1、 Reference number ISO/TR 14187:2011(E) ISO 2011TECHNICAL REPORT ISO/TR 14187 First edition 2011-08-15 Surface chemical analysis Characterization of nanostructured materials Analyse chimique des surfaces Caractrisation des matriaux nanostructurs ISO/TR 14187:2011(E) COPYRIGHT PROTECTED DOCUMENT ISO 2
2、011 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISOs member body in the co
3、untry of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2011 All rights reservedISO/TR 14187:2011(E) ISO 2011 All rights reserved iiiContents Page Foreword iv I
4、ntroduction . v 1 Scope 1 2 Terms and definitions . 1 3 Symbols and abbreviated terms 1 4 Characterization of nanostructured materials with surface analysis methods 3 4.1 Introduction 3 4.2 Electron Spectroscopies (AES and XPS) 6 4.2.1 Surface functionalization and product formation 7 4.2.2 Presence
5、 of contamination and coatings . 8 4.2.3 Orientation of surface molecules 8 4.2.4 Coating or layer thickness . 8 4.2.5 Near-surface elemental distribution 10 4.2.6 Particle size 10 4.2.7 Particle location, composition and shape 11 4.2.8 Other properties: electronic characteristics and surface acidit
6、y . 11 4.3 Ion-beam surface analysis methods (SIMS and LEIS) . 12 4.3.1 SIMS and examples of SIMS applications . 12 4.3.2 Low energy ion scattering and applications to nanomaterials 13 4.4 Scanning probe microscopy 14 4.5 Surface characterization of carbon nanostructures 15 5 Analysis considerations
7、, issues and challenges associated with characterization of nanostructured materials: Information for the analyst. 15 5.1 Introduction 15 5.2 General considerations and analysis challenges 16 5.3 Physical properties . 17 5.4 Particle stability and damage: influence of size, surface energy and conflu
8、ence of energy scales 18 5.4.1 Crystal structure 18 5.4.2 Damage and probe effects . 19 5.4.3 Time and environment 19 5.5 Sample mounting and preparation considerations . 24 5.6 Specific considerations for analysis of nanostructured materials using XPS, AES, SIMS and SPM . 24 5.6.1 Introduction 24 5
9、.6.2 Issues related to application of XPS to nanomaterials . 24 5.6.3 Issues related to the application of AES to nanostructured materials 27 5.6.4 Issues related to application of SIMS to nanoparticles . 27 5.6.5 Issues related to the application of scanning probe methods to nanoparticles 29 6 Gene
10、ral characterization needs and opportunities for nanostructured materials . 29 Bibliography 31 ISO/TR 14187:2011(E) iv ISO 2011 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of
11、 preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental
12、, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main
13、task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. In ex
14、ceptional circumstances, when a technical committee has collected data of a different kind from that which is normally published as an International Standard (“state of the art”, for example), it may decide by a simple majority vote of its participating members to publish a Technical Report. A Techn
15、ical Report is entirely informative in nature and does not have to be reviewed until the data it provides are considered to be no longer valid or useful. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held respon
16、sible for identifying any or all such patent rights. ISO/TR 14187 was prepared by Technical Committee ISO/TC 201, Surface chemical analysis, Subcommittee SC 5, Auger electron spectroscopy. ISO/TR 14187:2011(E) ISO 2011 All rights reserved vIntroduction As engineered nanomaterials of many types play
17、an increasing role in many different technologies 1, international organizations (including ISO, ASTM, the International Bureau of Weights of Measures (BIPM), Consultative Committee for Amount of Substance: Metrology in Chemistry (CCQM) and the Organization for Economic Cooperation and Development (
18、OECD)1 are working to identify critical properties 2 and measurements that must be understood to adequately define the nature of the materials being used. An inherent property of any nanostructured material, whether a particle, fibre or other object, is that a large percentage of the material is ass
19、ociated with a surface or interface. Therefore, surface composition and chemistry have been identified as being part of a minimum set of chemical parameters need to characterize nanomaterials and it would naturally seem that the wide range of tools developed for surface characterization could or sho
20、uld be routinely applied to these materials. Two different issues, however, have limited the impact of traditional surface analysis tools in some areas of nanoscience and nanotechnology. First, many of the tools do not have sufficient spatial resolution in three dimensions needed to analyse individu
21、al nanostructured materials (or, equivalently, variations of composition within that material). For this reason, some researchers do not consider application of the tools even though they can often provide very important information. Second, surface analytical (and other) tools are often applied to
22、nanostructured materials without appropriately considering several analytical challenges or issues that these materials present. Such challenges include environmentally altered behaviours of nanoparticles (including effects of making measurements in vacuum), time-dependent characteristics of nanostr
23、uctured materials, the influence of particle shape on analysis results, and the increased possibility of altering the structure or composition of the nanomaterial by the incident radiation (typically electrons, X-rays, or ions) during the analysis. This Technical Report gives information on these im
24、portant issues. The report first describes the types of information that can be obtained about nanostructured materials, sometimes using analytical approaches beyond those in standard applications. Second, the report examines the technical challenges generally faced when applying surface analysis to
25、ols (and often other tools) for characterization of nanostructured materials as well as those specific to each technique. Because of the expanding use of nanostructured materials in research, development, and commercial applications as well as their natural presence in air and ground water, there is
26、 an increasing need to understand the properties and behaviours of nanostructured materials as they are synthesized or as they evolve in a particular environment. The novel and unusual properties of nanostructured materials excite scientists, technologists and the general public. However, the someti
27、mes surprising properties of many of these materials raise analysis or characterization issues that sometimes are unexpected by analysts, scientists, and production engineers 3-5. Potential health and environmental concerns related to materials with unusual or unique properties increase the need to
