MELTING PRESSURE CURVES AND HIGH-TEMPERATURE SOLID-SOLID TRANSITIONS OF MERCURY II HALIDES UP TO 6 KBAR AND A NEW HIGHLY CONDUCTING POLYMORPH OF MERCURY II IODIDE.

Melting pressure curves and high-temperature solid-solid transition lines in the phase diagrams of mercury II halides have been determined in an internally heated pressure vessel up to 6 kbar containing argon as pressure transmitting medium. DTA signals and discontinuities in electrical conductance have been used for detecting the phase transitions. A new solid high-temperature high-pressure polymorph of HgI//2 was found, which has an electrical conductivity of about 2 OMEGA ** minus **1 cm** minus **1, about twice that of molten HgI//2//0 under the same pressure and temperature conditions. Refs.