Chemical stability of ZrF 4- and AlF 3-based heavy metal fluoride glasses in water

Abstract

Glasses of the compositions 50ZrF 4–33BaF 2–10YF 3–7AlF 3 and 40AlF 3–12BaF 2–22CaF 2–16YF 3–10SrF 2 (mol%), respectively, were corroded in H 2O for different times at 20–80°C. The cationic species Zr, Al, Ba, Y, etc. were measured by secondary neutral mass spectrometry, whereas H was measured by nuclear reaction analysis. In the case of the ZrF 4-based glass the reaction depths follow at 20°C a dependence proportional to t, the attack time. This dependence changed with temperature as the t at 80°C. The H reaction profiles fit well into this scheme. In the case of the AlF 3-based glass also a t -dependence is obtained at 80°C. Whereas the reaction layer peels off for the ZrF 4-based glass for longer times (>1 h), it is relatively stable on the AlF 3-based glass and protects it against further attack. The AlF 3-based glass is about 10 times more stable in water than the ZrF 4-based glass.