Temperature dependence of the density of molten germanium and silicon measured by a newly developed Archimedian technique

We have developed a technique to exclude the effect of surface tension on a sinker for density measurements by the Archimedian technique. The rod diameters were progressively varied as 2.0, 1.5, 1.0, 0.9, 0.5 and 0.3 mm, respectively. Silicon melt density was measured by three types of probes having diameters 2.0, 1.5 and 1.0 mm, and germanium melt density was measured by four types of probes having diameters 2.0, 0.9, 0.5 and 0.3 mm. Buoyancy measurements were made for each diameter and the density measured was extrapolated to a diameter zero. The real density values are determined as the d = 0 values. This technique was applied to a boron doped silicon melt using a temperature varying from 1683 to 1753 K and the germanium melt temperature varying from 1209 to 1633 K. The temperature coefficient of the density, the silicon melt doped with boron (5.0 x 10(19) atoms/cm(3)) is - 2.63 x 10(-4) g/cm(3) K around 1698 K using a boron nitride crucible. The temperature coefficient of the germanium melt is - 4.42 x 10(-4) g/cm(3) K. The density anomaly has been observed under 1698 K with high reproducibility for a silicon melt, but this phenomena has not been observed in a germanium melt. We propose the extrapolation technique for measuring the density of liquid whose surface tension is unknown. (C) 1999 Published by Elsevier Science B.V. All rights reserved.