Size-Dependent Lattice Distortion in ε‑Ag₃Sn Alloy Nanoparticles

In this study, the crystallographic structure of orthorhombic ε-phase Ag₃Sn nanoparticles with different sizes between 7 and 120 nm was studied by X-ray diffraction, and the influence of the size and the composition of the nanocrystals on the lattice parameters were investigated. Rietveld refinement was used to confirm the orthorhombic (space group <i>Cmcm</i>) crystal structure and to determine the lattice parameters and the size of the crystals for all nanoparticle samples. We found an anisotropic decrease of the lattice parameters which furthermore depends on the size of the crystallites. Etching the nanoparticles with sulfuric acid allows us to control the Ag/Sn ratio of the Ag₃Sn nanoparticle samples. The lattice parameters decrease for higher Ag/Sn ratio