Anomalous Heat Capacity Associated with the Incommensurate SmA Phase in DB7OCN + 80CB

  • C. W. Garland
  • P. Das
Part of the NATO ASI Series book series (NSSB, volume 166)

Abstract

A high-sensitivity ac calorimeter has been used to determine the anomalous heat capacity associated with the SmAd-SmAic-SnA2 phase transitions in a smectic liquid crystal mixture of DB7OCN and 80CB. SmAd is a partial bilayer smectic A phase (L < d < 2L) and SmA2 is a bilayer smectic (d = 2L), where L is the molecular length. SmAic is an incommensurate smectic phase exhibiting the simultaneous presence of two collinear mass density modulations with periods whose ratio is not a rational fraction. In addition, heat capacity and x-ray data on pure DB7OCN indicate that the direct SmAd-SmA2 transformation in that material occurs continuously without undergoing a thermodynamic transition.

Keywords

Enthalpy Calorimeter Rounded 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. 1.
    B. R. Ratna, R. Shashidhar and V. N. Raja, Phys. Ref. Let. 55, 1476 (1985).ADSCrossRefGoogle Scholar
  2. 2.
    B. R. Ratna, R. Shashidhar and V. N. Raja, J. Phys. (Paris), in press.Google Scholar
  3. 3.
    The ac calorimeter experimental technique is described in C. W. Garland, Thermochim. Acta 88, 127 (1985).CrossRefGoogle Scholar
  4. 4.
    P. Barois, Phys. Rev. A33, 3632 (1986).ADSGoogle Scholar
  5. 5.
    R. Shashidhar, private communication.Google Scholar
  6. 6.
    C. W. Garland and P. Das (to be published).Google Scholar
  7. 7.
    K. Chan, P. S. Pershan, L. B. Sorensen and F. Hardouin, Phys. Rev. (in press).Google Scholar
  8. 8.
    P. Barois, J. Prost and T. C. Lubensky, J. Phys. (Paris) 46, 391 (1985).CrossRefGoogle Scholar
  9. 9.
    P. Das, C. W. Garland, R. Shashidhar (to be published).Google Scholar

Copyright information

© Plenum Press, New York 1987

Authors and Affiliations

  • C. W. Garland
    • 1
  • P. Das
    • 1
  1. 1.Department of Chemistry and Center for Materials Science and EngineeringMassachusetts Institute of TechnologyCambridgeUSA

Personalised recommendations