Crystallization of nanostructured ZrO₂ phase in borosilicate glass: Impact of Al₂O₃ on tetragonal-to-monoclinic phase transformation

Recently, we have developed the borosilicate glass, in which ZrO₂ phase is singly crystallizable, and has found an emissive monoclinic ZrO₂ dendrites in the resulting GCs. In order to promote the formation of monoclinic phase, we have examined the effect of substitution of alumina Al₂O₃ for ZrO₂ in the precursor glass composition, i.e., 15Na₂O–(15 − x)ZrO₂–xAl₂O₃–30B₂O₃–40SiO₂. It was found that the substitution of small amount of Al₂O₃ (x = 1) gave a positive effect, i.e., increase in the amount of monoclinic phase and decrease in the crystal size. Furthermore, the substitution improved the internal quantum-yield. On the other hand, the further substitution (x ≥ 2) provided the decrease in amount of the monoclinic phase.