28、understand the chemical, physical and biological properties of these materials throughout their life cycle. It is now recognized that some early reports on the properties of nanoparticles and other nanostructured materials, including their toxicity and environmental stability, were based on inadequa
29、te characterizations 6. In some cases, important characterizations appear not to have been attempted or reported 7, 8. A March 2006 article in Small Times magazine described a workshop designed to identify roadblocks to nanobiotech commercialization 6 at which several experts reported that many of t
30、he important physical characteristics needed to understand the physical and chemical properties of nanoparticles were not reported and apparently often unmeasured, especially in assessments of particle toxicity. The article further notes that the changes that these particles undergo when exposed to
31、the environment where they are stored or used are especially important and usually unknown. In many cases, nanoparticles are coated with surfactants or contaminants, and these are often not well characterized and sometimes not adequately identified. As a result, the validity of the conclusions may b
32、e questionable. Inadequate characterization of the surface chemistry of nanoparticles has been identified as one of the areas where appropriate characterization is often lacking 4, 8. One of the definitions of a nanostructured material is that, in at last one dimension, the size of the object or str
33、ucture must be 100 nm or less. Considerable attention is being given to the characterization of nanosized- objects (particles, rods or other shapes) that might be released into the environment and a set of minimum characterization requirements for nanoparticles for use in toxicity studies has been i
34、dentified 2. However, the needs for nanomaterials characterization include the wide variety of nanostructured materials that are used in ISO/TR 14187:2011(E) vi ISO 2011 All rights reservedcomputers, as sensors, in batteries or fuel cells and many other types of applications. Nonetheless, the minimu
35、m characterization requirements for nanoparticles can be generalized to a wider range of materials and potential applications as shown in Table 1. Surface-analysis methods of various forms (described later) can provide information that relates to many elements in Table 1 including those that appear
36、obvious (such as surface composition and chemistry) but also includes particle or component size, presence of surface impurities, nature of surface functionality (including acidity), surface structure/morphology, near-surface variation of composition (both laterally and with depth, coating/film thic
37、kness, and electronic properties of nanostructures/films. Surface characterization is only a subset of several nanomaterials analysis needs that are being examined by ISO/TC 229. This report on surface chemical analysis methods prepared by ISO/TC 201/SC 5 has been prepared in coordination with the o
38、verall characterization needs identified by experts in TC 201 and TC 229 as well as awareness of the objectives being addressed by ISO/TC 229. This Technical Report describes the information that can be obtained (and by which techniques), and examines some of the issues and challenges faced when per
39、forming such analyses. Table 1. Physical and chemical properties for characterization of nanostructured materials Items in bold font are properties for which surface chemical analysis can provide useful information, as described in this Technical Report. _ What does the material look like? Particle/
40、grain/film/structural unit size(s) /size distribution Grain, particle, film morphology (shape, layered, roughness, topography) Agglomeration state/aggregation (e.g., do particles stick together) What is the material made of? Bulk composition (including chemical composition and crystal structure) Bul
41、k purity (including levels of impurities) Elemental, chemical and/or phase distribution (including surface composition and surface impurities) What factors affect how a material interacts with its surroundings? Surface area Surface chemistry, including reactivity, hydrophobicity Surface charge Overa
42、rching considerations to take into account when characterizing engineered nanomaterials (for toxicity studies and other applications): Stabilityhow do material properties (especially the surface composition, particle agglomeration, etc.) change with time (dynamic stability), storage, handling, prepa
43、ration, delivery, etc.? Include solubility and the rate of material release through dissolution Context/mediahow do material properties change in different media or during processing (environmental effects); i.e., from the bulk material to dispersions to material in various biological matrices? (“as
44、 administered” characterization is considered to be particularly important) Where possible, materials should be characterized sufficiently to interpret functional behaviours. For toxicology studies, information is required on the response to the amount of material against a range of potentially rele
45、vant dose metrics, including mass, surface area, and number concentration _ This table is adapted from 2. The recommendations in the initial table were developed at a workshop on ensuring appropriate material characterization in nanotoxicology studies, held at the Woodrow Wilson International Center
46、 for Scholars in Washington, DC, USA, between 28 October and 29 October, 2008; http:/www.characterizationmatters.org. TECHNICAL REPORT ISO/TR 14187:2011(E) ISO 2011 All rights reserved 1Surface chemical analysis Characterization of nanostructured materials 1 Scope This Technical Report provides an i
47、ntroduction to (and some examples of) the types of information that can be obtained about nanostructured materials using surface-analysis tools (Section 4). Of equal importance, both general issues or challenges associated with characterizing nanostructured materials and the specific opportunities o
48、r challenges associated with individual methods are identified (Section 5). As the size of objects or components of materials approaches a few nanometres, the distinctions among “bulk”, “surface” and “particle” analysis blur. Although some general issues relevant to characterization of nanostructure
49、d materials are identified, this Technical Report focuses on issues specifically relevant to surface chemical analysis of nanostructured materials. A variety of analytical and characterization methods will be mentioned, but this report focuses on methods that are in the domain of ISO/TC 201 including Auger Electron Spectroscopy, X-ray photoel
