CHARACTERIZATION OF METAL AGGREGATES BY SCANNING MICROSCOPY - PARTICLE SIZES AND SPACE DISTRIBUTION IN INTERMETALLIC PARTICLES

Various metal aggregates prepared using ionizing radiation were studie d by microscopy techniques. A metal deposit onto a carbon felt obtaine d from solutions containing Pt and Ru was shown to consist of nanometr ic particles containing both metals. Another study deals with a subnan ometric silver aggregate. The nuclearity of the aggregate was studied by scanning tunneling microscopy (STM). Additional information from pu lse radiolysis experiments allowed the determination of the Ag-7(3+) s toichiometry. The third material consisted of Ag/Pd submicron powders (70/30 or 75/25 % w/w) used in electronics, and made of spherical bime tallic grains; X-ray diffraction showed segregation. The spatial distr ibution of each metal was obtained by combining space-resolved X-ray m icroanalysis in the transmission electron microscope, X-ray photoelect ron spectroscopy and secondary ion mass spectrometry. Each grain was s hown to be core/rind structured (core: pure Ag; rind: 10-15 nm thick 1 1% Ag/89 % Pd w/w alloy).