Superconductivity in three-layer Na0.3CoO2·1.3H2O

Raman spectroscopy study ofα-,β-,γ−NaxCoYang1, Xia2, Shi3 et al. 2006Phys. Rev. B30160View full textAdd to dashboardCite

“…These phases differ crystallographically in the stacking patterns of CoO 6 octahedra along the c-axis direction. [15][16][17][18][19][20][21] In the ␣-Na x CoO 2 system, the parent phase with a nominal composition of ␣-NaCoO 2 has a hexagonal cell with lattice parameters of a = 2.89 Å, c = 15.59 Å ͑R -3m space group͒; 20 the parent sample ␤-Na 0.6 CoO 2 has a monoclinic structure with a C2/m space group and lattice parameters a = 4.90 Å, b = 2.83 Å, c = 5.71 Å, and ␤ = 106.180°. 21 The parent material of ␥-Na 0.75 CoO 2 has a hexagonal cell with lattice parameters a = 2.84 Å and c = 10.80 Å ͑P6 3 / mmc space group͒.…”

“…The distance between two CoO 2 layers is almost the same for all three phases, each phase having its specific structural properties depending on Na concentration. [15][16][17][18][19][20][21] It is also noted that structural alternations in Na x CoO 2 can also be caused by the post-chemical treatments as commonly adopted for preparing the Na x CoO 2 sample with lower Na concentrations. For instance, our recent experimental results revealed that ␣-Na x CoO 2 materials undergo a clear phase transition from the hexagonal to the ␤-phase-like monoclinic structure along with the Na deintercalation.…”

Superconductivity of cobalt oxide hydrate, Na (H3O) CoO2· yH2O

“…Another type of BLH is synthesized from a-, b-Na x CoO 2 , in which the stacking pattern of the CoO 2 layer is different [18][19][20][21][22]. This exhibits superconductivity at approximately 4.6 K. Li x CoO 2 Á yH 2 O and K x CoO 2 Á yH 2 O, which may also include H 3 O ions, were reported soon after the discovery of the superconductor with Na [23][24][25] and do not exhibit superconductivity.…”

Magnetic and superconducting nature ofNa0.35CoO2⋅yH2OandSugiyama1, Ikedo2, Må̊nsson3 et al. 2010Phys. Rev. B

“…The volume fraction of the oscillatory signal was estimated as 22-27 % and the rest of muons were found to "see" a small and random nuclear magnetic field. According to numerical analyses of the ZF spectra, the origin of the oscillation was clarified as the formation of "͓H 3 …”

“…[2][3][4] Shortly after the discovery, the presence of oxonium ions ͓͑H 3 O͔ + ͒ in Na x CoO 2 · yH 2 O was proposed from chemical titration analyses. 5 That is, the Co valence ͑V Co ͒ was estimated as ϳ3.…”