Subject: Re: CCL:Cell information on Fe2O3

From: Lorenzo Pueyo <[email-masked]>
Date: Mon, 19 Dec 1994 16:46:38 +0100

C. Qian ([email-masked]) asked:
>Does any one have the information about the cell size, positions of atoms,
>and space group information of Fe2O3 crystal?

Fe2O3 can be found in many different phases. At normal pressure and
temperature the thermodinamically most stable phase appears to be
$\alpha$-Fe3O3, Hematite, that is isostructural to $\alpha$-Al2O3 or
corundum. Crystallographic information for hematite follows:

Hexagonal   R -3 c (No. 167)  Z=6  a=5.0356(1) c=13.7489(7)
c/a=7.7303 (ideal hcp = 2.828)

Fe at (12c) : (0,0,z)
O  at (18e) : (x,0,1/4)

I could not find x and z values for Fe2O3, but they should be similar to
the parameters of corundum: z(Al)=0.352, and x(O)=0.306.

Further information on hematite could be found on the next reference:
Nat. Bur. Stand. (US) Monogr. 25 (1981) 18-37.

   Hope this helps you. Best regards,

                   Victor Lua~na

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