Compaction of agglomerates of aerosol nanoparticles: A compilation of experimental data

The compacting behavior of agglomerated aerosol nanoparticles in the size range between 7 and 150 nm was investigated using available literature data. We observed a characteristic behavior, which can be described by three separate steps. When comparing the first step, the compaction from agglomerates into spherules, differences could be observed for nanoparticles of different materials. It is seen from the available data that smaller particles compact at lower temperatures. For most materials where data available (Ag, Au, Fe, W, PbS and SnO2), the compaction temperatures were found to lie in a temperature interval, between 1/3 and 1/2 of the bulk melting temperature. For the data available on TiO2, on the other hand, the compaction temperature corresponds to about 2/3 of the bulk melting temperature. Thus, a fundamental difference might exist in the sintering behavior of titania as compared with other materials. This difference may be attributed to a lower degree of cleanliness of the titania particles.