Infrared Study of the Structural Phase Transition in a Ternary ID Salt (TMA+)(TCNQ)2/3− (13−)1/3

Graja, A.; Sopa, E.; Dobiášová, L.

doi:10.1002/pssa.2210730263

Cited by 5 publications

(1 citation statement)

References 9 publications

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“…3-6. and is still visible at room temperature. This behaviour resembles that observed for the higherfrequency a, modes in the mid-infrared ( 1 I , 12,26,27). Figure 4 shows the unexpected temperature dependence of the 126 cm-' mode which starts to grow strongly only below 100 K. This corresponds to the growth of the second distortion which precedes the phase transition at 89 K. The mode could, therefore, be a torsion of the methyl groups if their rotation is indeed frozen out at this temperature, or it may be one for which the intensity depends strongly on the angle of tilt of the TCNQ molecules.…”

Section: Resultssupporting

confidence: 75%

Far-infrared powder spectrum of (N(CH₃)₃D)(I)(TCNQ)

Eldridge¹,

Fortier²,

Bates³

et al. 1983

Can. J. Phys.

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We present the powder absorption spectrum of (TMA)(I)(TCNQ) in the far-infrared as a function of temperature. Below 160 K new absorption features appear and others increase in intensity. This behaviour supports the electron-and neutrondiffraction evidence of a distortion on the TCNQ chains below the first phase-transition temperature. Effects due to the second phase transition at 89 K are also observed. The results of a group-theoretical analysis are presented. These show that totally-symmetric internal modes n, are to be expected in the infrared spectra of this compound even in the undistorted phase.Nous prksentons le spectre d'absorption de poudre de (TMA) (I) (TCNQ) dans I'infrarouge lointain, en fonction de la tempkrature. Au dessous de 160 K , de nouvelles frkquences d'absorption apparaissent et d'autres augmentent d'intensitt. Ce comportement confirme les indications de la diffraction des neutrons et des klectroni sur I'existence d'une distorsion des chaines TCNQ au-dessous de la premikre temptrature dc transition de phase. On observe aussi des effets dus a la seconde transition de phase a 89 K. Les rtsultats d'une analyse par thkorie des groupes sont prtsentks. Ils montrent que des modes internes totalement symktriques (a,) doivent itre attendus dans le spectre infrarouge de ce compost, mime dans la phase sans distorsion.[Traduit par le journal]Can.

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Section: Resultssupporting

confidence: 75%

Far-infrared powder spectrum of (N(CH₃)₃D)(I)(TCNQ)

Eldridge¹,

Fortier²,

Bates³

et al. 1983

Can. J. Phys.

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Mircowave conductivity and thermoelectric power of some ternary salts of TCNQ and iodine

S̀wietlik

Mihály

Delhaès

1988

Phys. Stat. Sol. (a)

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For a series of ternary compounds made with TCNQ, iodine, and quaternary ammonium the complex dielectric constant a t microwave frequency (9.1 GHz) and the thermoelectric power are measured in the temperature range 80 t o 300 I ( . Above a "Peierls-like" transition the thermoelectric power results are discussed in terms of a n intrinsic semiconductor with Hubbard gap. For interpretation of the microwave results in the high-temperature phase a n interrupted strand model can be applied, whereas in the low-temperature phase the localized electron concept i s important.Pour une sBrie des sels ternaires compos6s d u TCNQ, d'iode e t d'ammonium quaternaire, on a ktudiB. en fonction de la temperature (SO Q. 300 K), le pouvoir thermo8lectrique et la constante dielectrique B une frhquence microonde (9,l GHz). On a associS: le comportement du pouvoir thermohlectrique au-dessus de la transition de "type de Peierls" B celui d'un semiconducteur present. a n t u n gap de Hubbard. Pour interpreter les resultats microondes d a m la phase haute-temperature on peut appliquer le modele, de segments coup6s alors que d a m la phase basse-temperature I'influence de la localization des Blectrons peut atre importante. R. SWIETLIK, G. MIHALY, and 9. SELHA~S

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