Multidisciplinary Materials Research Center, Frontier Institute of Science and Technology, Xi'an Jiaotong University, Xi'an 710049, China.
Published: July 2021
AI Article Synopsis
Article Abstract
Advanced ferroelectrics with a combination of large dielectric response and good temperature stability are crucial for many technologically important electronic devices and electrical storage/power equipment. However, the two key factors usually do not go hand in hand, and achieving high permittivity is normally at the expense of sacrificing temperature stability. This trade-off relation is eased but not fundamentally remedied using relaxor-type materials which are known to have a diffuse permittivity peak at their relaxor transition temperatures. Here, we report an anomalous trirelaxor phenomenon in a barium titanate system and show that it can lead to a giant dielectric permittivity (ε ≈ 18 000) over a wide temperature range ( ≈ 34K), which successfully overcomes a long-standing permittivity-stability trade-off. Moreover, the enhancement in the dielectric properties also yields a desired temperature-insensitive electrocaloric performance for the trirelaxor ferroelectrics. Microstructure characterization and phase-field simulations reveal a mixture of tetragonal, orthorhombic, and rhombohedral polar nanoregions over a broad temperature window in trirelaxor ferroelectrics, which is responsible for this combination of giant dielectric permittivity and good temperature stability. This finding provides an effective approach in designing advanced ferroelectrics with high performance and thermal stability.
Dielectric metasurfaces open new avenues in nonlinear optics through their remarkable capability of boosting frequency conversion efficiency of nonlinear optical interactions. Here, a metasurface consisting of a square array of cruciform-shaped silicon building blocks covered by a monolayer MoS is proposed. By designing the metasurface so that it supports optical bound states in the continuum (BICs) at the fundamental frequency and second harmonic, nearly 600× enhancement of the second-harmonic generation (SHG) in the MoS monolayer as compared to that of the same MoS monolayer suspended in air is achieved.
Bound state in the continuum (BIC) has been considered a promising strategy to reduce fabrication complexity and radiative loss. Despite the successful demonstration of many BIC-based configurations, their mode confinement is comparable to conventional dielectric waveguides. Even though plasmonics with strong light localization have been introduced into BICs, the intrinsic ohmic loss is still a facing challenge to be conquered.
Ferroelectric nematic liquid crystals (NFLCs) are promising electronic materials owing to their giant permittivity, polarization, and nonlinear optical coefficients. Although it is difficult to polymer-stabilize the NFLC orientation state due to their low affinity to polymers, in this study, we have succeeded in stabilizing the orientation into a blue phase (BP) three-dimensional structure by using BP polymer networks. This BP polymer-templated NFLC retains their ferroelectric properties and stabilizes with macroscopically canceled polarization due to the BP structure.
Centre for OptoElectronics and Biophotonics (COEB), School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798.
Förster resonance energy transfer (FRET), driven by dipole-dipole interactions (DDIs), is widely utilized in chemistry, biology, and nanophotonics. However, conventional FRET is ineffective at donor-acceptor distances exceeding 10 nm and measurements suffer from low signal-to-noise ratios. In this study, we demonstrate significant FRET enhancement and extended interaction distances under ambient conditions by utilizing a bound state in the continuum (BIC) mode within a dielectric metasurface cavity.
National Engineering Research Center of Novel Equipment for Polymer Processing, Key Laboratory of Polymer Processing Engineering, Ministry of Education, Guangdong Provincial Key Laboratory of Technique and Equipment for Macromolecular Advanced Manufacturing, Department of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou, 510641, China.
Domains play an essential role in determining the piezoelectric properties of polymers. The conventional method for achieving ultrafine piezoelectric domain structures for polymers is multiphase polymerization, which is not the primary choice for industrial-scale applications because of its complex synthesis and weak mechanical properties. In this study, it is demonstrated for the first time that a nanoscale domain design can be achieved in a commercially available polyvinylidene fluoride (PVDF) homopolymer through a simple fabrication method involving cyclic compression and rapid freezing.
