Measurement of the Sound Velocity behind a Shock-Wave Front in Mixtures of Iron with Diamond

摘要

The side rarefaction method was used to measure the sound velocities in pressed samples of 90/10 iron/diamond,85/15 iron/diamond,and 90/10 iron/sulfur mixtures and in samples of pressed iron (without additives) and St.3 steel.The measurement data were compared to geophysical data with a view to find a light chemical element (or elements) in the Earth's core composition that would reduce the total density of the core compared to an iron-nickel mixture without considerably reducing the sound velocity in the core compared to a pure iron-nickel mixture at the pressures occurring in the core.It was established that the addition of diamond results in an increase in the sound velocity in shock-compressed samples and a decrease in their density compared to the other samples;therefore,in simulations of the composition of the Earth's inner layers,it is necessary take into account the possible effect of carbon in the diamond phase.