Implementation of focused ion beam (FIB) system in characterization of nuclear fuels and materials

Impact of carbon and platinum protective layers on EDS accuracy in FIB cross-sectional analysis of W/Hf/W thin-film multilayers

Achieving high-quality cross sections is essential for accurate analysis of multilayer coatings. One method of performing such cross sections is focused ion beam, where sample protection from ion damage in the form of protective layers applied by FEBID and FIBID methods is used. Due to the lack of comparative summaries of different layers applied by these methods, especially in the context of cross-sectional analysis and elemental analysis of the cross-section, it was decided to address the effect of the protective layer on the reliability of EDS analysis. This study compares the effectiveness of platinum and carbon protective layers in creating cross sections for W/Hf/W samples. The effect of protective layers on elemental mapping and elemental analysis accuracy was evaluated. This study highlights the importance of protective layer selection in providing reliable EDS analysis of cross sections.

Extraction of plutonium-containing microcrystals from Hanford soil using a focused ion beam for single-crystal X-ray diffraction analysis

Herein, the successful use of a focused ion beam/scanning electron microscope to prepare microsamples of radioactive single crystals for X-ray diffraction analysis is reported. This technique was used to extract and analyze crystalline Pu-containing particles as small as 28 µm3 from Hanford soil taken from the 216-Z-9 waste crib, which were then crystallographically characterized using single-crystal X-ray diffraction to confirm the cubic structure of PuO2. As a systematic proof of concept, the technique was first tested using UO2 crystals milled into cubic shapes with approximate volumes of 4620, 1331, 125, 8 and 1 µm3, in order to empirically determine the crystal size limits for characterization by a laboratory-based diffractometer with a sealed tube Mo or Ag anode X-ray source and a charge-coupled device detector.

Best practices for preparing radioactive specimens for EBSD analysis

A wide variety of specimen preparation techniques are available for ensuring that specimen surface finish has the acceptable quality for electron backscatter diffraction (EBSD) analysis. These techniques include but are not limited to vibratory polishing, broad, and focused ion beam milling. They have been widely implemented in the field of nuclear materials science with a varying degree of success. However, a systematic investigation of the effectiveness of each technique for preparation of highly radioactive specimens has not been conducted to date but would be beneficial during selection of the specimen preparation methodology. Multiple preparation techniques have been evaluated in this contribution with the final goal of determining the most effective technique for preparing radioactive specimens for EBSD analysis. This paper discusses the advantages and disadvantages of each technique and recommends best practices for preparing radioactive specimens for surface-based analysis techniques.

Ceramic nanowelding

Ceramics possess high temperature resistance, extreme hardness, high chemical inertness and a lower density compared to metals, but there is currently no technology that can produce satisfactory joints in ceramic parts and preserve the excellent properties of the material. The lack of suitable joining techniques for ceramics is thus a major road block for their wider applications. Herein we report a technology to weld ceramic nanowires, with the mechanical strength of the weld stronger than that of the pristine nanowires. Using an advanced aberration-corrected environmental transmission electron microscope (ETEM) under a CO₂ environment, we achieved ceramic nanowelding through the chemical reaction MgO + CO₂ → MgCO₃ by using porous MgO as the solder. We conducted not only nanowelding on MgO, CuO, and V₂O₅ nanowires and successfully tested them in tension, but also macroscopic welding on a ceramic material such as SiO₂, indicating the application potential of this technology in bottom-up ceramic tools and devices.