Preparation and characterization of low-melting LiF–SnO–P<sub>2</sub>O<sub>5</sub> glasses

SnO-P 2 O 5 glasses are known to have a low glass transition temperature (T g ) and can be vitrified in combination with metal oxides and halides.In this study, the glass-forming region in the LiF-SnO-P 2 O 5 system was determined and the properties of the obtained glasses were characterized.The starting materials were melted at 400 C, and the glassforming regions in the LiF-SnO-P 2 O 5 system were determined using X-ray diffraction and thermal analysis.The glass-forming region was restricted to P 2 O 5 contents of at least 36 mol%, which is close to pyrophosphate, in LiF-rich compositions ( 30 mol%).On the other hand, the region extended to near the orthophosphate composition with high SnO content, such as 10LiF62SnO28P 2 O 5 (mol%).The glass transition temperature of the prepared glasses ranged from around 150 to 210 C.Sn K-edge X-ray absorption fine structure spectra of 10LiF62SnO28P 2 O 5 (mol%) glass showed that the valence of Sn is predominantly Sn(II).The X-ray photoelectron spectra confirm the formation of P-F bonds in the glasses.A chemical durability test in the ambient atmosphere revealed that the glasses in the LiF-SnO-P 2 O 5 system have relatively high chemical durability.AC impedance measurement showed the glass has ionic conductivity in the order of 10 -8 S cm -1 at room temperature.