A new structural type in alkaline rare-earth sulfides MRES.sub.2./sub. and TlRES.sub.2./sub.

0471447 - FZÚ 2017 US eng A - Abstract
Fábry, Jan - Havlák, Lubomír - Henriques, Margarida Isabel Sousa - Dušek, Michal - Rohlíček, Jan - Pasciak, Marek - Kopecký, Miloš - Kub, Jiří
A new structural type in alkaline rare-earth sulfides MRES₂ and TlRES₂.
Acta Crystallographica A-Foundation and Advances. Oxford Blackwell. s311-s311. ISSN 2053-2733. E-ISSN 2053-2733.
[29th European Crystallographic Meeting. 23.08.2015-28.08.2015, Rovinj]
R&D Projects: GA ČR(CZ) GA15-12653S; GA TA ČR TA04010135
Institutional support: RVO:68378271
Keywords : alkaline and thallium rare-earth sulfides * crystal chemistry * luminophores * structure analysis * diffuse scattering
Subject RIV: BM - Solid Matter Physics ; Magnetism

Some of the rhombohedral structures of the title compounds are promising class of luminofors. The present analysis was undertaken in order to improve crystal data which are necessary for crystal engineering. Single-crystal X-ray analysis of NaNdS2, NaSmS2 and NaEuS2 revealed a new structural type among Na rare-earth sulfides. This structural type has already been described for NaPrTe2. However, the symmetry of NaNdS2, NaSmS2 and NaEuS2 may be slightly distorted from the symmetry of Fdm as it is indicated by the Rietveld refinement. This structural type can be considered as a transitory state between the cubic phase which corresponds to NaCl with disordered cations and the rhombohedral one of alpha-NaFeO2 structural type. The structures of NaCl type show diffuse scattering which is most intense in NaLaS2. Moreover, another new structural type has been discovered for NaTbS2.

Permanent Link: http://hdl.handle.net/11104/0268836