2. Hypothesis and Introduction
10/2/2016
•Disspute over existence of
type-III complexions
•APT solution
•3D mapping of GB
volume
•Sub-nanometer spatial
resolution
•Measure Gibbsian GB
solute excess
3. Defense of Hypothesis
10/2/2016
•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.
4. Critical Experiment
10/2/2016
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
5. Critical Experiment (cont.)
10/2/2016
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
6. Interpretation of Results
10/2/2016
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
