Fremdinterstitialatome

Fremdinterstitialatome is a term used in materials science and crystallography to describe atoms that occupy interstitial sites in a crystal lattice but are not part of the host lattice. Interstitial sites are the gaps between the regular lattice atoms, typically tetrahedral or octahedral spaces in close-packed structures. Fremdinterstitialatome differ from substitutional impurities, which replace host atoms, and from self-interstitials, which are host atoms occupying interstitial sites.

Their presence is governed by atomic size, chemical affinity, and processing conditions. Because interstitial atoms are often smaller than host atoms, they can diffuse rapidly through the lattice, especially at elevated temperatures. The incorporation of foreign interstitial atoms usually distorts the lattice and can alter electronic, thermal, and mechanical properties.

In metallic systems, common Fremdinterstitialatome include carbon, nitrogen, oxygen, and hydrogen. Carbon in iron forms steel with increased hardness and strength via interstitial solid-solution strengthening and, at certain compositions, microstructural transformations. Nitrogen and oxygen also modify strength and hardness and can affect ductility and creep; hydrogen can cause embrittlement or phase changes under certain conditions. In semiconductors, interstitial impurities can influence electrical conductivity and diffusion behavior.

Detection and analysis rely on techniques such as X-ray diffraction to detect lattice parameter changes, electron microscopy to observe defects and precipitates, and atom probe tomography or secondary ion mass spectrometry to map impurity distributions at near-atomic resolution.