Abstract
The x-ray diffuse scattering study of the highly conducting form () of N-methylphenazinium-tetracyanoquinodimethanide [(NMP)(TCNQ)] shows that the methyl groups, although less ordered than in the less highly conducting form (), still display substantial local order of the same type along the stacking direction. In addition, it shows two types of one-dimensional (1-D) scattering bearing resemblance to the Kohn anomalies earlier observed in (TTF)(TCNQ). A first 1-D scattering is observed at room temperature at the wave vector ; it couples three-dimensionally below approximately 200 K. Further diffuse scattering is observed below 70 K at half the previous wave vector (). As expected in an intrinsically disordered system (as potassium cyanoplatinate [Pt·3O (KCP)] no long-range 3-D ordering is observed down to 20 K. Our results cannot ascribe unambiguously the and a scattering to and anomalies (as was done for tetrathiafulvalenium-tetracyano--quinodimenthanide [(TTF)(TCNQ)], but strongly suggests that the charge transfer in (NMP)(TCNQ) is electron, and is quite far from unity as previously deduced from other work. Temperature-dependent dc conductivity measurements after x-ray study unequivalocally associate the highly conducting form with these properties.
- Received 29 March 1979
DOI:https://doi.org/10.1103/PhysRevB.21.486
©1980 American Physical Society