Combined Quantitative X-ray Diffraction, Scanning Electron Microscopy, and Transmission Electron Microscopy Investigations of Crystal Evolution in CaO-Al2O3-SiO2-TiO2-ZrO2-Nd2O3-Na2O System

文献类型： 外文期刊

第一作者： Liao, Chang-Zhong

作者： Liao, Chang-Zhong;Liao, Chang-Zhong;Shih, Kaimin;Liu, Chengshuai;Lee, Po-Heng;Stennett, Martin C.;Hyatt, Neil C.

作者机构：

期刊名称：CRYSTAL GROWTH & DESIGN （ 影响因子：4.076； 五年影响因子：3.924 ）

ISSN： 1528-7483

年卷期： 2017 年 17 卷 3 期

页码：

收录情况： SCI

摘要： Glass-ceramics, with a specific crystalline phase assembly, can combine the advantages of glass and ceramic and avoid their disadvantages. In this study, both cubic-zirconia and zirconolite-based glass-ceramics were obtained by the crystallization of SiO2-CaO-Al2O3-TiO2-ZrO2-Nd2O3-Na2O glass. Results show that all samples underwent a phase transformation from cubic-zirconia to zirconolite when crystallized at 900, 950, and 1000 degrees C. The size of the cubic-zirconia crystal could be controlled by temperature and dwelling time. Both cubiczirconia and zirconolite crystals/particles show dendrite shapes, but with different dendrite branching. The dendrite cubic-zirconia showed highly oriented growth. Scanning electron microscopy images show that the branches of the cubic-zirconia crystal had a snowflake-like appearance, while those in zirconolite were composed of many individual crystals. Rietveld quantitative analysis revealed that the maximum amount of zirconolite was similar to 19 wt %. A two-stage crystallization method was used to obtain different microstructures of zirconolite-based glass-ceramic. The amount of zirconolite remained approximately 19 wt %, but the individual crystals were smaller and more homogeneously dispersed in the dendrite structure than those obtained from one-stage crystallization. This process-control feature can result in different sizes and morphologies of cubic-zirconia and zirconolite crystals to facilitate the design of glass-ceramic waste forms for nuclear wastes.

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