Study on Chemical Durability of BAP System Glass Doped with Rare Earths

The chemical durability of BaO-Al₂O₃-P₂O₅(BAP) system glass doped 10% and 15% Sm₂O₃ was studied by SEM technique. The results indicated that addition of Al³⁺ and Sm³⁺ affected the water resistance ability obviously. The higher of Al³⁺ and Sm³⁺ content, the more stable of glass structure, so well as the better of water resistance ability of the Sm₂O₃ doping phosphate glass. Improvement of the polarize ability (Z²/r) of cations would improve acid resistance ability of rare earth phosphate glass, at the same time, overlays on the glass surface were formed by acid corrosion, which slowered the corrosion rate. In alkali medium, the corrosion mechanism was that the metal ions of phosphate long chains were hydrated, which disentangled the P-O-P bond and formed the orthophosphate units dissolved. And increase of Sm³⁺ ions resulted in decrease of the alkali resistance ability.