Average and local structures of amorphous Pd75Si25 alloy analyzed by modern electron diffraction techniques

In order to develop electron diffraction structure analysis methods for both average and local structures of amorphous alloys, halo-electron diffraction intensity and nano-probe electron diffraction intensity analyses were performed for amorphous Pd75Si25 alloy thin firms. In the halo-diffraction intensity analysis, intensities were recorded using ‘imaging plates’ and inelastic intensities were removed by using an energy-filter. Atomic Pd-Pd and Pd-Si distances and the number of Pd-Pd nearest neighbors were determined from the atomic pair distribution function analysis (PDF). To analyze local structure, especially medium-range order (MRO), nano-probe electron diffraction with a probe size of 1–1.5 nm was applied with the help of high-resolution electron microscopy (HREM) observation. It was found that the structure of MRO is hexagonal of the Pd2Si-type with lattice parameters = 0.715 and c = 0.312 nm. Atomic distances of Pd-Pd and Pd-Si and the number of Pd-Pd nearest neighbors obtained from the nano-diffraction structure analysis were in good agreement with those from the PDF analysis.