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Eingeladener Vortrag
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A layer of Sb atoms, implanted with an energy of 400 keV and a nominal dose of 5×1016 atoms/cm2 into a high purity silicon wafer, was certified for its areal density (atoms/cm2) using Rutherford backscattering spectrometry (RBS), instrumental neutron activation analysis (INAA) and inductively coupled plasma isotope dilution mass spectrometry (ICP-IDMS) and for its isotope ratio using INAA and ICP-IDMS. Excellent agreement between the results of the different independent methods was found. In the present work, the measurements of the homogeneity of the areal density of Sb, previously determined with RBS in spots having 1 mm diameter, are improved with synchrotron X-ray fluorescence analysis: Higher precision in even smaller sample spots allows to estimate a reduced inhomogeneity of the whole batch of samples of the order of only 0.4%. Thus the uncertainty of the certified value can further be reduced. Down to fractions of a chip with 0.3×0.4 mm2 area, the areal density is now certified as (4.81±0.06)×1016 Sb atoms/cm2, where the expanded uncertainty 0.06 (coverage factor k=2) corresponds to only 1.2%. The relative merits of the different analytical methods are discussed.
Adhesion and other mechanical behaviour of coatings is at present routinely tested in industry and research organisations using the scratch test. The test has been the subject of a European Standard prEN 1071-3:2000 established by the European Standards Committee CEN TC184 WG5. A previous European project on the development and validation of test methods for thin hard coatings—FASTE—revealed that uncertainties in the Rockwell C stylus tip shape represent a major source of error for the scratch-test method. Therefore a follow-up project—REMAST—was started to develop and certify a reference material as a quality control tool for the testing and qualification of scratch-test instruments. In addition, a considerable effort was devoted to improve the scratch stylus manufacturing process. This paper presents the results of the REMAST project. During a feasibility study, two candidate materials—titanium nitride (TiN) and diamond-like carbon (DLC) coatings both on high speed steel substrates—were evaluated. Because of the lower sensitivity to styli tip shape variations and higher data scatter observed for the TiN coating, DLC was chosen as the reference material to be certified. One thousand samples were produced, as well as qualified styli to carry out the certification campaign, including homogeneity and stability testing. Nine independent laboratories were involved in the certification exercise, and the data were statistically analysed to obtain the certified critical load values and their uncertainty ranges. A certified reference material BCR-692 is available for verification purposes. This presents three repeatable failure events at certified critical load intervals and can provide a good indication of overall scratch-test instrument performance, including stylus condition and calibration. It is also useful as a diagnostic tool, providing a means of sensitive monitoring of machine and stylus performance over extended periods. Considerable improvement of the quality of scratch styli was achieved by the strict control of all manufacturing steps.
The pore size analysis of solids is widely applied in chemical industries, materials engineering, ceramic production, environmental engineering, catalysis, chromatography, nanotechnology, and many other fields. In spite of several new methods used for determining the pore size distribution of meso- and macropores [see IUPAC Recommendations of 1994], mercury porosimetry has remained one of the most popular methods employed for the characterisation of porous materials. In this paper, a new way is described for the estimation of certified pressure-volume curves from experimental curves measured by different laboratories in connection with the certification of new reference materials for a comparatively low-pressure range of mercury intrusion (<2 MPa). Simultaneous confidence and prediction bands for the certified pressure-volume curves are constructed by bootstrapping.
The mass fraction of potassium hydrogen phthalate (KHP) from a specific batch was certified as an acidimetric standard. Two different analytical methods on a metrological level were used to carry out certification analysis: precision constant current coulometric and volumetric titration with NaOH. It could be shown that with a commercial automatic titration system in combination with a reliable software for the end-point detection it is possible to produce equivalent results with the same accuracy in comparison to a definite method handled by a fundamental apparatus for traceable precision coulometry. Prerequisite for titrations are that a high number of single measurement are applied which are calibrated with a high precision certified reference material.
Ethanol/water solutions as certified reference materials for breath alcohol analyzer calibration
(2010)
The Federal Institute for Materials Research and Testing (BAM), Germany, has issued a series of large volume ethanol in water certified reference materials (CRMs), primarily developed for the calibration of evidential breath alcohol analyzers in Germany. The certified parameter is the ethanol mass concentration at 20 °C. When used in a wet bath simulator, the solutions deliver gas samples that meet the requirements set by the Organization of Legal Metrology for calibration of breathalyzers. The materials were prepared gravimetrically by spiking of ethanol into water in single 5 L units. A complete uncertainty budget for the preparation process has been established. The purity of the commercial ethanol stock solution was identified to be the main source of uncertainty. For stability and homogeneity measurements and for the verification of the gravimetric mass concentration of the CRMs, a robust high-precision gas chromatography, with flame-ionization detection method for ethanol determination in aqueous samples was developed and validated. The good performance of this method has been demonstrated in several international comparisons organized by the Consultative Committee for Amount of Substance-Metrology in Chemistry at the International Bureau of Weights and Measures.
