Low thermal expansion Li2O-Al2O3-SiO2 (LAS) glass ceramic was examined as a host matrix for erbium ions. ZrO2 was added to the glass since it serves as a nucleating agent and as a good environment for the luminescent ions. The study was carried out on amorphous powders of the Li2O-Al2O3-SiO2/ZrO2/Er2O3 system prepared by the sol-gel method and successively crystallized at different temperatures. X-ray diffraction (XRD), transmission electron microscopy (TEM), and infrared (IR) spectroscopy were employed to study the evolution of the crystalline phases and the distribution of the erbium ions. The TEM micrographs confirmed that, after thermal treatment at 1000 degrees C, the crystallization of nanoparticles constituted by an Er2O3-ZrO2 solid solution with narrow size distribution could be achieved. On the contrary, erbium silicate was detected in the samples without ZrO2. The repartition constant of Er2O3 between ZrO2 and LAS matrix has been also evaluated.