Metal-insulator transition of alloyed radical cation salts, (Me sub(xEDO-TTF)) sub(2)PF sub(6)

• Published in: Physica. B, Condensed matter Condensed matter, 2010-06, Vol.405 (11), p.S45-S48
• Main Authors: Murata, Tsuyoshi, Shao, Xiangfeng, Nakano, Yoshiaki, Yamochi, Hideki, Saito, Gunzi, Uruichi, Mikio, Yakushi, Kyuya, Tanaka, Koichiro
• Format: Article
• Language: English
• Subjects: Alloys; Cations; Condensed matter; Crystal structure; Derivatives; Metal-insulator transition; Radicals; Stacking
• ISSN: 0921-4526
• DOI: 10.1016/j.physb.2009.12.042

Ternary radical cation salts containing ethylenedioxytetrathiafulvalene, its mono-methyl substituted derivative, and hexafluorophosphate, [(EDO-TTF) sub(1-) sub(x)(MeEDO-TTF) sub(x]) sub(2)PF sub(6 (x=mole fraction of MeEDO-TTF, x=0.01-0.13) were prepared by electrooxidation. Mole fractions of EDO-TTF and MeEDO-TTF in EDO-TTF rich alloys were consistent with the donor mixing ratios in preparation. Crystal structures of these alloys at room temperature were isostructural to that of (EDO-TTF)) sub(2)PF sub(6, where the donor molecules formed a nearly uniform stacking column to give a quasi-one-dimensional Fermi surface. The alloys exhibited a metal-insulator transition with tetramerization within the donor stack and anion-ordering. Temperature-variable structural analysis and Raman spectra revealed that the charge-ordering took place in the low temperature phase of x=0.05 alloy, however, this feature vanished in the x=0.13 alloy. The phase transition temperature decreased with increasing x value from 279 K of pristine (EDO-TTF)) sub(2)PF sub(6 to 188 K of x=0.13 alloy.)