Enhancement of dielectric and electro-optical parameters of a newly prepared ferroelectric liquid crystal mixture by dispersing nano-sized copper oxide

ABSTRACT

Here, we present the effect of copper (II) oxide nanoparticles (nCuO) on dielectric and electro-optical parameters of a newly prepared ferroelectric liquid crystal (FLC) mixture, namely W302. The FLC mixture, comprising of pyrimidine compounds, was characterised through dielectric spectroscopy, differential scanning calorimetry (DSC), polarising optical microscopy (POM) and other electro-optical methods. The material parameters such as spontaneous polarisation, rotational viscosity, response time and tilt angle of W302 were found to be 14 nC/cm², 240 mPa.s, 150 µs and 28^ᴼ, respectively. The phase transition temperatures of W302 were observed through DSC and further confirmed by the dependence of dielectric loss factor in homogeneously aligned FLC sample with temperature. We also demonstrate the observance of a low-frequency dielectric relaxation mode due to the unwinding of the helix, called as partially unwound helical mode (p-UHM) along with Goldstone mode. The behaviour of p-UHM has been systematically studied with temperature and applied bias field. Further, dispersion of nCuO into host W302 has shown a significant increase in dielectric permittivity. Also, the p-UHM relaxation peak in the dielectric regime has disappeared with the incorporation of nCuO. These studies would be useful to fabricate better electro-optical devices for display, switching and beam steering applications. The formulation and characterization of a ferroelectric liquid crystal (FLC) mixture W302 composed of pyrimidine compounds is presented. Then, we observed the effect of copper (II) oxide nanoparticles (nCuO) on dielectric and electro-optical parameters of a newly prepared and characterized FLC mixture.

Graphical Abstract

KEYWORDS:

• Dielectric
• electro-optical
• p-UHM
• FLC mixture
• W302
• nCuO

Acknowledgments

The authors sincerely thank Director, CSIR-CEERI, Pilani and CSIR-NPL, New Delhi for continuous encouragement and interest in this work. A part of this work, connected with development of pure FLC mixture, was supported by the Polish Ministry of Science and Higher Education the Statutory Activity PBS-651 of Military University of Technology.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The author (J.P.) is grateful to the Council of Scientific and Industrial Research, New Delhi, India for supporting this work through Extra Mural Research Project (Project No. 03(1395)/17/EMR-II). One of the authors (AMB) is thankful to the DST and CSIR –New Delhi for providing the financial assistance.