Toward the Avogadro constant-preliminary results on the molar volume of silicon

Abstract

The silicon molar volume has been measured through atomic weight and density measurements. Mass spectrometric determination of the isotopic composition was performed on two differently grown samples by comparison with the US National Bureau of Standards (NBS) reference material SRM 990. The density of specimens from the same crystals was obtained through direct mass and dimension measurements on one single-crystal sphere and through hydrostatic comparison for another sphere. Compatibility with previous measurements was checked through hydrostatic comparison with IMGC Zerodur density standards. The two molar volume determinations differ by 0.14 p.p.m. The preliminary value obtained is 12.058, 843+or-0.000, 029 cm/sup 3//mol at 22.5 degrees C and in vacuo.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>