Off-stoichiometric CZTS: Neutron scattering investigations on mechanochemically synthesized powders

• Off-stoichiometric CZTS powder samples of B- and C-type were successfully synthesized.
• Neutron scattering measurements allowed full cation distribution analyses.
• In B-type CZTS ZnCu and ZnSn, in C-type materials CuZn and SnZn point defects were observed.
• 30–35% CuZn-ZnCu anti-site defect pairs on Wyckoff positons 2c and 2d are present in both off-stoichiometric types.

In this work a series of B- and C-type off-stoichiometric CZTS samples was prepared by a mechanochemical synthesis route. For structural characterization X-ray diffraction measurements were performed. Furthermore, compositional analyses of the powder samples were carried out by means of wavelength-dispersive X-ray spectroscopy (WDS). For detailed cation distribution analyses of two off-stoichiometric single-phase samples neutron diffraction methods were used. The method of the average neutron scattering length was applied revealing the occurrence of ZnCu, CuZn, and ZnSn point defects in the Cu-poor/Zn-rich sample (B-type, Cu1.95Zn1.09Sn0.96S4.00), whereas for the Cu-rich/Zn-poor sample (C-type, Cu2.04Zn0.95Sn1.01S4.00) ZnCu, CuZn, and SnZn defects are suggested.