What term is used for materials that are between 1 nanometer and 100 nanometers in size?

The term "nanoscale materials" refers specifically to materials that are within the size range of 1 nanometer to 100 nanometers. This size classification is significant because materials at the nanoscale exhibit unique physical and chemical properties that differ from those of larger-scale materials. This unique behavior is often attributed to the high surface area to volume ratio, which can result in enhanced reactivity, strength, and electrical characteristics.

In contrast, pico-materials, which are smaller than 1 nanometer, are not typically referred to in the same context as nanoscale materials. Micro-materials refer to those in the range of 1 micron to 100 microns, which falls outside the definition of nanoscale. Bulk materials are much larger than 100 nanometers and refer to conventional materials that do not exhibit nanoscale properties. Thus, "nanoscale materials" is the most accurate and relevant term to describe materials within the specified size range.