Temperature-dependent nuclear magnetic resonance inCuInX2 (X=S,Se,Te)chalcopyrite-structure compounds

The NMR spectra of ${}_{}{}^{63}{}_{}{}^{}\mathrm{Cu}$ and ${}_{}{}^{115}{}_{}{}^{}\mathrm{In}$ in CuIn${\mathrm{S}}_2$, CuIn${\mathrm{Se}}_2$, and CuIn${\mathrm{Te}}_2$ have been measured between room temperature and 550°C. The effects of motional narrowing and of phase transitions on the shape and width of the absorption spectra were evaluated. In all three compounds, the absorption signal of ${}_{}{}^{63}{}_{}{}^{}\mathrm{Cu}$ shows motional narrowing. For ${\mathrm{Cu}}_{1.00}$ ${\mathrm{In}}_{1.00}$ ${\mathrm{S}}_{2.00}$ the mean jump frequency of the ${\mathrm{Cu}}^{+}$ ions, $\nu \left({\mathrm{Cu}}^{+}\right)$, is $2\times {10}^{13}\exp [-\frac{(1.25\mathrm{}\pm 0.10 \mathrm{eV})}{\mathrm{kT}}]$ ${\mathrm{s}}^{-1\mathrm{}}$. For both CuIn${\mathrm{Se}}_2$ and CuIn${\mathrm{Te}}_2$, $\nu \left({\mathrm{Cu}}^{+}\right)$ is about 3×${10}^3$ ${\mathrm{s}}^{-1\mathrm{}}$ at 350°C. In copper-deficient ${\mathrm{Cu}}_{0.96}$ ${\mathrm{In}}_{1.02}$ ${\mathrm{S}}_{2.00}$ no motional narrowing of the ${}_{}{}^{63}{}_{}{}^{}\mathrm{Cu}$ absorption was observed up to 550°C. However, the ${}_{}{}^{63}{}_{}{}^{}\mathrm{Cu}$ line shape in CuIn${\mathrm{S}}_2$ depends on the copper-to-indium ratio. A line-shape analysis as a function of composition shows that, at 450°C, CuIn${\mathrm{S}}_2$ exists in the composition range between ${\mathrm{Cu}}_{1.00}$ ${\mathrm{In}}_{1.00}$