Formation of droplets during annealing of Bi$_{2}$O$_{3}$ nanopowder obtained by pulsed electron beam evaporation in vacuum

Using a method of pulsed electron beam evaporation in vacuum was produced the mesoporous multiphase amorphous and crystal nanopowder of Bi$_{2}$O$_{3}$ with a specific surface area up to 23 sq.m/g. Influence of thermal annealing of powder (200 – 300$^\circ$C) in air is investigated. The formation of droplets with a size of 2 – 5 nm was found on the surface of all large nanoparticles that make up the framework 3D nanopowder agglomerates due to extrusion of liquid bismuth from the volume during cooling.