STRUCTURAL AND PHYSICAL CHARACTERIZATION OF THE LI2OP2O5CRO1.5 ION-CONDUCTING GLASSES

Li2O:P2O5:CrO1.5 glasses containing 40, 50 and 60 mol% Li2O and a varying P2O5-to-CrO1.5 ratio have been synthesized, The glass-transition temperature and density increase as P2O5 is progressively replaced by CrO1.5. The glasses, being green in colour and showing strong optical absorption at 450 nm and 660 nm, contain predominantly Cr3+ ions and a relatively small amount of Cr6+ ions. The proportions of phosphate species with one, two, and three non-bridging oxygen atoms are determined from Raman spectroscopy results. From X-ray photoelectron spectroscopy (XPS) binding energies of the Li 1s, P 2p, Cr 2p and O 1s core levels are determined. The O 1s spectrum is found to consist of two peaks which are attributed to the P=O, P-O-P, P-O, P-O-Cr, and Cr-O oxygen species. Conductivity of these glasses increases with increasing Li2O content and with progressive replacement of P2O5 by CrO1.5. The 0.60Li2O:0.32P2O5:0.08 CrO1.5 glass is found to have the highest conductivity, 3.2 X 10(-6) OMEGA-1 cm-1 at 25-degrees-C. Compositional dependence of the conductivity is discussed in relation to variations in the glass structure.