Finally, we discuss the implications of the NMR data on the vacancy-assisted dynamics mechanisms. A QENS investigation on the hydride conduction dynamics suggested that at low temperatures ( 250 K) the hydride ion hopping occurs between the nearest oxygen vacancy located orthogonally to the hydride ion, whilst at high temperatures (> 400 K) the hydride ion jumps to the next-nearest oxygen vacancy located vertically or horizontally with respect to the hydride ion in the lattice. The study also reported that for both mechanisms the hydride ion mean residence times are of the order of 1 100 ps, which indicates that the process is in the fast exchange regime on the NMR timescale and fully averaged tensor parameters would be detected.