Critical linear thermal expansion in the smectic-Aphase near the nematic-smectic phase transition
| Autor: | Emily P. Anesta, Carl W. Garland, Germano S. Iannacchione |
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| Rok vydání: | 2004 |
| Předmět: | |
| Zdroj: | Physical Review E. 70 |
| ISSN: | 1550-2376 1539-3755 |
| DOI: | 10.1103/physreve.70.041703 |
| Popis: | Recent high-resolution x-ray investigations of the smectic-$A$ (SmA) phase near the nematic-to-SmA transition provide information about the critical behavior of the linear thermal expansion coefficient ${\ensuremath{\alpha}}_{\ensuremath{\Vert}}$ parallel to the director. Combining such data with available volume thermal expansion ${\ensuremath{\alpha}}_{V}$ data yields the in-plane linear expansion coefficient ${\ensuremath{\alpha}}_{\ensuremath{\perp}}$. The critical behaviors of ${\ensuremath{\alpha}}_{\ensuremath{\Vert}}$ and ${\ensuremath{\alpha}}_{\ensuremath{\perp}}$ are the same as those for ${\ensuremath{\alpha}}_{V}$ and the heat capacity ${C}_{p}$. However, for any given liquid crystal, ${\ensuremath{\alpha}}_{\ensuremath{\Vert}}(\mathrm{crit})$ and ${\ensuremath{\alpha}}_{\ensuremath{\perp}}(\mathrm{crit})$ differ in sign. Furthermore, the quantity ${\ensuremath{\alpha}}_{\ensuremath{\Vert}}(\mathrm{crit})$ is positive for ${\mathrm{SmA}}_{d}$ partial bilayer smectics, while it is negative for nonpolar ${\mathrm{SmA}}_{m}$ monomeric smectics. This feature is discussed in terms of the molecular structural aspects of these smectic phases. |
| Databáze: | OpenAIRE |
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