The weak bond energy and large anisotropic domain wall energy induce many special characteristics of the domain nucleation, growth, and polarization switch in triglycine sulfate (TGS) and imidazolium perchlorate (IM), two typical molecular ferroelectrics. Their domain nucleation and polarization switch are rather slower than those of conventional oxide ferroelectrics, which may be due to the weaker bond energy of hydrogen bond or van der Waals bond than that of ionic bond. These chemical bonds dominate the elastic energy, with the latter being an important component of domain wall energy and playing an important role in domain nucleation and domain growth. The ratio of anisotropic domain wall energy to Gibbs free energy is large in TGS and IM, which allows a favorable domain shape and a special domain evolution under a certain electric field. Therefore, this study not only sheds light on the physical nature but also indicates the application direction for molecular ferroelectrics. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: The work is supported by the National Natural Science Foundation of China (11134004, 11234005, and 51472118), and a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions. J. W. acknowledges support from National Research Foundation of Singapore under project NRF-CRP5-2009-04. The authors also thank Prof. Ren-Gen Xiong from Southeast University, Nanjing, China for providing all ferroelectric crystals.