Effect of Al2O3 on phase separation of SiO2–Nd2O3 glasses

The immiscibility boundary and the critical point of SiO2–Nd2O3 system glass were determined as a function of Al2O3 addition. The critical temperature of the immiscibility boundary was observed to decrease with the addition of Al2O3. Using the regular solution model, the observed decrease of the immiscibility boundary was directly related to the decrease of the concentration fluctuation of Nd2O3 in SiO2. It is concluded that the Al2O3 addition to Nd2O3 containing silica glass is beneficial in decreasing the concentration quenching effect, deterioration of the optical efficiency due to clustering of rare earth element, because Al2O3 addition diminishes the concentration fluctuation of Nd2O3 in silica glass.