Superconductivity in the new salt based on deuterated ET (d/sub 8/-ET)/sub 4/HgBr/sub 2/Hg/sub 2Br/sub 6/ under low pressures (0.3-0.5 KBAR)

Summary form only given. The deuteration of the, terminal ethylene groups in bis(ethylene dithio)tetrathiafulvalene (ET) and some modification in chemical synthesis result in a salt based on d/sub 8/-ET with bromine-mercurate anion HgBr/sub 2/Hg/sub 2/Br/sub 6/. This salt is not superconductor at ambient pressure and demonstrates various temperature resistance dependence for different crystals in the same batch. Under low pressure (0.3-0.5 kbar) all the crystals undergo the superconducting transitions with various temperatures of T/sub onset/ = 2.0 K; 3.0 K; 4.5 K. In the latter case the application of weak magnetic field (/spl tilde/1.5 kOe), perpendicular to the plane of crystals, sharply increases resistance below 4.0 K, thus confirming the superconducting nature of this transition. The comparison of properties of the title salt with those of the proton analog (ET)/sub 4/Hg/sub 2.89/Br/sub 8/ is carried out. The influence of lability of mercury on the properties of these salts is discussed.