Preparation and Leaching Property of Nd-doped Zirconolite-based Glass-ceramic

Nd-doped zirconolite-based glass-ceramics were prepared by melting-heat treatment technique. The effects of heat treatment processing on phase structure of the glass-ceramics were investigated. The leaching properties of the glass-ceramics were also evaluated by static leaching experiments (product consistency test, PCT). The results show that glass transformation temperature (T_g) and crystallization temperature of the glass-ceramics are about 580 ℃ and 740 ℃, respectively. CaTiO₃ phase forms easily when the glass-ceramics were prepared by two-step method, i.e. the glass was prepared first, and then it was heat-treated at the crystallization temperatures. 2M-zirconolite phase can be obtained by one-step method, i.e. the heat-treatment immediately followed by the melting process. In addition, the zirconolite crystals exhibit a dendritic shape. The normalized mass loss of B and Na in the glass-ceramics remains almost unchanged (about 1 mg/m²) after 14 days, while the normalized mass loss of Nd reaches stable value (about 0.2 mg/m²) after 28 days. The normalized mass loss of B, Na, and Nd in the glass-ceramics is an order of magnitude lower than that of borosilicate glasses, respectively.