Characterization of the Electrocrystallization Products of Bis(ethylenedithio)tetraselenafulvalene (BETS) and Tetrabutylammonium Tetrachlorogallate

Nine different crystal morphologies have been isolated from the electrocrystallization products of bis(ethylenedithio)tetraselenafulvalene (BETS) and tetrabutylammonium tetrachlorogallate. The morphologies have been examined by X-ray crystallography and electrical transport measurements and have been assigned to several different crystal systems: κ-, λ-, and κ′-(BETS)2GaCl4, α-(BETS)3GaCl4-TCE, and an incompletely characterized semiconductor. In experiments designed to gain some understanding of the variable resistive superconducting transition temperatures (Tc) in λ-(BETS)2GaCl4, the influence of gold paste on the AC susceptibility TC was examined: gold paste raises the onset of superconductivity, and the effect is reversible. In related studies, it was found that isotropic pressure lowers Tc in λ-(BETS)2GaCl4 by-0.31 K/kbar. These observations are discussed.