Fast Ionic Conducting Glasses in the System 20LiCl-40Li(2)O-(80-x)PO5/2-xMoO(3): The Structural Dependence of Ion Conductivity Studied by Solid-State Nuclear Magnetic Resonance Spectroscopy

摘要

Glass samples with the stoichiometric components of 20LiCl-40Li(2)O-(80-x)PO5/2-xMoO(3) ( x = 0, 10, 20, 30, 40, 50, 60, and 70) are synthesized. The dependence of ion conductivity on structure is investigated. The structures of these glasses are investigated by Raman and solid-state nuclear magnetic resonance (NMR) spectroscopy. The phosphorus structure unit Q(nMo)((n)) species (where n represents the number of P-O-P linkages in per phosphorus species, while m denotes the number of P-O-Mo linkages) are identified by P-31 2D J-resolved and magic angle spinning NMR spectra. With the increase of MoO3, the phosphorus chains are broken into dimer phosphorus Q(0Mo)((1)) and orthophosphate Q(1Mo)((0)) species successively. Raman shows that both 4- and 6-coordination molybdenum exists in the glasses. In the glasses with x > 20, 6-coordination molybdenum becomes dominated. With the replacement of P by Mo, a large number of Li+ ions transfer from the phosphorus phases into molybdenum phases, resulting in an enhancement of the ionic conductivity. When the substituted amount (x) is 70, the ionic conductivity can be increased by about 250 times, i.e., reaches 1.05 x 10(-5) S.cm(-1).