Re: atomic position

[xtal]

At 17:21 14/06/2016 +0200, you wrote:

So far as I know (I may be wrong :-) ordered atomic positions for the two requested compounds, with supposed formulae Ba2TeO4 and Ba2TeO5, have not been determined. The closest I found were as I wrote: "<https://www.researchgate.net/publication/244748863_Sr3TeO6_and_Ba3TeO6_Double_perovskites_with_pronounced_superstructures>Sr Te O6 and Ba Te O6" and "<http://scripts.iucr.org/cgi-bin/getarticleid?issn=0108-2701&volume=41&fpage=1558&details=yes>Sr Te O4". I understand that unit cells and space groups have been assigned, but that is not sufficient.

If I am wrong, and ordered structures with this stoichiometry have indeed been determined, I hope people who have access to the databases will confirm that these structures actually exist, to save Rachid time and money. Otherwise it is not permitted to share or promote commercial databases on the Rietveld list.

Alan.

Hi Alan,

If I understand well, sharing or promoting open databases is permitted on
the Rietveld list...

About Ba2TeO5, it is said that it is isomorphous with Ba2WO5 and Sr2WO5.
Ba2WO5 belongs to the K2VO2F3 structure type which is described in an
Acta Cryst B issue and available as an entry in the Crystallography Open
Database :
http://www.crystallography.net/cod/2020524.html

It is orthorhombic pseudo-tetragonal with 2b~c
Ba2TeO5 was originally indexed as tetragonal or possibly orthorhombic.

So, here are very probably starting atomic positions for Ba2TeO5 ;-)

Best,
Armel

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