con) #Thermal and Kinetic Analysis #cond-mat.mtrl-sci #cond-mat.supr-con
paper · pdf · doi:10.48550/arxiv.cond-mat/0407420
7 pages, 10 figures
openalex publication_date 2004/07/16 · arxiv created 2007/05/11 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We have first used the aquesous KMnO4 solutions to de-intercalate and oxideze gamma-phase of Na0.7CoO2 and successfully form the superconductive phase of cobalt oxyhydrate hydrates (Na,K)xCoO2.yH2O with Tc=3.2-4.6K based on the magnetization measurements. The higher molar ratio of KMnO4/Na used to treat Na0.7CoO2 results in more removal of Na+ and leads to a partial or even complete replacement of K+ for Na+. The low molar ratio of KMnO4/Na forms a superconductive phase with the c-axis ca. 19.6 angstrom, whereas the high molar ratio of KMnO4/Na forms a non-superconductive phase with teh c-axis ca. 13.9 angstrom. The superconductive 19.6 angstrom phase is unstable with respect to the ambient air in terms of losing water molecule from the structure; nevertheless, the dehydration/hydration process is reversible when storing the sample in a chamber with sufficient humidity.