Showing papers by "Hua Zhang published in 2020"
TL;DR: A new one-dimensional halide perovskite ferroelectric N,N-dimethylallylammoniumCdCl3 (DMAACdCl 3) exhibits an above room-temperature ferro electric phase transition with a saturated polarization of 1.9 μC cm-2 and a coercive field of 5.0 kV cm-1.
Abstract: Piezoelectric materials with inherent mechanical-electric coupling effect are a crucial family of functional materials in high-end information technology. For practical applications, the transverse piezoelectric performance (d31 or d32) is mainly considered, because this parameter is a vitally important index to characterize the performance of piezoelectric thin films. However, the transverse piezoelectricity of the thin films as a key figure of merit is seldom mentioned in molecular ferroelectrics. Herein, we report that a new 1D halide perovskite ferroelectric N,N-dimethylallylammoniumCdCl3 (DMAACdCl3) exhibits an above room-temperature ferroelectric phase transition with a saturated polarization of 1.9 μC cm-2 and a coercive field of 5.0 kV cm-1. The thin film of DMAACdCl3 is successfully fabricated using an easy processing spinning method and maintains well ferroelectric properties verified by piezoresponse force microscopy (PFM). More significantly, the ferroelectric thin film offers superior transverse piezoelectricity with an in-plane piezoelectric response of about 41 pC N-1, which is about twice that of well-known piezoelectric polymer PVDF (21 pC N-1). Transverse piezoelectricity has been scarcely studied in molecular ferroelectrics, and its exploitation would play an important role in the design of next-generation smart piezoelectric devices.
36 citations
TL;DR: The metal-free approach has emerged as a promising alternative strategy for C-H borylation and has become one of the most important and efficient methods for the synthesis of organoboron compounds.
Abstract: In recent decades, C–H borylation has undergone rapid development and has become one of the most important and efficient methods for the synthesis of organoboron compounds. Although transition-metal catalysis dominates C–H borylation, the metal-free approach has emerged as a promising alternative strategy. This article briefly summarizes the history of metal-free aromatic C–H borylation, including early reports on electrophilic C–H borylation and recent progress in metal-free catalytic intermolecular C–H borylation; it also highlights our recent work on BF3·Et2O-catalyzed C2–H borylation of hetarenes. Despite these recent advances, comprehensive mechanistic studies on various metal-free catalytic aromatic C–H borylations and novel processes with a wider substrate scope are eagerly expected in the near future.
4 citations