Phase separation in rare-earth-doped SiO2 glasses

Abstract Phase separation in the rare-earth silicates, which is closely related to the phenomenon of concentration quenching in laser glasses, is discussed in terms of the theory of corresponding states in charged particle systems. This theory has been previously shown to apply to related systems such as the alkali and alkaline-earth silicates. Literature values of the critical temperatures and concentrations of the rare-earth silicates are found to increase with decreasing rare-earth ion radius in agreement with the corresponding states theory. Reduced values of the critical parameters are in excellent agreement with those of other charged particle systems if it is assumed that the rare-earth ions are effectively divalent. This assumption is consistent with the high degree of association observed for charged particle systems at their critical points. The theory of corresponding states is used to estimate the Er 2 O 3 SiO 2 immiscibility boundary by rescaling data from the Nd 2 O 3  SiO 2 system.