# F-center

> English word · Noun

## Definitions
1. A type of point defect in crystals where an anion (negative ion) vacancy in the lattice traps one or more electrons, creating a localized site that absorbs specific wavelengths of light, thereby coloring the typically transparent material (e.g. the yellowing of NaCl due to trapped electrons in missing chloride sites); defects that form due to irradiation (e.g. X-rays), heat, or alkali metal vapor treatment and can be removed by annealing.

## Etymology
F (from German Farbe, from Farbzentrum) + center.

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/word/f-center