File:Rhomboedrique D51 2.svg

Cristal diatomique rhomboédrique (type α-Al₂O₃, α-Fe₂O₃). Groupe d'espace : ${\displaystyle \mathrm {R{\bar {3}}c} }$ (167), notation Strukturbericht : D5₁.

C'est un cristal A₂B₃. Les atomes de B forment un réseau hexagonal compact. Les atomes de A occupent les deux-tiers des sites interstitiels octaédriques. On a donc deux types de plans d'atomes B, notés A et B, et trois types de plans d'atomes A, notés a, b et c, formant une alternance

A-a-b-B-c-a-A-b-c-B-a-b-A-c-a-B-b-c-A-a…

Diatomic rhombohedral crystal (e.g. α-Al₂O₃, α-Fe₂O₃). Space group: ${\displaystyle \mathrm {R{\bar {3}}c} }$ (167), Strukturbericht notation: D5₁.

This is a A₂B₃ crystal. The B atoms make a hexagonal close-packed lattice. The A atoms occupy two-third of the octahedral interstitial sites. There are thus two types of B atoms planes, A and B planes, and three types of A atoms planes, a, b and c planes, which pile up as:

A-a-b-B-c-a-A-b-c-B-a-b-A-c-a-B-b-c-A-a…

Réalisé avec/created with : Inkscape

Voir aussi/see also

• Image:Rhomboedrique D51.svg
• Image:Corindon structure cristalline.svg

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