Luminescence and magnetic properties of copper-deficient $\mathrm{Cu_{2-x}^+Cu_{x/2}^{2+}\square_{x/2}ZnSnS_4}$ $(0\lt x \leqslant 0.30) $ solid solutions with a kesterite structure

The copper-deficient solid solutions $\mathrm{Cu_{2–y}ZnSnS_4}$ $(0 \lt y \leqslant 0.45)$ with a kesterite crystal structure were synthesized and their unit cell parameters at different values of $y$ were determined. Based on magnetometry it was found that the crystal lattice of $\mathrm{Cu_{2-x}^+Cu_{x/2}^{2+}\square_{x/2}ZnSnS_4}$ $(0\lt x \leqslant 0.30) $ contains copper in the oxidation states 2+ and 1+. A band at 1.27eV in the cathodoluminescence spectra of the $\mathrm{Cu_{2-x}^+Cu_{x/2}^{2+}\square_{x/2}ZnSnS_4}$ solid solutions at 78K is due to the $\mathrm{Cu^{2+}\cdot V_{Cu}}$ associates of defects.