Density measurements of liquids at high pressure: Modifications to the sink/float method by using composite spheres, and application to Fe-10wt%S

We describe a new modification of the sink/float method of determining the density of molten materials under high pressure, and apply it to liquid Fe-10wt%S. The modification is based on the use of composite spheres made of a dense, metallic core and a sapphire or ruby mantle. Composite spheres permit tailored densities for use in a variety of liquid compositions. The inert mantle also prevents chemical reaction with molten metallic samples. The pressure dependence of the density of liquid Fe-10wt%S at 1773 K, determined by bracketing, using composite spheres, is compared with the equation of state of Fe-10wt%S obtained by Sanloup et al. (2000), using X-ray absorption.