Introduction

By control of matter in the nanoscale, nanotechnology brings together processes and techniques that are used to research, design and manufacture materials, devices and systems. It enables management of characteristics such as material size, shape, morphology, chemical composition and molecular configuration for the improvement, or development of, new process and product properties.

Applications of nanotechnologies are expected to impact virtually every aspect of life and enable dramatic advances in communication, health, manufacturing, materials and knowledge-based technologies. There is a need to provide industry and researchers with suitable tools to assist with the development, application and communication of nanotechnologies.

A crucial objective is the harmonization of terminology and definitions, in order to promote common understanding and consistent usage across communities where nanotechnologies are being developed and used. In the context of the ISO 80004 series, “terminology” refers to:

a) a structured or conceptual presentation of vocabulary employed in nanotechnologies, and
b) assigned definitions for specific units of the language in this vocabulary.

This document presents terminology and definitions for core terms in this emerging vocabulary and serves as the foundation for a broader vocabulary constituted collectively by the ISO 80004 series.

As nanotechnologies continue to evolve, the terms and definitions to facilitate communications have become increasingly specific and precise. For many communities, the meaning of terms such as nanoscale, nanomaterial and nanotechnology are inferred by logical application of the SI unit of scale. The prefix 'nano-' specifically means a measure of 10⁻⁹ units and the nature of this unit is determined by the word that follows. In the ISO 80004 series, however, terms such as nano-object and nanoscale employ size and geometric boundaries to express fundamental and measurable aspects of nanomaterials. In the case of the term nanoscale, the definition acknowledges that the length range of nano-objects can fall outside the precise boundaries normally associated with the concept of scale, by indicating that the upper and lower boundaries are approximate.

The lower limit (approximately 1 nm) in the definition of nanoscale is introduced to avoid single and small groups of atoms, as well as individual molecules, from being designated as nano-objects or elements of nanostructures, which can be implied by the absence of a lower limit. It should also be recognized that fullerene molecules and single layer planar structures (e.g. graphene) that have dimensions below 1 nm are, in practice, considered to be nanomaterials because they are important building blocks for nanotechnology.

Further, size-dependent biological effects, specifically particle-cell interactions and environmental interactions related to nanotechnology, involve structures below 1 nm and above 100 nm. In addition to size, the complex interplay of parameters such as aspect ratio, core chemistry, agglomeration state, physical state, surface properties and others will influence biological and environmental interactions associated with nanostructured materials.

Terminology development is proceeding at an intensive pace and needs to be responsive to the needs of stakeholders. As knowledge expands, terminology will need to effectively convey not only the size and shape-based metrics of nanomaterials but also the performance-based/properties-based aspects of intentionally produced nano-objects and nanostructuredmaterials in their definitions.

It will be an on-going challenge to communicate complex concepts in definitions in a manner that is meaningful and practical for stakeholders in research, commercial applications, government and consumer communities. It is emphasized that the definition of “nanoscale” in the ISO 80004 series is a general descriptor serving to facilitate communication concerning nanotechnologies.

The development of core terms and their definitions has benefited from discussions over time concerning scientific, regulatory and consumer usage. The science is still emerging, as is the capacity to measure and characterize nanomaterials or more generally matter in the nanoscale. Care needs to be taken to ensure the latest scientific information is incorporated into the terminology as it becomes available. It is important to acknowledge that the associated terms and their definitions will likewise follow an evolutionary path.

Many of the definitions in this document are determined to be in harmony with a framework and hierarchical system of terminology for nanotechnologies. Furthermore, it is also important to recognize that articles fabricated to contain nanomaterials are not necessarily nanomaterials themselves.

Nano-objects (e.g. nanoparticles, nanofibres and nanoplates), often occur in (large) groups, rather than as isolated or distinct entities. For reasons of surface energy, such coexisting nano-objects are likely to interact. The terms are not restricted with respect to physical size and shape. These terms are included for completeness and importance at the nanoscale.

