CHARACTERIZATION OF THE ELECTROCRYSTALLIZATION PRODUCTS OF BIS(ETHYLENEDITHIO)TETRASELENEFULVALENE (BETS) AND TETRABUTYLAMMONIUM TETRACHLOROGALLATE

Nine different crystal morphologies have been isolated from the electr ocrystallization products of bis(ethylenedithio)tetraselenafulvalene ( BETS) and tetrabutylammonium tetrachlorogallate. The morphologies have been examined by X-ray crystallography and electrical transport measu rements and have been assigned to several different crystal systems: k appa-, lambda-, and kappa'-(BETS)2GaCl(4), alpha-(BETS)(3)GaCl4 . TCE, and an incompletely characterized semiconductor. In experiments desig ned to gain some understanding of the variable resistive superconducti ng transition temperatures (T-c) in lambda-(BETS)(2)GaCl4, the influen ce of gold paste on the AC susceptibility T-c was examined: gold paste raises the onset of superconductivity, and the effect is reversible. In related studies, it was found that isotropic pressure lowers T-c in lambda-(BETS)(2)GaCl4 by -0.31 K/kbar. These observations are discuss ed.