Figure shows the XRD data for citrate-Au@NiB core-shell nanoparticle and NiB nanoparticles. Peak fitting showed that the first amorphous peak occurs at a q-spacing of 3.08 Å -1 for citrate-Au@NiB nanoparticles and 3.16 Å -1 for NiB nanoparticles. This indicates that the shell on the citrate-Au core is stretched under tensile forces, which we attribute to the surface curvature of the core nanoparticle. The citrate-Au core XRD peaks match with the bulk Au peak positions and the observed peak broadening is due to the small nanoparticle size. Figure shows the in situ XRD high pressure compression of citrate-Au@NiB core-shell nanoparticles. The nanoparticles were compressed from 0.6 GPa to 55 GPa under quasi-hydrostatic loading. The XRD peaks for Au core are present throughout the pressure range, and the peaks shift towards the right with increasing pressure indicating the lattice compression for Au core. The amorphous XRD peaks for NiB were overlapping with the Au crystalline peaks. The NiB coating stays amorphous up to 55 GPa pressure.