Study of the dynamics of lattice of copper selenide by the NMR method.

The article presents the results of investigations of copper selenide Cu_1.75Se using the NMR method. The ⁷⁷Se NMR spectrum for Cu_1.75Se is a single line with full width at half maximum (FWHM) of 4 kHz at the temperature of 250 K. Within the temperature range of 200-450 K, the rates of transverse and longitudinal relaxation are equal. This phenomenon is mainly typical of a liquid, where the homonuclear dipole-dipole interaction is effectively averaged due to the Brownian motion of molecules. In this case, the main mechanism that averages the dipole-dipole interaction is the motion of copper ions. Below 200 K, copper ions are partially localized due to the phase transition, and the behavior of the spin-spin and spin-lattice relaxation rates (as well as their values) are different. [ABSTRACT FROM AUTHOR]