Single Crystal Quasielastic Neutron Study of Ionic Conduction in Cu2Se

Ionic conductivity plays a role in a wide range of energy technologies such as solid-state batteries, super capacitors, and fuel cell technology. We investigated ionic conductivity mechanisms in Cu2Se, a fast ion conductor, above its transition point at T = 400 K using single crystal Quasi-Elastic Neutron Scattering measurements covering volumes of reciprocal space, known as 4D-QENS. The Chudley-Elliott jump diffusion model was employed to analyze the QENS linewidth broadening, providing insights into the mechanisms of ionic conductivity, such as average residency times and diffusion coefficients. Different neutron beam energies were used in our investigations which aided in the separation of incoherent scattering and coherent scattering. This separation enabled us obtain details about the vacancy hopping and the correlated diffusion mechanisms which contribute to the ionic conductivity in this fast ion conductor which will be discussed.