Flotation measurements to reveal the reason for the discrepancy in the molar volume of silicon

To reveal the reason for the discrepancy of relatively 3·10^-6 in the molar volume of silicon found in crystals of different origin, the densities of crystals grown under different conditions were compared using a flotation method. The method and the apparatus used at Physikalisch-Technische Bundesanstalt, Braunschweig, Germany, and the evaluation of data using Lagrange multipliers are described. The obtained results are reported and the contributions to the standard uncertainty of the silicon density ρ_si of about 1.0·10^-7ρ_si are discussed.