Phase transitions, optical, dielectric and viscoelastic properties of colloidal suspensions of BaTiO₃ nanoparticles and cyanobiphenyl liquid crystals

Abstract

We report experimental studies on the phase transitions and physical properties of colloidal suspensions of BaTiO₃ nanoparticles and two cyanobiphenyl liquid crystals (4-pentyl-4ʹ-cyanobiphenyl and 4-octyl-4ʹ-cyanobiphenyl). From the differential scanning calorimetric measurements, we show that the nanoparticles have antagonistic effect on the isotropic to nematic and nematic to smectic-A phase transitions. The birefringence, dielectric anisotropy and splay elastic constant remain almost unchanged, whereas the bend elastic constant and rotational viscosity decrease considerably. The experimental results are discussed based on the possible contribution of BaTiO₃ nanoparticles and free surfactant molecules in the suspensions.

Keywords:

• nanoparticles
• liquid crystals
• phase transitions
• viscoelastic properties

Acknowledgement

We acknowledge experimental support of Dr. S. Maqbool Ahmed, Principal Scientific Officer, CIL, UoH.

Additional information

Funding

We gratefully acknowledge the support from the UPE-II, DST(SR/NM/NS-134/2010), CSIR(03(1207)/12/EMR-II) and DST-PURSE. MVR acknowledges UGC-BSR for fellowship.