The NanoSIMS method is used here to contribute to the understanding of the separation and diffusion of elements in polycrystalline materials. The strategy is to use stable isotope marker 18O to create images and quantify oxygen integration.
A transparent YAG (yttrium aluminum garnet) sample was sintered and oxidized in an 18O2 environment at 1400°C. The 18O oxygen atoms diffuse into the ceramic through grain boundaries, demonstrated by two supplementary images (the grayscale image on the left), of 16O (the base element of the oxide) and 18O (integrated during the oxidation process). The full-color images show the separation of silicon dopant towards the grain boundaries in the YAG samples after sintering. In the top row (middle and right images), the same silicon image is shown on both linear and logarithmic scales, demonstrating the high sensitivity and dynamic range of the NanoSIMS dopant images. The image in the middle of the bottom row is a zoomed-in version of the image in the middle of the top row. The image in the bottom right shows another type of YAG sample indicating the dopant concentrated at the triple points.
Data provided by Dr. Hajime Haneda, NIMS, Tsukuba, Japan.