MELTING OF LIF AND NACL TO 1-MBAR - SYSTEMATICS OF IONIC SOLIDS AT EXTREME CONDITIONS

We report the first diamond cell data for the melting curves of LIF an d NaCl up to 1 Mbar (100 GPa). The melting curve of NaCl is in agreeme nt with shock data and shows a break in slope at 290 kbar due to the B 1(NaCl)-B2(CsCl) transition. LiF remains B1 to the highest pressure, a nd molecular dynamic simulations predict that molten LIF retains a sim ple-cubic B1-like structure. A plot of the recent Mainz diamond anvil melting curves for MgO, LiF, KBr, KCI, CsI, and NaCl shows that at ver y high pressure all the melting curves have very similar slopes approa ching a value of order 1-2 K/kbar.