Diameter comparison of a silicon sphere for the International Avogadro Coordination project

Kuramoto, Noriyuki; Fujii, K.; Nicolaus, Arnold; Bartl, Guido; Gray, Malcolm B.; Manson, P. J.; Giardini, W.

doi:10.1109/cpem.2010.5544274

Cited by 4 publications

(3 citation statements)

References 27 publications

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“…Between each set of measurements, the sphere was rotated to distribute 7782 (=2594×3) points as uniformly as possible. Before each set of measurements, the spheres were washed using the same procedure used for the international comparisons of the mass and diameter of a Si sphere in the International Avogadro Coordination project [38,41]. The standard deviation of the mean OL thickness for 3 sets of the measurements was less than 0.1 nm, showing the uniformity of the distribution of the 2594 points and the reliability of the measurement system.…”

Section: Surfacementioning

confidence: 99%

Improved measurement results for the Avogadro constant using a²⁸Si-enriched crystal

Azuma¹,

et al. 2015

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New results are reported from an ongoing international research effort to accurately determine the Avogadro constant by counting the atoms in an isotopically enriched silicon crystal. The surfaces of two 28 Si-enriched spheres were decontaminated and reworked in order to produce an outer surface without metal contamination and improved sphericity. New measurements were then made on these two reconditioned spheres using improved methods and apparatuses. When combined with other recently refined parameter measurements, the Avogadro constant derived from these new results has a value of N A = 6.022 140 76(12) × 10 23 mol -1 . The X-ray crystal density method has thus achieved the target relative standard uncertainty of 2.0 × 10 -8 necessary for the realization of the definition of the new kilogram.

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Section: Surfacementioning

confidence: 99%

Improved measurement results for the Avogadro constant using a²⁸Si-enriched crystal

Azuma¹,

et al. 2015

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“…The NMIJ‐S4 and NMIJ‐S5 Si spheres were manufactured by the Commonwealth Scientific and Industrial Research Organisation (CSIRO, Australia) . Before XPS measurements, the spheres were cleaned by manual washing with DeconexTM solution followed by rinsing with ultrapure water and finally rinsing with ethanol …”

Section: Methodsmentioning

confidence: 99%

XPS study of silicon spheres as a density standard

Zhang

Kuramoto

Kurokawa

et al. 2018

Surface & Interface Analysis

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As density is one of the basic physical properties of materials, an accurate density standard is absolutely essential. To determine density with high accuracy and precision, two 1‐kg single‐crystal silicon spheres (NMIJ‐S4 and NMIJ‐S5) are used as the primary standard at the National Metrology Institute of Japan. For the accurate measurement of the mass and volume of the silicon spheres, the effects of the surface layer must be carefully considered. In this work, a surface layer model of NMIJ‐S4 and NMIJ‐S5 was proposed and the thicknesses of each surface layer were determined using X‐ray photoelectron spectroscopy. A detailed uncertainty budget is presented to aid use of the density standard.

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“…Several NMIs have developed interferometers to measure the sphere volume [69], in which the diameter is measured in many different directions. The volume is calculated from the measured mean diameter with high accuracy when the deviation from a perfect spherical shape is small.…”

Section: Diameter and Volume Measurementsmentioning

confidence: 99%

Realization of the kilogram by the XRCD method

Fujii¹,

et al. 2016

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When the kilogram is redefined in terms of the fixed numerical value of the Planck constant h, the x-ray-crystal-density (XRCD) method, among others, is used for realizing the redefined kilogram. The XRCD method has been used for the determination of the Avogadro constant N A by counting the number of atoms in a 28 Si-enriched crystal, contributing to a substantial reduction of uncertainty in the values of N A and h to 2 parts in 10 8 . This method can be therefore used reversely for the mass determination of a 1 kg sphere prepared from the crystal. This is realized by SI-traceable measurements of its lattice parameter, isotopic composition, volume, and surface properties. Details of the corresponding measurements are provided, as well as the concept of the XRCD method, isotope enrichment, crystal production, sphere manufacturing, and evaluation of impurities and self-point defects in the crystal, together with mass comparison with respect to the silicon sphere for disseminating mass standards.

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Diameter comparison of a silicon sphere for the International Avogadro Coordination project

Cited by 4 publications

References 27 publications

Improved measurement results for the Avogadro constant using a²⁸Si-enriched crystal

Improved measurement results for the Avogadro constant using a²⁸Si-enriched crystal

XPS study of silicon spheres as a density standard

Realization of the kilogram by the XRCD method

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Diameter comparison of a silicon sphere for the International Avogadro Coordination project

Cited by 4 publications

References 27 publications

Improved measurement results for the Avogadro constant using a28Si-enriched crystal

Improved measurement results for the Avogadro constant using a28Si-enriched crystal

XPS study of silicon spheres as a density standard

Realization of the kilogram by the XRCD method

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Product

Resources

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Improved measurement results for the Avogadro constant using a²⁸Si-enriched crystal

Improved measurement results for the Avogadro constant using a²⁸Si-enriched crystal