MERCURY SELENIDE STOICHIOMETRY AND PHASE-RELATIONS IN THE MERCURY SELENIUM SYSTEM

The phase relations in the 0-65 at% Hg portion of the condensed mercury-selenium system were determined from liquidus temperatures to 250 degree C by evacuated silica tube experiments in which vapor is always a phase. Stoichiometric HgSe melts at 795 plus or minus 2 degree C whereas Hg//0//. //5//1Se//0//. //4//9 melts at 797 plus or minus 2 degree C and Hg//0//. //4//9Se//0//. //5//1 melts at 793 plus or minus 2 degree C. In the HgSe-Se portion of the system a monotectic exists at 683 plus or minus 3 degree C and 71. 5 at% Se and a liquid immiscibility field at this temperature extends from 71. 5 to 85. 5 at% Se. The presence of HgSe depresses the melting temperature of Se by about 8 degree C. An eutectic exists between HgSe and Se at 208 degree C and a composition of more than 99. 95 at% Se. In the Hg-HgSe portion of the system a monotectic exists at 708 plus or minus 3 degree C and about 25 at% Se.