For the Synchrotron measurements two implanted Li6.4La3Zr1.4Ta0.6O12 polycrystalline sample crosssections were thinned down to a final thickness of around 80 µm by conventional mechanical polishing as mentioned above. The cross-sectional scanning X-ray nanodiffraction (CSnanoXRD) experiment was carried out at the nanofocus end station of the Microfocus beamline ID13 at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France. The sample was scanned by a monochromatic X-ray beam of 13 keV photon energy focused to approx. 80 nm spot size by multilayer Laue lenses, applying a scanning step of 50 nm in the direction perpendicular to the implanted surface. 40 depth-profile scans spaced 1 µm apart were averaged in order to counteract the poor diffraction statistics that result from the combination of small X-ray beam, thin sample slice and comparatively large grain size of the probed material. Diffraction patterns were acquired in transmission on a Dectris Eiger X 4M two-dimensional (2D) X-ray detector placed 10.98 cm downstream of the sample with an exposure time of 50 ms. The exact detector position was calibrated by measuring a standard corundum reference powder, using the routines provided by the pyFAI software package. 2D diffraction patterns in the form of Debye-Scherrer rings were integrated azimuthally using the pyFAI software package and subsequently processed using custom python scripts for peak fitting with Pseudo-Voigt functions and strain/stress calculation. The evaluation of stress was based on the plausible assumption that there is no force acting perpendicularly on the free surface of the sample, which make the application of a sin² 𝜓-based method possible. In such a case, the only necessary input parameters are the elastic properties of the probed material, i.e. in this case the X-ray elastic constant . In summary, the CSnanoXRD experiment and the applied evaluation technique corresponds to earlier studies of thin films samples at the same beamline, for more details see Ref. [42].