In this work, after the synthesis of chlorophosphate-
based host glasses doped with Yb ion as active ion,
their optical properties such as absorption and emission
spectra and thermal properties including transition and
crystallization temperature were investigated. By using the
DSC analysis indicating the temperatures 500 C as Tg and
800 C as Tc, the suitable annealing temperature was
determined at 650 C and then the annealing of the
obtained glasses was done to convert them to glass–
ceramics. During this heat treatment, NaCl and CaCl2
nanocrystals were grown in the glass matrix and active ions
are trapped into this medium. Also, the structural features
were analyzed using XRD and SEM and then the size of
nanocrystals was obtained from Scherrer’s formula and
was evaluated in average 37 nm for 1 %Yb:G–C and
54 nm for 0.5 %Yb:G–C samples. Finally, the absorption
and emission spectra of the samples were recorded and
analyzed, indicating that the conversion of glasses to glass–
ceramics by heat treatment resulted in enhancement of
emission intensity about 17 times; so, these glass–ceramics
are applicable in frequency converters, solid state lasers
and optical devices