The majority of QENS studies on proton-conducting perovskites have been per­formed with the use of either time-of-flight or backscattering methods [58]. These methods give access to the picosecond timescale, extended to * 1 nanosecond in some cases, in which local diffusional-dynamics have been observed, although data have also been interpreted in terms of translational diffusion [59, 60]. The first work was done by Hempelmann et al. [32, 33] for SrYb0.05Ce0.95O2.9-75, where rotational — diffusional motion of the — OH group was observed. These results gave support for molecular-dynamics simulations, which suggested that the proton-conduction mechanism in hydrated perovskites involves proton jumps between neighbouring oxygens and rotational diffusion of the — OH group between proton transfers [28-31]. Later, Groh et al. [61] reported on localized diffusional proton-dynamics in BaZr085M0.15O2.925 (M = Y, In, and Ga), Pionke et al. [59] reported the proton self­diffusion constant for protons in Ba[Ca0.39Nb0.6i]O2.9i, and similarly, Wilmer et al. [62] presented results for BaY0.i0Zr0.90O2.95. Braun et al. [60], reported two dif­ferent activation energies for proton diffusion in BaY0.i0Zr0.90O2.95 at different temperature ranges, Colomban et al. [63] reported a change in local proton — dynamics across a structural phase transition of (Ba/Sr)Zrj_xLnxO3_d, whilst Karlsson et al. [64] reported a relatively-small difference in the activation energy for local proton-dynamics depending on the choice of dopant atom in BaM0.i0Zr0.90 O2.95 (M = Y and Sc). This collection of examples illustrates the success of time — of-flight and backscattering methods to study the local diffusional proton-dynamics in proton-conducting oxides. However, to reach the long time-scale of several nanoseconds needed to study the long-range translational proton-diffusion on an atomic length-scale (* 1-30 A), another QENS method, namely neutron spin-echo (NSE) spectroscopy, is required.