To determine the localized strain of the LLZTO after implantation, scanning precession electron diffraction has been performed (Supplementary Figure ). The diffraction patterns and the simulated patterns of LLZTO are generally in good agreement (see Supplementary Figure5b-c), though some parts of the sample are only partially crystalline resulting in slightly divergent diffraction spots. Hence, the resolution of the electron diffraction spots has not been high enough to get reliable strain values. Therefore, cross-sectional scanning nano XRD was used on a mechanically thinned sample to quantify the residual stress depth-profile created by the implanted ions. The 80 nm X-ray spot size allows the measurement of residual stresses and crystallinity with a high spatial resolution. The depth-dependent XRD patterns (Figure ) confirm a partial amorphization of the top 700 nm as indicated by the broad diffuse scattering peak centered around 18 degrees 2Θ and the inversely proportional decrease of reflections related to the LLZTO phase, as opposed to the underlying region below. From the orientation-dependent peak position a depth-resolved residual stress profile can be calculated. At a depth of 850 nm below the surface, just below the amorphized layer, a compressive stress peak up to approx. -700 MPa was evaluated, whereas throughout the rest of the layer the stress level does not exceed approx. -250 MPa. The slight waviness of the residual stress depth profile is stemming from the fact that the recorded XRD patterns lie somewhere between those corresponding to a singlecrystal and fully powder-like poly-crystal, resulting in residual stresses corresponding to the transition range between 1 st and 2 nd order stress, i.e., including some degree of grain-to-grain stress variation.