percentueleatomaire

Percentueleatomaire is a proposed metric in materials science and physics for quantifying the fraction of atoms within a material that meet a defined criterion at the atomic scale. The term appears in discussions of atomic-scale characterization and serves as a conceptual analogue to chemical composition expressed as a percent.

Definition

For a region of interest containing N_total atoms, and a subset N_state of atoms that satisfy a chosen condition (for example, a specific oxidation state, coordination environment, spin state, or bonding motif), percentueleatomaire P is defined as P = (N_state / N_total) × 100%.

Measurement and computation

State assignment can derive from spectroscopy (X-ray absorption spectroscopy, electron energy loss spectroscopy), electron microscopy, atom probe tomography, or first-principles simulations. In practice, P depends on how the state is defined and on the spatial scope of the region.

Applications

Used to describe distributions of electronic or chemical states in catalysts, battery materials, corrosion layers, and nanoscale composites. It provides a compact summary of heterogeneity and can be compared across samples or experimental conditions when definitions are aligned.

Limitations and relationship to other concepts

Percentueleatomaire is not an established metric with a universally accepted standard. It overlaps with existing ideas such as atomic fraction or oxidation-state distribution, but differs in its emphasis on a chosen state criterion. Its value is sensitive to region selection, measurement uncertainty, and the method used to assign states.

See also

Atomic fraction, atomic percent, oxidation state distribution, atom probe tomography, X-ray absorption spectroscopy.

Notes

Because the term is not widely standardized, readers should consult the explicit definition used in any given source.