| Autor: |
Noel A. Clark, C. D. Muzny, Larry Hrubesh, Aaron G. Rappaport, Britt N. Thomas, Tommaso Bellini, R. Malzbender, Dale W. Schaefer |
| Rok vydání: |
1993 |
| Předmět: |
|
| Zdroj: |
Physical review letters. 71(21) |
| ISSN: |
1079-7114 |
| Popis: |
We have studied, via x-ray scattering, the nematic to smectic-A (NA) translational ordering of the liquid-crystal--forming compound octylcyanobiphenyl (8CB) incorporated into the pores of a silica aerogel. We find that the aerogel dramatically alters 8CB phase behavior, eliminating the NA transition found at T=${\mathit{T}}_{\mathit{N}\mathit{A}}$=33.7 \ifmmode^\circ\else\textdegree\fi{}C in bulk samples and replacing it by a short range smectic ordering having a correlation length which at ${\mathit{T}}_{\mathit{N}\mathit{A}}$ is \ensuremath{\xi}\ensuremath{\sim}40 \AA{}, much smaller than the aerogel pore and nematic domain size ${\ensuremath{\xi}}_{\mathit{p}}$\ensuremath{\sim}200 \AA{}. As T is lowered this smectic disorder is eliminated from the pores, \ensuremath{\xi} increasing continuously over a 20 \ifmmode^\circ\else\textdegree\fi{}C range to saturate at ${\ensuremath{\xi}}_{\mathit{p}}$ for T${\mathit{T}}_{\mathit{N}\mathit{A}}$-20 \ifmmode^\circ\else\textdegree\fi{}C. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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