Comprehensive structural evaluation of the quaternary chalcogenide Ag₂CdSnSe₄

In this work, the synthesis of phase-pure Ag 2 CdSnSe 4 by a mechanochemical approach and a subsequent annealing step in an evacuated ampoule is presented. A detailed analysis of the X-ray diffraction pattern of the product revealed the presence of weak reflections, that cannot be observed in the previously proposed crystal structure with space group Cmc 2 1 . Our structural investigation led to the assumption that Ag 2 CdSnSe 4 crystallizes in the wurtzstannite-type structure with space group Pmn 2 1 (a structure type derived from Cmc 2 1 ). The aim of this contribution is to discuss the crystal structure of Ag 2 CdSnSe 4 using Rietveld refinements in space group Cmc 2 1 and its possible subgroups.