X-RAY STRUCTURE OF CS-DOPED POLYACETYLENE

The x-ray powder profile of heavily doped [(CH)Csy]x is analyzed on the basis of three dimensionally ordered intercalate channels. Fifteen peaks representing 27 unique reflections are well described (positions and intensities) by a tetragonal pseudocell with Ä=b»=9.093 AI, c»=7.950 AI containing 24 (CH) and 4 Cs units (y=0.167). The Cs and (CH) sublattices are actually incommensurate along c», with 6.46 undistorted (CH) units per Cs implying y=0.15. Reflections with nonzero L are significantly less intense than calculated neglecting the Debye-Waller factor, indicating large-amplitude c-axis thermal motion of Cs ions. The fractional linear in-plane dilation upon replacing K with Cs is within 20% of the corresponding value in graphite intercalates. © 1990 The American Physical Society.