resumo
Molecular ferroelectrics are becoming an important area of research due to their ability to form a variety of structures exhibiting the desired properties. However, the precise control over the assembly of molecular building blocks for the design and synthesis of photoresponsive molecular ferroelectrics remains a considerable challenge. Here, we report a new hybrid high-temperature ferroelectric, (Me2NH2)[NaFe(CN)(5)(NO)], by judiciously assembling inorganic photochromic nitroprusside anion, as the framework building block, and polar organic cation Me2NH2+, as the dipole-moment carrier, into the crystal lattice. Ferroelectricity arises through the synergetic ordering of Me2NH2+ below 408 K. Piezoresponse force microscopy witnessed the presence of 180 degrees ferroelectric domains and evidenced polarization switching by repeatedly applying an external electric field. Irradiation of the N-bound nitrosyl ligand (ground state) leads to two different conformations: isonitrosyl O-bound (metastable state I) and side-on nitrosyl conformation (metastable state II). Such photoisomerization realized in solid-state molecular ferroelectrics allows for the photoswitching between the ferroelectric ground state and the metastable state. These results pave the way for new design approaches toward developing next-generation photostimulated ferroelectric materials at the molecular level.
palavras-chave
PHASE-TRANSITION; PEROVSKITE; POLARIZATION; CRYSTALS; NITROPRUSSIDE; BEHAVIOR; ISOMERS; ORDER; STATE
categoria
Chemistry
autores
Xu, WJ; Romanyuk, K; Martinho, JMG; Zeng, Y; Zhang, XW; Ushakov, A; Shur, V; Zhang, WX; Chen, XM; Kholkin, A; Rocha, J
nossos autores
Andrei Kholkin
Investigador Principal
João Rocha
Prof. Catedráticoagradecimentos
This work was supported by NSFC (Grants 21722107, 21821003, 21805312, and 21671202), Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program (Grant 2017BT01C161). This work (including the grant of W.-J.X.) was also developed within the scope of the project CICECO-Aveiro Institute of Materials, Grants UIDB/50011/2020 and UIDP/50011/2020, financed by national funds through the FCT/MEC and when appropriate cofinanced by FEDER under the PT2020 Partnership Agreement. The equipment of the Ural Center for Shared Use Modern Nanotechnology UrFU was used. The work was supported by Government of the Russian Federation (Act 211, Agreement 02.A03.21.0006). It is also funded by national funds (OE), through FCT (Fundacao para a Ciencia e a Tecnologia), I.P., in the scope of the framework contract foreseen in the numbers 4, 5, and 6 of Article 23, of the Decree-Law 57/2016, of August 29, changed by Law 57/2017, of July 19. We thank Prof. Damien Thompson from the University of Limerick and Prof. Laura M. Ilharco from the Universidade de Lisboa for helpful discussions on piezoelectricity and access to IR equipment, respectively.