Nanoscale microstructure and chemistry of transparent gahnite glass-ceramics revealed by atom probe tomography.

The nanoscale microstructure and chemistry of a transparent gahnite glass-ceramic and its precursor glass were investigated using atom probe tomography, transmission electron microscopy, and nuclear magnetic resonance spectroscopy. In the annealed precursor glass, statistically significant ZrO clustering was observed along with Si depletion within 2 nm of the ZrO clusters. This clustering is expected to be the first step in the nucleation and crystallization of the nucleating agent, ZrO 2. In the glass-ceramic, gahnite (ZnAl 2 O 4) crystallites were found to exist in proximal locations to ZrO 2 and not in a core-shell arrangement. The residual glass composition was directly measured by atom probe, showing higher concentrations of Al, Zn, and Zr than previously expected. At the interfaces between the crystallites and residual glass, no enrichment or depletion zones were found. These findings provide answers to outstanding questions surrounding the nucleation and elemental partitioning, microstructure, and the residual glass composition of transparent gahnite glass-ceramics. [Display omitted] [ABSTRACT FROM AUTHOR]