Poudre (Fr). Pulver (Ge). Polvere (It). Polvo (Sp). Порошок (Ru).
A powder is a large number of crystallites or particles (grains, agglomerates or aggregates; crystalline or non-crystalline) irrespective of any adhesion* between them and thus can be a loose powder, a solid block, a thin film or even a liquid. An ideal powder is represented by a virtually unlimited number of sufficiently sized, randomly oriented and spherical crystallites.
In the Pharmaceutical industry (for example), an Active Pharmaceutical Ingredient (API) is produced (in general) as a nano powder (crystalline or amorph). Crystalline nano powders are characterized using a widespread technique known as XRPD (X-ray Powder Diffraction). This analytical method provides a fingerprint which is unique for each pure nano powder system. Electron Diffraction (ED) is a new upgrowing technology which indeed is not only able to deliver such a fingerprint, but even more. An electron diffractometer will disrupt in the future the way chemical analysis is done for nano powders.
Professor Mauro Gemmi (IIT Pisa) has highlighted the limitations of present state of research via powder diffraction mode and how the emergence of a dedicated instrument for ED would be a breakthrough.
1 “Powder”, accessed on September 21, 2020 , https://dictionary.iucr.org/Powder
2 “Adhesion”, accessed on September 21, 2020, https://en.wikipedia.org/wiki/Adhesion