New Melting Law at High Pressures

Abstract

Published melting-temperature and compressibility data support the observation that for many substances, and for wide variations in pressure, the relation describing the change of melting temperature with pressure becomes linear when melting temperature is plotted against isothermal volume compression. Linear variation of melting temperature with compression holds for density changes of a factor of 2 in the alkali metals and in sodium chloride. If we assume that iron also exhibits a linear variation of melting temperature with compression for equally large compressions, then this fixes the earth's inner—outer-core boundary temperature at approximately 3724°C, provided that the boundary corresponds to the melting point of iron at a pressure of 3 Mbars.