05/02/2023

Atomic Probe Tomography Proposed Experiment

George J. Ferko V

05/02/2023

Hypothesis and Introduction

•Disspute over existence of type-III complexions

•APT solution•3D mapping of GB volume•Sub-nanometer spatial resolution•Measure Gibbsian GB solute excess

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Defense of Hypothesis•Major issues with APT• Difficulty of sample prep•No direct observation of GB width

•Determining GB width• Calculated from Gibbsian

excess from the concentration profile

• Number of mono-layers is expected

to be ~2

Letellier, L, et al., Direct Observation of Boron Segregation at Grain-Boundaries in Astroloy by Atomic Tomography, Scripta Metallurgica et Materialia, 30, 1994, pp. 1503-1508, and Hudson, D and G. Smith, Initial Observation of Grain Boundary Solute Segregation in a Zirconium Alloy (ZIRLO) by Three-Dimensional Atom Probe, Scripta Materialia, 61, 2009, pp. 411-414.

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Critical Experiment

Dillon, SJ, and Harmer, MP, Multiple grain boundary transitions in ceramics: A case study of alumina, Acta Materialia, 55, 2007, pp. 5247-5254.

Miller, MK, et al., Review of Atom Probe FIB-Based Specimen Preparation Methods, Microscopy and Microanalysis, 13, 2007, pp. 428-436.

Thompson, K, et al., Three-dimensional Atom Mapping of Dopants in Si Nanostructures, Applied Physics Letters, 87, 2005, pp. 052108-1-3.

•FIB lift out

•Welding area of interest to microtip

•Annular milling

•Specimen requirements

• Tip radius ~50 to ~150 nm

• Side taper < 5°

•Low current/low accelerating voltage used in final steps

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Critical Experiment (cont.)

Miller, MK, et al., Review of Atom Probe FIB-Based Specimen Preparation Methods, Microscopy and Microanalysis, 13, 2007, pp. 428-436.

Moody, MP, et al., Qualification of the Tomographic Reconstruction in Atom Probe by Advanced Spatial Distribution Map Techniques, Ultramicroscopy, 109, 2009, pp. 816

Miller, MK and RG Forbes, Atom Probe Tomography, Materials Characterization, 60, 2009, pp. 462

Seidman, DN, and K Stiller, An Atom-Probe Tomography Primer, MRS Bulletin, 34, 2009, pp. 719.

Ga Implantation Problem

•Voltage and laser pulses for ceramics

•Ions projected through local electrode

•Crossed delay line detector

•Time-of-flight detector

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Interpretation of Results

Miller, MK and RG Forbes, Atom Probe Tomography, Materials Characterization, 60, 2009, pp. 465-466.

•Further insight into solute concentration profile

•Isoconcentration surfaces/volumes

•Calculation of Gibbsian excess will lead to the GB width

•3D reconstruction needs no interpretation if of good quality