New Developments in Diamond-Cell Research.

Abstract

Melting of the compressible alkali halides (KBr, KCl, CsI, NaCl, LiF) have been measured up to 1 Mbar. Their melting slopes approach values between 1 and 2 K/kbar at high pressures, a trend similar to almost all other materials measured thus far. Based on this trend and the close agreement in the melting temperatures between the diamond cell and shock wave experiments for the alkali halides and aluminum, and based on systematics in the magnitude of the change in sound velocity upon melting, we reinterpret the shock sound velocity measurements on iron as indicating onset of melting at 2 Mbar instead of 2. 4 Mbar as previously reported. This may reconcile the assumed discrepancies between static and shock experiments for iron. A new method for analyzing samples from laser heated diamond cells using an ion probe is presented. Chemical diffusion profiles were measured on samples with dimensions of order 10 μm by depth profiling with a radial resolution of about 2μm and a depth resolution of about 100 nm. We present first results on the partitioning and diffusion of nickel and cobalt in Mg-Si-perovskite at pressures up to 800 kbar and temperatures up to 2500 K.