2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/218441Data of 23Na NMR spectra- and relaxation measurements are interpreted as suggesting that, upon increasing temperature the Na layers in Na0.8CoO2 adopt a 2D liquid state at T=291 K. The corresponding first order phase transition is preceded by a rapidly increasing mobility and diffusion of Na ions above 200K. Above 291 K the 23Na NMR response is similar to that previously observed in superionic conductors with planar Na layers.4 pages, 4 figuresStrongly Correlated Electronstext