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Cation distribution in Cu 2 ZnSnSe 4 , Cu 2 FeSnS 4 and Cu 2 ZnSiSe 4 by multiple‐edge anomalous diffraction
Author(s) -
Többens Daniel M.,
Gurieva Galina,
Niedenzu Sara,
Schuck Götz,
Zizak Ivo,
Schorr Susan
Publication year - 2020
Publication title -
acta crystallographica section b
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.604
H-Index - 33
ISSN - 2052-5206
DOI - 10.1107/s2052520620013384
Subject(s) - x ray absorption fine structure , crystallography , anomalous scattering , diffraction , absorption edge , synchrotron radiation , scattering , neutron diffraction , x ray crystallography , materials science , absorption (acoustics) , kesterite , chemistry , condensed matter physics , optics , crystal structure , physics , band gap , nanotechnology , thin film , quantum mechanics , spectroscopy , czts , composite material
Multiple‐Edge Anomalous Diffraction (MEAD) has been applied to various quaternary sulfosalts belonging to the adamantine compound family in order to validate the distribution of copper, zinc and iron cations in the structure. Semiconductors from this group of materials are promising candidates for photovoltaic applications. Their properties strongly depend on point defects, in particular related to cation order–disorder. However, Cu + , Zn 2+ and Fe 2+ have very similar scattering factors and are all but indistinguishable in usual X‐ray diffraction experiments. Anomalous diffraction utilizes the dependency of the atomic scattering factors f ′ and f ′′ of the energy of the radiation, especially close to the element‐specific absorption edges. In the MEAD technique, individual Bragg peaks are tracked over an absorption edge. The intensity changes depending on the structure factor can be highly characteristic for Miller indices selected for a specific structural problem, but require very exact measurements. Beamline KMC‐2 at synchrotron BESSY II, Berlin, has been recently upgraded for this technique. Anomalous X‐ray powder diffraction and XAFS compliment the data. Application of this technique confirmed established cation distribution in Cu 2 ZnSnSe 4 (CZTSe) and Cu 2 FeSnS 4 (CFTS). In contrast to the literature, cation distribution in Cu 2 ZnSiSe 4 (CZSiSe) is shown to adopt a highly ordered wurtz‐kesterite structure type.