Diffuse x-ray scattering from ${\mathrm{La}}_{2\mathrm{-}\mathit{x}}$${\mathrm{Sr}}_{\mathit{x}}$${\mathrm{NiO}}_4$ and ${\mathrm{La}}_{2\mathrm{-}\mathit{y}}$${\mathrm{Sr}}_{\mathit{y}}$${\mathrm{CuO}}_4$

We use synchrotron x-ray scattering from ${\mathrm{La}}_{1.8}$ ${\mathrm{Sr}}_{0.2}$ ${\mathrm{NiO}}_4$ and ${\mathrm{La}}_{1.925}$ ${\mathrm{Sr}}_{0.075}$ ${\mathrm{CuO}}_4$ to establish a direct relationship between carriers due to Sr doping and strong diffuse scattering. In the nickelate the scattering is peaked at the fourfold symmetric satellite positions (±δ,±δ,l), where the basal-plane coordinate δ varies with the out-of-plane coordinate l of the momentum transfer. A similar scattering pattern is observed in the cuprate but with smaller values for δ.