东南大学熊仁根团队制备了具有与钛酸钡相当的大机电耦合因子的英寸级分子铁电晶体。相关研究成果于2022年11月25日发表于国际顶尖学术期刊《美国化学会杂志》。

与广泛使用的无机对应物相比，具有大压电响应的分子铁电体由于其重量轻、机械柔性和易于制备的优点而被长期寻求。代表性地是，已发现分子铁电晶体[Me3NCH2Cl]CdCl3（TMCM-CdCl₃）显示出大压电系数d33(220pC/N)，超过BaTiO₃（You等人，Science2017, 357, 306–309）。然而，尽管分子铁电体的d33已经取得了巨大的进步，但其机电耦合因子k33（这对于包括超声换能器和致动器在内的各种压电应用至关重要）很少被探索，并且远远低于无机铁电体的水平。这种情况的主要原因是生长大尺寸晶体的巨大挑战，这是测量k33的关键限制因素。

该文中，研究人员制备了具有高d33（383 pC/N）的英寸级有机-无机钙钛矿铁电TMCM-CdCl3晶体，用于通过共振法研究其压电响应，包括k33（0.483）。这样的高k33（0.483）比其他分子铁电体大得多，并且与BaTiO3（0.5）相当。此外，TMCM-CdCl₃具有13.03GPa的低弹性模量，比BaTiO₃的弹性模量低一个数量级。该发现有助于探索用于柔性和便携式压电装置分子铁电体中的大机电耦合因素。

附：英文原文

Title: Inch-Size Molecular Ferroelectric Crystal with a Large Electromechanical Coupling Factor on Par with Barium Titanate

Author: Hui-Peng Lv, Wei-Qiang Liao, Yu-Meng You, Ren-Gen Xiong

Issue&Volume: November 25, 2022

Abstract: Molecular ferroelectrics with large piezoelectric responses have long been sought for their advantages of light weight, mechanical flexibility, and easy preparation, in contrast to the widely used inorganic counterparts. Representatively, a molecular ferroelectric crystal [Me3NCH2Cl]CdCl3 (TMCM-CdCl3) has been found to show a large piezoelectric coefficient d33 of 220 pC/N exceeding that of BaTiO3 (You et al. Science2017, 357, 306–309). However, although the d33 of molecular ferroelectrics has achieved great progress, their electromechanical coupling factor k33, which is essential for various piezoelectric applications, including ultrasonic transducers and actuators, was rarely explored and is far below the level of inorganic ferroelectrics. The major reason for this situation is the great challenge of growing large-size crystals which is a key limiting factor for measuring k33. Here, we grew inch-size crystals of organic–inorganic perovskite ferroelectric TMCM-CdCl3 with a high d33 (383 pC/N) for investigating its piezoelectric responses including the k33 (0.483) by the resonance method. Such high k33 (0.483) is much larger than those of other molecular ferroelectrics and competitive with that of BaTiO3 (0.5). In addition, TMCM-CdCl3 has a low elastic modulus of 13.03 GPa, an order of magnitude lower than that of BaTiO3. This finding sheds light on the exploration of large electromechanical coupling factors in molecular ferroelectrics for potential applications in flexible and portable piezoelectric devices.

DOI: 10.1021/jacs.2c11213

Source: https://pubs.acs.org/doi/10.1021/jacs.2c11213