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

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

Research output: Journal article publicationJournal articleAcademic researchpeer-review

8 Citations (Scopus)

Abstract

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 °C. The size of the cubic-zirconia crystal could be controlled by temperature and dwelling time. Both cubic-zirconia 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 ∼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.
Original languageEnglish
Pages (from-to)1079-1087
Number of pages9
JournalCrystal Growth and Design
Volume17
Issue number3
DOIs
Publication statusPublished - 1 Mar 2017

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics

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