2. Physical properties of fluoride glasses

2.1 Thermal and mechanical properties

Like all glasses, fluoride glasses have three characteristic temperatures:

• glass transition temperature (T _g );

• the temperature at which crystallization begins (T _c or T _x );

• the melting start temperature of the crystallized species (T _f or T _m ).

The stability of a glass with respect to crystallization is primarily assessed by the temperature difference ΔT, introduced in paragraph...