On 20/11/2000, Armel wrote in answer to Daniela Kovacheva, who wrote:
> >Could somebody send me information about the structure of Ni2GeS4?
>
>This is typically a case for which you need several databases
>for solving it. Nothing about Ni2GeS4 in ICSD nor in CRYSTMET...
>The ICDD JCPDS database says (card 47-1583) that
>Ni2GeS4 belongs to the CrEr2S4 structure type...
This question was posted some weeks ago while I was away, and since Daniela
once worked at ILL I thought I would question whether Armel's answer, based
on non-Rietveld refined powder patterns in ICDD was the only possible
solution :-)
It is true that Ni2GeS4 is not in ICSD, but if if you look for structures
of type AB2X4 containing Ge,S4 you find a dozen entries. Knowing that Ni
belongs to the Fe-group of cations FEG you will find only orthorhombic
Fe2GeS4 (a structure done in Grenoble*) which seems as likely to be that of
Ni2GeS4 as does CrEr2S4.
My point is that you may need several databases, as Armel says, but you
should also be careful about assuming that they are infallible and that you
know the answer until you do a Rietveld refinement. But perhaps that has
been done by now Daniela ?
*Vincent,H. Bertaut,E. (1976) Acta Crystallogr.,Sect. 32 1749-1755
Alan Hewat, ILL Grenoble, FRANCE <[EMAIL PROTECTED]> fax direct (33) 4.76.20.76.48
tel (33) 4.76.20.72.13 (or .26 Mme Guillermet)
http://www.ill.fr/dif/AlanHewat.htm
