Alan wrote :
>Yes of course. But as Uwe Kolitsch pointed out the structure to which Armel refers is
>in fact in ICSD, which should be the first place to look, since it contains many more
>entries than any of these other databases - 59,482 on the UK central server
>http://cds3.dl.ac.uk/dif/icsd/ which is available "free" to all UK academics. I found
>"khademite" there within seconds.
I was probably not clear enough in my dark story ;-)
First, you found it within seconds because I told you the
compound name. That would not have been that simple if I
had given you the raw powder pattern.
If you had an old ICSD version (1999), you would not have found
khademite, since that 1981 structure was added in the ICSD
database only in 1999.
Moreover, ICSD is not the first place to look in such a case. I know
that you do not practice a lot identification of compounds because most
powders coming at ILL are already identified. But identification
should be done by a search-match program working on the PDF-2
ICDD database. Fortunately, the ICDD database had some
entries about khademite and rostite, however, it could not
have the corresponding ICSD recent one (1999), because there is
some delay between the ICSD production and the incorporation
of new ICSD entries into ICDD PDF-2.
Maybe ICSD is the best database for structures of inorganic
compounds, but you may need PDF-2 from ICDD in order to
say what exactly is your sample to the ILL committee examining
the experiment proposal. And it is not excluded that using
further free mineralogical database could give you some more
data possibly lacking in ICSD and/or ICDD.
Infallibility supposes also completeness.
If 1981 data are added 18 years later in some databases, then
I am sure to be able to propose more dark stories soon ;-).
(Note that I could say about >200000 known organic and
organometallic structures still lacking in ICDD PDF-2, but
they are promised for a near future).
Best,
Armel Le Bail
http://sdpd.univ-lemans.fr/course/
