Bulk and thin film amorphous lithium aluminosilicate gels were prepared by sol-gel process. The structure of these materials was studied by solid state nuclear magnetic resonance (NMR) and X-ray photoelectron spectroscopy (XPS). ~7Li NMR studies on the bulk xerogels indicate two kinds of lithium ions: (a) polycrystalline LiCl dispersed in the pores of the gel and (b) lithium ions associated with AlO_4 units. The non-bridging oxygens were also observed in the thin film gel by XPS. The ac impedance spectrum of the thin film gel was fitted by a least-square method. The ionic conductivity of the thin film gel is comparable to that of the bulk xerogel. High-temperature humidity sensing property of the thin film gel was also evaluated.
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