Thermal, chemical and structural characteristics of the erbium-doped sodium phosphate glasses with 1-6 mol% Er2O3 were investigated. The glass transition temperature increase, but the thermal expansion coefficient and the dissolution rate of the glasses decrease with increasing Er2O3 content. X-ray photoelectron spectroscopy (XPS) and Fourier transformed infrared (FTIR) spectrometer were used to inspect the structural changes of the glasses. The doping of Er2O3 induces the depolymerization of the glasses at the Q(3) tetrahedral sites. The relative content of bridging oxygen (b-O) decreases and that of non-bridging oxygen (nb-O), which is attributed to the forming of the ionic P-O- (...) Er3+ linkages between phosphate chains, increases with increasing Er2O3 content. (C) 2003 Elsevier B.V. All rights reserved.