AVS 61st International Symposium & Exhibition
    Atom Probe Tomography Focus Topic Friday Sessions
       Session AP+AS+NS+SS-FrM

Paper AP+AS+NS+SS-FrM4
Nanoscale Imaging of Li and B in Glass Samples, a Comparison of ToF-SIMS, NanoSIMS, and APT

Friday, November 14, 2014, 9:20 am, Room 301

Session: Correlative Surface and Interface Analysis with APT
Presenter: Zihua Zhu, Pacific Northwest National Laboratory
Authors: Z. Zhu, Pacific Northwest National Laboratory
Z.Y. Wang, Pacific Northwest National Laboratory
J. Liu, Pacific Northwest National Laboratory
J. Crum, Pacific Northwest National Laboratory
J.V. Ryan, Pacific Northwest National Laboratory
D.K. Schreiber, Pacific Northwest National Laboratory
J.J. Neeway, Pacific Northwest National Laboratory
Correspondent: Click to Email
A widely used method to immobilize nuclear wastes is fusing them into glasses. These proposed glass waste forms are multicomponent complex material with the common components of Li and B compounds. It is difficult for commonly-used surface analysis tools (e.g., X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy, scanning electron microscope/energy dispersive spectroscopy (SEM/EDX), and transmission electron microscope/energy dispersive spectroscopy (TEM/EDX)) to image the distributions of ultra-light elements like Li and B with sub-micron lateral resolutions. Time-of-flight secondary ion mass spectrometry (ToF-SIMS), NanoSIMS, and atom probe topography (APT) were used to image Li and B distributions in several representative glass samples. ToF-SIMS can provide ~100 nm lateral resolutions if using Li+ and BO2- images. However, both positive ion mode and negative ion mode are needed because neither B signals in positive ion mode nor Li signals in negative ion mode can provide adequate intensity to form qualified images. NanoSIMS can provide ~100 nm lateral resolutions if using Li- and BO2- images, while the lateral resolution of positive ion mode of NanoSIMS is poor (~400 nm). APT can provide ~2 nm lateral resolution for Li+ and B+ in a 3-D mode and quantification of APT is better than that of SIMS. While APT can provide much better ultimate lateral resolution than ToF-SIMS and NanoSIMS, it has three drawbacks: limited field-of-view, time-consuming sample preparation, and frequent/unpredicted sample damage during measurement. As a comparison, field-of-view of SIMS is flexible, sample preparation is simple, and little unpredicted sample damage occurs during SIMS measurement. Therefore, SIMS and APT can be regarded as complimentary techniques in nanoscale imaging of Li and B in glass samples.