Particle of @G02600@ of any shape with an @E02191@ of approximately \(1\) to \(100\ \text{nm}\).
Source: PAC, 2007, 79, 1801. (Definitions of terms relating to the structure and processing of sols, gels, networks, and inorganic-organic hybrid materials (IUPAC Recommendations 2007)) on page 1807 [Terms] [Paper]