cI80, bixbyite

Structural type	bixbyite
Common name	bixbyite, C-type rare-earth structure
Definition
Prototype	(MnFe)O3 and In2O3
Pearson symbol	cI80
Space group	206 Ia-3 T_h⁷
Chemical formula	A2X3
Bonding	ionic-covalent
Atomic positions	`A1 (8b) 1/4 1/4 1/4 (marked by C) A2 (24d) xi2 0 1/4 (marked by N) X (48e) xi eta zeta (marked by S)`
Coordination	see the fragment
PDB files	cI80 (with vacancies marked by O, fragment)
Parameters	xi2≤0, xi≥3/8, eta≥1/8, zeta≥3/8
Substances	sesquioxides of III metals including lanthanoids (see the table below)

This lattice can be considered as deformed C1 fluorite lattice (AX2)
. A1 (8b) 1/4 1/4 1/4 (marked by C) . A2 (24d) 0 0 1/4 (marked by N) . X1 (48e) 3/8 1/8 3/8 (marked by S) . X2 (16c) 1/8 1/8 1/8 (marked by O) xi3 xi3 xi3with vacancies at positions X2 (pdb).

A	X	a	xi2	xi	eta	zeta
Sc	O	9.846	.9649	.3928	.1528	.3802
Y	O	10.596	.9679	.3907	.1518	.3802
Ho	O	10.605	.9682	.3913	.1512	.3798
In	O	10.118	.969	.390	.153	.386
Tl	O	10.534	.9682	.3905	.1542	.3824