The heat capacity, softening temperature, and crystallization temperature o
f RbF-BeF2 (10, 15, 18, 22, and 27 mol % RbF) glasses were measured by diff
erential scanning calorimetry. The results lend support to the view that Rb
F-BeF2 glasses are diphasic. The glasses studied are shown to contain fragm
ents of (BeF3)(n)(n-) flluoroberyllate chains and to be close in many aspec
ts to KF-BeF2 glasses.