Nucleation and anionic environment of Er3+ in a germanate glass

The nucleation of PbF2 crystallites has been investigated in a germanate glass (GeO2–PbO–PbF2) doped with different erbium oxide and halides: Er2O3, ErF3, ErOF and ErCl3. Differential thermal analysis has been conducted on a unique glass composition doped with a variable content of these four erbium compounds. A memory of the initial coordination sphere, anionic neighbouring, of the erbium ions before melting of the powders has been observed in the as melted glasses through the variation of their thermal analysis curves and through their nucleation tendency obtained after thermal treatments.