The certification of a boron carbide reference material for chemical composition is described. The mass fractions of 16 elements and two boron species are certified in an international interlaboratory comparison with 35 participating laboratories from six different countries. Beside chemical characterization the certification process includes homogeneity and stability testing of the candidate material boron carbide (type F360, 305M422). Details of the analytical methods used for chemical characterization and of the calculation of the uncertainties of the certified mass fractions are given. The new reference material ERM®-ED102 with certified mass fractions of 18 parameters (elements and species) and of the amount fraction of the isotope 10B is a valuable tool for laboratories working in the field of advanced ceramic materials analysis to improve their analytical results.
The certified reference material BAM-L200, a nanoscale stripe pattern for length calibration and specification of lateral resolution, is described. BAM-L200 is prepared from a cross-sectioned epitaxially grown layer stack of AlxGa1–xAs and InxGa1–xAs on a GaAs substrate. The surface of BAM-L200 provides a flat pattern with stripe widths ranging down to 1 nm. Calibration distances, grating periods and stripe widths have been certified by TEM with traceability to the length unit. The combination of gratings, isolated narrow stripes and sharp edges of wide stripes offers plenty of options for the determination of lateral resolution, sharpness and calibration of length scale at selected settings of imaging surface-analytical instruments. The feasibility of the reference material for an analysis of the lateral resolution is demonstrated in detail by evaluation of ToF-SIMS, AES and EDX images. Other applications developed in the community are summarized, too. BAM-L200 fully supports the implementation of the revised International Standard ISO 18516 (in preparation) which is based on knowledge outlined in the Technical Report ISO/TR 19319:2013.
Cyanides are among the most important inorganic pollutants to be tested and monitored in environmental compartments. They can be distinguished and determined as free cyanide, weak acid dissociable cyanide or as total cyanide. However, in any case obtained, measurement results are operationally defined referring to the applied analytical method. In 2011, the International Standard ISO 11262 has been published which specifies a normative analytical method for the determination of total cyanide in soil. The objective of the project described in this paper was to provide the first soil reference material (CRM) certified for its mass fraction of total cyanide on the basis of this standard. A total of 12 German laboratories with proven experience in the determination of cyanides in environmental samples participated in the certification study. Measurement results were evaluated in full compliance with the requirements of ISO Guide 35. Taking into account the results of the inter-laboratory comparison as well as the outcome of the homogeneity and stability studies, a certified mass fraction of total cyanide of 21.1 mg/kg and an expanded uncertainty (k=2) of 1.3 mg/kg were assigned to the material. The reference material has been issued as CRM BAM-U114.
Reference nanomaterials
(2016)
This chapter reviews relevant aspects of the still less explored field of RNMs. In the first part, definition of RMs according to different metrological levels was presented as well as the general strategy on their development. In the second part, the importance of RNMs in material science and nanotoxicology is explained and considerations on the use of silica nano-objects as potential future reference material was discussed. Overall, several points should be highlighted from this chapter: Definition of a reference material depends on the level of standardization. Certified reference material represents the highest level of traceability. Different types of reference materials, standard materials and certified reference materials are available, as shown in Table 3.1. The preparation of nano-objects with well-defined mechanical properties is still an unsolved issue and thus needs further R&D activities. Nevertheless, amorphous silica seems to be a promising candidate for reaching this objective. Traceable properties of nanomaterials are still limited to few cases such as primary particle size and thickness measurements of very thin films. In general, developed RMs are monoparametric thus, only one characteristic of the nano-objects is reported. In nanotoxicology, the challenge is in the development of suitable RNM that bears similarities to the measurements made on the sample analysed.
This project aims to develop capacity to produce certified reference materials (CRMs) for environmental analysis by transferring know-how between the partners and combining their skills to focus on environmental CRM production. The production process includes good manufacturing practices for processing materials, method development, the validation and application of homogeneity, stability and characterisation tests, the calculation of individual uncertainties (between-unit inhomogeneity, long term stability, characterisation) and combination of uncertainties to determine overall uncertainty of the matrix reference materials. An inter laboratory comparison registered as a EURAMET project is set as the ultimate project outcome, confirming the partners’ capabilities in applying newly acquired skills.