Challenges and structural characterization of the solid solution Cu2Zn(Gex Si1-x) Se4

The quaternary chalcogenides Cu
₂
ZnSiSe
₄
and Cu
₂
ZnGeSe
₄
crystallize in the orthorhombic wurtz-stannite and tetragonal kesterite type structures, respectively. To investigate thestructural transformation within the solid solution series Cu
₂
Zn(Ge
_x
Si
_1-x
) Se
₄
a systematic structural study was performed. Polycrystalline samples, prepared by solid state reaction, show a single quaternary phase as analyzed by WDX spectroscopy. Structural parameters of the mixed crystals were obtained using powder X-ray diffraction. It can be shown that apart from Cu
₂
ZnSiSe
₄
, Si-rich mixed crystals of this series adopt the wurtzstannite type structure. The lattice parameters are in consistency with Vegard's law and increase with increasing Ge content.