Effect of HfO2 addition on nucleation in ZnO-Al2O3-SiO2 glass

The effect of HfO2 addition on the crystallization behavior of ZnO-Al2O3-SiO2 glasses, which shows volume crystallization, was studied. The crystallization peak temperature (TC) obtained by DTA for as cast glasses decreased with the addition of HfO2. The crystallization peak temperature also decreased by nucleation heat treatments (NHT), and the difference of TC among samples depending on HfO2 content became less with the increase of NHT time. It was found that HfO2 works as a nucleation agent because the addition of HfO2 suppressed the precipitation of SiO2 by promoting the precipitation of Gahnite(ZnAl2O4). The effect of HfO2 on nucleation is less than TiO2 or ZrO2 which are known well as nucleation agents. The low diffusion rate of Hf due to its heavier atomic weight than Ti and Zr would be a reason for the low nucleation ability of HfO2. © 2015 The Society of Materials Science.