Figure 1 illustrates the relationships between nanomaterial, nano-object and nanostructuredmaterial. However, this hierarchy is not intended to exclude the possibility for a nano-object to have internal or surface nanostructure. Figure 1 should therefore be considered as schematic or idealized.

Figure 1 — Nanomaterial framework

A number of other parameters in addition to size and shape are also intrinsic to the function and phenomena exhibited by nano-objects (see Figure 2). These parameters include composition, morphology, crystalline structure and surface features, which can all have a major influence on the key nanoscale phenomena exhibited by nano-objects. Such phenomena include magnetic, optical, catalytic, electronic and other properties.

Figure 2 — Schematic diagrams showing some shapes for nano-objects


a) Nanoparticle (3 external dimensions in the nanoscale)	b) Nanofibre (2 external dimensions in the nanoscale)	c) Nanoplate (1 external dimension in the nanoscale)

There is a hierarchical relationship between many of the different terms in this document, elements of which are shown in Figure 3.

Figure 3 — Fragment of hierarchy of terms related to nano-objects

Nanostructured materials are characterized by internal structures or surface structures at the nanoscale. Nano-objects (material with one, two or three external dimensions in the nanoscale) can be nanostructured.

A material should not be classified as nanostructured based solely on its crystalline properties (three-dimensional arrangements of atoms or molecules forming a crystallite, short range order of atoms in amorphous or quasi-amorphous phases, grain boundaries, intragranular interfaces, dislocations, etc.). In contrast, materials with a grain size distribution having a significant fraction of grains in the nanoscale (nanocrystalline), voids and pores in the nanoscale, or precipitations in the nanoscale (i.e. nano-objects in a solid matrix) are sufficient features for materials to be classified as “nanostructured”. Similarly, almost all materials always have surfaces with morphological and chemical heterogeneities in the nanoscale. Only surfaces that have been intentionally modified or textured to have morphological or chemical heterogeneities in the nanoscale qualify materials as “nanostructured”.

Five categories of nanostructured materials are covered in this document (see Figure 4):

a) nanostructured powder;
b) nanocomposite;
c) solid nanofoam;
d) nanoporous material;
e) fluid nanodispersion.

For some of these five categories, a number of subcategory terms are also defined. The category and subcategory terms are not comprehensive; additional categories and subcategories will be added in later revisions of this document.

Figure 4 — Categories of nanostructured materials defined in this document

The terms coating, layer, film and others that are related can be grouped by distinguishing between coatings, layers and films having a thickness in the nanoscale (i.e. external dimension in the nanoscale) and those having internal structures in the nanoscale (e.g. nanostructured coatings, nanocomposite coatings, dispersion coatings with dispersed nano-objects). Following the hierarchy established in this document which describes nanomaterial by the two categories ’nano-objects’ and ’nanostructured material’ the terms nanolayer, nanocoating, and nanofilm are assigned to ’nano-objects’ and the terms nanostructured layers, coatings and films are assigned to nanostructured material (see Figure 5). It is noted that nano-objects (including nanolayers, nanocoatings and nanofilms), can be elements or parts of a larger nanostructured material.

Figure 5 — Assigning the terms nanolayer, nanocoating, nanofilm to “nano-objects” and the terms nanostructured layers, coatings, and films to "nanostructured material" following the hierarchy of nanomaterial terms

Some of the terms defined in this document are also used in other industries. Keeping in mind their special applications, these industries can have slightly different definitions for those terms. In the case of

— pigments, dyestuffs and extenders, ISO 18451‑1 can be consulted,

— paints and varnishes, ISO 4618 can be consulted, and

— cleanrooms and associated controlled environments, ISO 14644‑3 can be consulted.

These references are available in the ISO online browsing platform.

BS EN ISO 80004-1:2023

Nanotechnologies. Vocabulary - Core vocabulary

Current

Published:

31 Aug 2023