Effect of heat treatment on Li2O–B2O3–P2O5 glass soot fabricated by aerosol flame deposition

Li–B–P–O containing oxide nano-particles were synthesized from BCl3, POCl3 gases and an aqueous LiNO3 by flame hydrolysis reaction. Li2O–B2O3–P2O5 thin-film electrolyte was fabricated from as-deposited oxide particles by sintering at various temperatures between 500 and 600 °C. The effect of the sintering temperature on vitrification and electrical conductivity was investigated to find the optimum condition for the fabrication of thin-film electrolyte. Raman spectra and DTA measurement revealed that the crystalline H3BO3 impurity phase was included in the as-deposited film and was converted to glass former B2O3 during heat treatment above 550 °C. Raman spectra also indicate that the non-bridging oxygens within glass network increased with the vitrification at the elevated temperature. Accordingly, the conductivity of electrolyte was increased with increasing sintering temperature. However, in the ambient atmosphere, the diborate groups with non-bridging in glass electrolyte slowly transformed to H3BO3 again by reaction with moisture.