>
> I have always found more useful having LaB6 or corundum
Fabrizio's question "why use silicon powder" might have been answered more
precisely, and in much less than 64 ko (~64,000 letters :-) as follows:
The line width of the NIST Si powder sample 640e is no better than the NIST
sintered corundum disk 1976b, which is also slightly cheaper at $680. The
best NIST x-ray standard is however LaB6 powder 660c, which is 50% more
expensive; the line widths of the other two are 50% greater.
The recipe for making a silicon disk from powder is interesting, but why
bother if you can buy the sintered Al2O3 disk, if indeed you want a disk
rather than powder.
Alan
______________________________________________
* Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE *
<alan.he...@neutronoptics.com> +33.476.98.41.68
http://www.NeutronOptics.com/hewat
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