Summary of Previous Results

Atom probe experimentation-Atomic scale measurement of gas-solid reactions of Al and Oxygen

- Compound formation- Study of Interfacial chemistry

-3D interface analysis of gas solid reactions - Iso surface concentrations -Interfacial chemistry, morphology, etc.

-Atomic scale measurement of gas-solid reactions of Si and oxygen

-Refinements in Environmental chamber set up for in-situ gas reactions

-Collaborations:- Maryland – Sample prepared by Maryland by reacting Si microtips;

analysis of samples by ISU- Van Duin group – Use of atom probe results for experimental

inputs into ReaxFF simulations

Atom Probe Data for ReaxFF

- Original AP data

-Data required for ReaxFF

-Modifications

Future Steps-Gas solid reactions of near space environment condition

-Surface reactions / orientation dependence of reactions

Chemistry of Gas-Solid Reactions

We have analyzed gas-solid reactions of materials and the resulting bonds

• Oxidation of Aluminum at 450 C, 2.5 x 10-3 Torr for 10 min.

The Al-O compounds shown are from an Al2O3 phase. By measuring the compounds, we get a more local chemical measurement – Al2O3 phase comprised of Al2O, Al2O2, AlO and AlO2 clusters.

Interface from Gas-Solid Reactions

Measurement of two dimensional interfaces.

Bulk Al2O3 phase Bulk Al phase

Interface shown from reaction of O and Al. Identify Al2O3 as bulk phase of gas-solid reaction, and perovskite phase at the interface.

We have further developed this approach to imaging of 3D interfaces.- Interface shape- Interface uniformity

Interface

Image of changing interfacial isosurfaces with changing interfacial chemistry.

Interface is uniform, and the shape of interface does not change significantly with chemistry.

Iso surface-Al (41%) Iso surface-Al (80%)

Al (97%)O (1.93%)

mass = 70 and charge=3 resulting in m/n peak in range of 23.2 - 23.5. 

Range10=23.2730 23.5960 Vol:0.06204 Al:2 O:1 Color:00FF00  

Number=11Ion1=AlIon2=OIon3=H……[Ranges]Number=23Range1=13.3740 13.8830 Vol:0.01661 Al:1 Color:33FFFFRange2=8.9770 9.2620 Vol:0.01661 Al:1 Color:33FFFFRange3=26.8780 27.4970 Vol:0.01661 Al:1 Color:33FFFFRange4=15.8811 16.4270 Vol:0.02883 O:1 Color:6666FFRange5=7.9460 8.1220 Vol:0.02883 O:1 Color:6666FFRange6=1.0000 1.0830 Vol:0.00000 H:1 Color:CCCC00Range7=2.0020 2.0400 Vol:0.00000 H:2 Color:FF0000Range8=21.3820 21.9550 Vol:0.04543 Al:1 O:1 Color:FF3333Range9=42.8450 43.5160 Vol:0.04543 Al:1 O:1 Color:FF3333Range10=23.2730 23.5960 Vol:0.06204 Al:2 O:1 Color:00FF00-------------

POS file

Range File

-2.21E+00 -1.19E+00 2.94E-01 286.47

-2.67E+00 -1.72E+00 3.98E-01 23.39 al2o

-4.28E-01 5.47E-02 1.30E-01 30.85

5.19E-02 3.82E-01 1.29E-01 45.73

1.17E+00 -2.63E+00 3.50E-01 48.43

-2.56E-01 -1.86E+00 2.21E-01 46.80

2.39E+00 -2.06E+00 3.94E-01 16.00 o

Atom Probe Data

X Y Z m/n

-2.60E-01 2.62E-01 2.80E-02 34.99 al2o

-1.52E+00 -8.78E-01 2.21E-01 13.67 al

1.32E-02 3.41E-01 3.61E-02 21.49 alo

X Y Z m/n

AP Data

1. All the compounds were identified and selected from the POS file

2. Compound ions converted into respective constituent ions at a given position

-2.60E-01 2.62E-01 2.80E-02

-2.60E-01 2.62E-01 2.80E-02

-1.52E+00 -8.78E-01 2.21E-01

1.32E-02 3.41E-01 3.61E-02

ReaxFF Data

X Y Z Atom type

-2.60E-01 2.62E-01 2.80E-02

1.32E-02 3.41E-01 3.61E-02

8.25E-01 1.06E+00 1.49E-01

8.25E-01 1.06E+00 1.49E-01

8.25E-01 1.06E+00 1.49E-01 32.15 o2

Al O

Al 4.00948 4.81846 36.33220 1Al 0.27611 4.06606 32.27097 1Al 6.66427 45.77823 34.90955 1