Re: LaB6 refinement

Fujio IZUMI ( izumi@nirim.go.jp )
Wed, 6 Sep 1995 08:44:08 +0900

>Hi all.
>
>I have been having some difficulty refining LaB6 for use as an
>instrumental calibration standard. I have only tried a "basic"
>refinement, including scale factor, profile shapes, asymmetry,
>pattern shift, and Boron multiplicity. I had read that it was closer to
>about 5.8 instead of 6. My problem lies in the first two peaks. My
>measured intensity is much lower than the calculated. I'm using Rietan94
>by Dr. Izumi.
>
>I'm fairly new to this and I am unsure of where to go from here. Any
>suggestions? Thanks-

Dear Dr. Meilicke:

In RIETAN-94, we need to input not an occupation number (i.e., number of
atoms in the unit cell) but an occupation factor (full occupancy = 1). Did
you input in such a way?

In addition, I point out that refinement of structure parameters for light
elements such as boron in compounds containing heavy metals (in this case,
La) is fairly difficult.

I do not know the 2-theta's for the first two peaks. If they are lower
than 20 degrees, their intensities may be lowered unless the width of the
divergence slit is decreased.

********************************************
Fujio IZUMI
National Institute for Research in Inorganic Materials
1-1 Namiki, Tsukuba, Ibaraki 305, Japan
TEL: 81-298-51-3351 (ext. 378)
FAX: 81-298-52-7449
E-mail: izumi@nirim.go.jp
********************************************