At sufficiently high temperature, diffusion processes start. This results in a conversion of the amorphous structure into an ordered lattice structure at different material-dependent temperature ranges. At the same time the dust is subject to the process of annealing. Due to thermally enhanced diffusion, the dust material gradually develops some order in the local arrangement of the atoms.
Lattice structure changes to a microcrystalline material.
Atom-size dependent diffusion leads to chemical fractionation, i.e. impurities may assemble at the surface or in inclusions. If annealing lasts sufficiently long even crystallization may start at critical nuclei. Laboratory study reveils which kind of crystalline minerals forms from an amorphous silicate produced by laser ablation or pyrolysis. Time of first indications for formation of an ordered structure. We found IR spectroscopy to be very sensitive to detect the presence of microcrystals.