X-ray diffraction investigation on Cu2ZnSiSe4 single and polycrystalline crystals

Cu2ZnSiSe4 belong to the adamantine family of quaternary chalcogenides crystallizing in the wurtzstannite structure. Recent ab-initio calculations show, that the lowest energy structure of Cu2ZnSiSe4 is the wurtzkesterite type structure in contrast to wurtzstannite type, usually obtained in experiments. To clarify this issue a structural study on single crystals of Cu2ZnSiSe4 was performed for the first time. The structural characterization of the single crystals was carried out by X-ray diffraction at two different temperatures - room temperature and 150 K. The XRD data analysis shows, that Cu2ZnSiSe4 single crystals adopt the orthorhombic wurtzstannite type structure (space group Pmn2(1)) and lattice parameters a = 7.809 angstrom, b = 6.778 angstrom, c = 6.447 angstrom at 150 K, and lattice parameters a = 7.821 angstrom, b = 6.734 angstrom, c = 6.453 angstrom at room temperature were derived. The structural parameters were confirmed for the polycrystalline Cu2ZnSiSe4 bulk sample.