Na Diffusion in Alkaline doped NASICON (Na3.1Zr1.95M0.05Si2PO12 (M = Mg, Ba))

NASICON, Na1+xZr2SixP3?xO12 (0 ? x ? 3), are known for good room-temperature Na-conductivities (~10?4 Scm?1), owing to the presence of a 3D cation transportation channel. Recently, alkaline doped NASICONs (Na3.1Zr1.95M0.05Si2PO12 (M = Mg, Ca, Sr, Ba)) were discovered and show promising Na- ionic conductivity at 300 K (~10?3 Scm?1). We propose to study the QENS and INS measurements of pure and alkaline doped NASICON to investigate the effect of doping on phonon spectrum and Na diffusion and their interplay. A larger alkaline element would be supposed to enhance the channel width for Na diffusion; however, it may also shift the phonon energies and locally distort the lattice, which could reduce the Na conductivity. The QENS and INS measurements will allow probing Na diffusion and the role of phonons in facilitating the Na hopping between available Na sites.