Formation of Bismuth Nanoparticles on Nanoporous Substrates.

Substrates with a layer of anodized aluminum oxide are obtained by one-stage and two-stage anodization. The samples have different porosity in volume and on the surface. Bismuth nanoparticles are obtained by thermal evaporation in an argon medium by condensation onto substrates with a layer of anodized aluminum oxide. The distribution of sizes, shapes, and the quantity of nanoparticles and microparticles is studied from images obtained using a scanning electron microscope. The largest number of nanoparticles (21%) on the sample with a surface layer of aluminum oxide without pores is characterized by a diameter of 70 nm. It is assumed that the presence of pores on the surface affects the migration of deposited atoms and particles of bismuth melt until stable condensation centers are formed. The presence of pores with a diameter from 20 to 100 nm leads to a decrease in the diameter of the most common bismuth nanoparticles from 80 to 40 nm. Nanoparticles with a diameter of 90 nm predominate (25%) in the sample with pores with a diameter from 60 to 220 nm. The largest number of spherical crystallites on all substrates has a diameter of 110 nm. It is found that a uniform distribution of particles is obtained for the sample, whose surface was not subjected to chemical polishing. [ABSTRACT FROM AUTHOR]