Abstract: Phase transitions of Li₂O-Al₂O₃-SiO₂ based glass-ceramic materials, which can be used for the fabrication of optical fiber ferrule, were studied by
means of DTA, XRD, SEM and CTE. The temperature range of the phase transition studied was 850～1270℃. The results show that the metastable
β-quarts s.s first precipitates at 870℃ and translates into the β-spodumene s.s, the prominent crystal phase, at higher temperature. Increasing the heat-treatment temperatures from 900℃ to 1000℃ and prolonging
the time, the size of the granule changes little. With the transition of β-quarts s.s. to the　β-spodumene s.s, the CTE of the material increases greatly and
then it gradually stabilizes when the transition is completed. During the heat-treatment of the material at 1150～1270℃, the granule size grows and the glass
phase increases quickly. At the same time, the CTE of the material increases too.

Key words: glass-ceramics, crystal phase, microstructure, coefficient of thermal expansion