The isotopic composition of the new enriched silicon crystal Si28-31Pr11: Maintaining the realization and dissemination of the mole and the kilogram via the XRCD method

IF 2.1 3区工程技术 Q2 INSTRUMENTS & INSTRUMENTATION

Metrologia Pub Date : 2024-01-25 DOI:10.1088/1681-7575/ad2272

A. Pramann, O. Rienitz

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Abstract

The molar mass and isotopic composition of a new silicon single crystal material (Si28-31Pr11) highly enriched in 28Si has been determined in the context of the X-ray crystal density (XRCD) method used for the realization and dissemination of the SI base units ‒ the mole and the kilogram. Isotope ratio measurements have been performed using a high-resolution multicollector-inductively coupled plasma mass spectrometer (MC-ICP-MS) with improved technical performance. By applying the Virtual-Element Isotope Dilution Mass Spectrometry (VE-IDMS) method, different crystal areas enclosing the locations of two silicon spheres have been investigated with respect to the magnitude of tentative variations in the molar mass and isotopic composition of the respective samples as a function of their original location in the crystal ingot. In total, 18 subsamples from four different axial and several related radial posi-tions have been characterized. An average molar mass M(Si28-31Pr11) = 27.976 941 464(41) g mol-1 corresponding to a relative combined uncertainty u c,rel(M(Si28-31Pr11)) = 1.4 × 10-9 was yielded. The average enrichment in 28Si of the crystal is expressed by the mean amount-of-substance fraction x(28Si) = 0.999 985 350(37) mol/mol. Two spheres were cut from the crystal ingot. The average molar masses of the spheres Si28kg_03_a and Si28kg_03_b are: M(Si28kg_03_a) = 27.976 941 467(43) g mol-1 and M(Si28kg_03_b) = 27.976 941 461(44) g mol-1, respectively. The results are discussed using uncertainty budgets according to the Guide to the expression of uncertainty in measurement (GUM). A homogeneous distribution of the molar mass throughout the crystal is suggested, qualifying it as a material for a primary stand-ard – a silicon sphere – for the realization and dissemination of the mole and the kilogram. A comparison with enriched silicon crystals that are already available is given.

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新富硅晶体 Si28-31Pr11 的同位素组成：通过 XRCD 方法保持摩尔和千克的实现和传播

一种新型硅单晶材料（Si28-31Pr11）的摩尔质量和同位素组成高度富含 28Si，该材料是在 X 射线晶体密度（XRCD）方法的背景下测定的，XRCD 方法用于实现和推广国际单位制基本单位--摩尔和千克。同位素比值测量是利用技术性能更高的高分辨率多收集器-电感耦合等离子体质谱仪（MC-ICP-MS）进行的。通过应用虚拟元素同位素稀释质谱法（VE-IDMS），研究了两个硅球所在位置所包围的不同晶体区域，以及各自样品的摩尔质量和同位素组成的暂定变化幅度与晶体锭中原始位置的函数关系。总共对来自四个不同轴向位置和几个相关径向位置的 18 个子样品进行了表征。平均摩尔质量 M(Si28-31Pr11) = 27.976 941 464(41) g mol-1，相对综合不确定度 u c,rel(M(Si28-31Pr11)) = 1.4 × 10-9。晶体中 28Si 的平均富集度用平均物质的量分数 x(28Si) = 0.999 985 350(37) mol/mol 表示。从晶体锭中切割出两个球体。球体 Si28kg_03_a 和 Si28kg_03_b 的平均摩尔质量分别为M(Si28kg_03_a) = 27.976 941 467(43) g mol-1 和 M(Si28kg_03_b) = 27.976 941 461(44) g mol-1。根据测量不确定度表达指南 (GUM)，使用不确定度预算对结果进行了讨论。结果表明，整个晶体的摩尔质量分布均匀，可以作为实现和传播摩尔和千克的主要标准（硅球）材料。与现有的富硅晶体进行了比较。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Metrologia 工程技术-物理：应用

CiteScore

2.80

自引率

25.00%

发文量

137

审稿时长

12 months

期刊介绍： Published 6 times per year, Metrologia covers the fundamentals of measurements, particularly those dealing with the seven base units of the International System of Units (metre, kilogram, second, ampere, kelvin, candela, mole) or proposals to replace them. The journal also publishes papers that contribute to the solution of difficult measurement problems and improve the accuracy of derived units and constants that are of fundamental importance to physics. In addition to regular papers, the journal publishes review articles, issues devoted to single topics of timely interest and occasional conference proceedings. Letters to the Editor and Short Communications (generally three pages or less) are also considered.