Mapping energetics of atom probe evaporation events through first principles calculations

Peralta, Joaquín; Broderick, Scott; Rajan, Krishna

doi:10.1016/j.ultramic.2013.02.007

Cited by 29 publications

(31 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…29 While the calculations in that work were not as theoretically rigorous as the calculations of Forbes, [14][15][16][17][18][19] we demonstrated that these were qualitatively accurate based on the relationships experimentally measured using APT. Our contribution here extends our previous studies to describe the bonding character represented through the charge density distributions for specific chemical neighborhoods.…”

Section: Introductionmentioning

confidence: 76%

Impact of extreme electrical fields on charge density distributions in Al3Sc alloy

Loyola

Peralta

Broderick

et al. 2016

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

Self Cite

View full text Add to dashboard Cite

In this study, the authors investigated how extreme electrical fields affect charge distribution of metallic surfaces and bond character at the moment of evaporation. The surface structure and neighborhood chemistry were also studied as a function of various field evaporation pathways. Density functional theory (DFT) was used to model the surface bonding and charge distribution and then correlate the DFT results with experimental results by comparing the calculated evaporation fields with atom probe tomography measurements. The evaporation fields of different surface neighborhood chemistries in L12-Al3Sc were calculated, with the Sc atoms occupying the corners of a cubic unit cell and the Al atoms occupying the face centers. Al-Al surface atoms are found via DFT to be more likely to evaporate as dimers because of the Al-Al shared charge density. In contrast, Al-Sc evaporates as single ions due to the increased density localized around the Sc atom. This difference in evaporation behavior correlates with the resistance to degradation under extreme fields. This work allows better interpretation of the atom probe data by clarifying the relationship between different evaporation events and the role of surface and subsurface chemistry.

show abstract

Section: Introductionmentioning

confidence: 76%

Impact of extreme electrical fields on charge density distributions in Al3Sc alloy

Loyola

Peralta

Broderick

et al. 2016

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

Self Cite

View full text Add to dashboard Cite

show abstract

“…In our previous paper, we correlated the DFT calculations on field evaporation with the APT data by utilizing ion evaporation maps [1,29]. In the case of multi-hit events (that is, more than one ion detected at the same time), the ion evaporation map can be used to plot the pair-wise interactions.…”

Section: Correlating Charge Density With Apt Evaporationsmentioning

confidence: 99%

“…In our prior work [1], we used atomistic modeling to discriminate the evaporation field for single ion evaporations versus dimer evaporations in APT, thereby providing a more accurate input into the data reconstruction. This paper builds on that prior work by now defining the mechanism which leads to different relative bond strengths and different evaporation pathways under extreme electric field environments.…”

Section: Introductionmentioning

confidence: 99%

Impact of Extreme Electrical Fields on Charge Density Distributions in Alloys

et al. 2016

Self Cite

View full text Add to dashboard Cite

The purpose of this work is to identify the field evaporation mechanism associated with charge density distribution under extreme fields, linking atom probe tomography (APT) experiments with density functional theory (DFT) modeling. DFT is used to model a materials surface bonding, which affects the evaporation field of the surface atoms under high electric fields. We show how the evaporation field of atoms is related to the charge density by comparing the directionality and localization of the electrons with the evaporation of single ions versus dimers. This evaporation mechanism is important for the reconstruction of APT data, which is partially dependent on the input evaporation fields of the atoms. In L12-Al3Sc, Al-Al surface atoms are more likely to evaporate as dimers than Al-Sc surface atoms. We find that this is due to Al-Al having a shared charge density, while Al-Sc has an increased density localized around the Sc atom. Further, the role of subsurface layers on the evaporation physics of the surface atoms as a function of charge density is considered. Beyond the practical considerations of improving reconstruction of APT data, this work provides an approach for design of surface chemistry for extreme environments.

show abstract

“…A challenge which we address is the ion deviation from the ideal positions due to our limited understanding of ion trajectory near the tip immediately after evaporation. While the ion trajectory can be accurately modeled away from the tip based on geometrical factors, the trajectory and evaporation field are impacted by neighborhood chemical arrangement [1], laser heating, and electronic effects [2]. This represents a significant challenge which we have previously addressed through density functional theory (DFT) calculations, where the relationship between evaporation field, materials chemistry, and relative bonding were correlated (Figure 1).…”

mentioning

confidence: 99%

Coupling of First Principles and Machine Learning for High Throughput Calculation of Evaporation Fields

et al. 2018

Self Cite

View full text Add to dashboard Cite

The objective of this work is to understand the field evaporation process through a high throughput data driven approach. We link atomic probe tomography (APT) experiment, first principles computation, and informatics to (i) model the degradation mechanism under extreme fields, (ii) develop new modeling approach for field based on experimental calibration, and (iii) develop high throughput models for predicting evaporation field as function of chemistry, governing experimental design strategy. A challenge which we address is the ion deviation from the ideal positions due to our limited understanding of ion trajectory near the tip immediately after evaporation. While the ion trajectory can be accurately modeled away from the tip based on geometrical factors, the trajectory and evaporation field are impacted by neighborhood chemical arrangement [1], laser heating, and electronic effects [2]. This represents a significant challenge which we have previously addressed through density functional theory (DFT) calculations, where the relationship between evaporation field, materials chemistry, and relative bonding were correlated (Figure 1). This work develops the materials design triumvarate of experiment, computation and informatics. The experiment-computation link results in atomic scale measurement with electronic scale degradation mechanisms, the experiment-informatics link leads to high throughput prediction of APT parameters, and finally the computation-informatics link defines the relationship between chemistry and property. Our objective is to understand the mechanism associated with the change in evaporation fields (ie. required applied voltage) by performing DFT calculations to measure evaporation field as a function of chemistry and structure. We connect the field evaporation (Fe) with chemistry -ie. scaled descriptors associated with chemistry such as radii, electronegativity, charges, bonding, etc. From DFT / experiment, we determine the evaporation field for both single element systems and semi-conductors, with additional parameters associated with instrumental parameters when available (such as from the EPOS file). We use kernel principal component analysis to describe correlations by decomposing the data into a matrix which allows us to visualize data with non-linear physics incorporated into the model. The initial results from the informatics analysis provides a high throughput model between chemistry and evaporation field (Figure 2), which can be applied for improved reconstruction and material selection. The integration of the seperate experiment, computation and informatics thrusts contribute to a full design platform linking physical understanding with empirical measurement.

show abstract

Mapping energetics of atom probe evaporation events through first principles calculations

Cited by 29 publications

References 40 publications

Impact of extreme electrical fields on charge density distributions in Al3Sc alloy

Impact of extreme electrical fields on charge density distributions in Al3Sc alloy

Impact of Extreme Electrical Fields on Charge Density Distributions in Alloys

Coupling of First Principles and Machine Learning for High Throughput Calculation of Evaporation Fields

Contact Info

Product

Resources

About