Confirmation of the INRiM and PTB Determinations of the Si Lattice Parameter

Líu, Hao; Macfarlane, J.C.; Gallop, John; Cox, D. L.; Joseph-Franks, Patrick; Hutson, David; Chen, J.; Lam, Siu Shu Eddie

doi:10.1109/tim.2007.890618

Cited by 26 publications

(14 citation statements)

References 13 publications

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“…In the 1980s, using the x-ray interferometer, Becker et al [7] reported a reliable value of the Si crystal lattice constant with a relative standard uncertainty of 6.2 × 10 −8 . This value is still consistent with updated values for Si crystals with natural isotopic compositions [8].…”

Section: Introductionsupporting

confidence: 88%

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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Section: Introductionsupporting

confidence: 88%

Realization of the kilogram by the XRCD method

Fujii¹,

et al. 2016

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“…Because of anomalies in comparisons with national prototypes, a new definition of the unit of mass based on an invariant natural quantity has been taken into consideration [1]. One promising option is a precise determination of Avogadro's constant N A , for which the molar mass M Si [2] and the lattice plane spacing d 220 [3] of a silicon single crystal, and the mass m sphere [4] and the volume V sphere [5,6] of a sphere of the same crystal have to be determined with a relative uncertainty at a level of 10 −8 . Therefore, with the world's best possible polishing technique [7] performed by CSIRO, Australia, two spheres were produced from a unique crystal of highly enriched 28 Si [8].…”

Section: Introductionmentioning

confidence: 99%

Influence of the distribution of measuring points on the mean diameter determination of the Avogadro project's silicon spheres

Bartl¹,

Nicolaus²

2009

Meas. Sci. Technol.

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The members of the International Avogadro Project are aiming at the redetermination of Avogadro's constant with a relative uncertainty of less than 2×10−8 in order to be qualified for the redefinition of the kilogram. Therefore, among other quantities, the volume of a sphere made of a silicon single crystal has to be determined very precisely with a diameter uncertainty of 0.3 nm. A special Fizeau interferometer with spherical reference faces has been developed at PTB providing the required precision in absolute interferometry and a generous coverage of the surface of the sphere at the same time. Due to the intrinsic imbalanced distribution of measurement positions given by the setup, an equalization has to be performed without introducing a numerical error. In this paper an appropriate procedure using point distributions on a sphere is described and characterized with regard to the number of points involved.

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“…c. * ͒ ofBecker et al ͑2007͒ in Eq. ͑300͒ agrees with the 1994 INRIM result of Basile et al ͑1994͒, which was used as an input datum in the 1998 adjustment, because of the many advances incorporated in the new work, we no longer consider the old result.In addition to the determination described in the previous section of the…”

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confidence: 99%

CODATA recommended values of the fundamental physical constants: 2014

2016

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This paper gives the 2006 self-consistent set of values of the basic constants and conversion factors of physics and chemistry recommended by the Committee on Data for Science and Technology ͑CODATA͒ for international use. Further, it describes in detail the adjustment of the values of the constants, including the selection of the final set of input data based on the results of least-squares analyses. The 2006 adjustment takes into account the data considered in the 2002 adjustment as well as the data that became available between 31 December 2002, the closing date of that adjustment, and 31 December 2006, the closing date of the new adjustment. The new data have led to a significant reduction in the uncertainties of many recommended values.

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Confirmation of the INRiM and PTB Determinations of the Si Lattice Parameter

Cited by 26 publications

References 13 publications

Realization of the kilogram by the XRCD method

Realization of the kilogram by the XRCD method

Influence of the distribution of measuring points on the mean diameter determination of the Avogadro project's silicon spheres

CODATA recommended values of the fundamental physical constants: 2014

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