Lone-Pair-Electron-Driven Ionic Displacements in a Ferroelectric Metal-Organic Hybrid.
A displacive-type mechanism, which accounts for the occurrence of ferroelectricity in most inorganic ferroelectrics, is rarely found in molecule-based ferroelectrics. Its role is often covered by the predominant order-disorder one. Herein, we report a lone-pair-electron-driven displacive-type ferroelectric organic-inorganic hybrid compound, [H2dmdap][SbCl5] (1; dmdap = N,N-dimethyl-1,3-diaminopropane). The structure of 1 features a typical zigzag chain of [SbCl5]∞containing cis-connected anionic octahedra. The compound undergoes a second-order paraelectric-ferroelectric phase transition at 143 K (P21/c ↔ Pc) with a saturation polarization of 1.36 μC·cm-2and a coercive field of 3.5 kV·cm-1at 119 K. Theoretical study discloses the ferroelectricity mainly originating from the relative displacements of the Sb and Cl ions in the crystal lattice, which are driven by the 5s2lone-pair electrons of the SbIIIcenter. Furthermore, on the basis of analysis, possible routes are suggested to enhance ferroelectric polarization in this class of compounds.
Ordered Matter Science Research Center, Southeast University , Nanjing 211189, Jiangsu, China.
Wen-Ping
WP
Zhao
Ordered Matter Science Research Center, Southeast University , Nanjing 211189, Jiangsu, China.
Chao
C
Shi
Consiglio Nazionale delle Ricerche (CNR-SPIN) , Via Vetoio, I-67010 L'Aquila, Italy.|International Centre for Quantum and Molecular Structures and Physics Department, Shanghai University , 99 Shangda Road, Shanghai 200444 China.
Alessandro
A
Stroppa
Consiglio Nazionale delle Ricerche (CNR-SPIN) , Via Vetoio, I-67010 L'Aquila, Italy.|Institut fuer Theoretische Physik und Astrophysik, Universitaet Wuerzburg , Am Hubland Campus Sued, Wuerzburg 97074, Germany.
Domenico
D
Di Sante
Institute of Physical Chemistry of Roumanian Academy , Splaiul Independentei 202, Bucharest 060021, Romania.
Fanica
F
Cimpoesu
Ordered Matter Science Research Center, Southeast University , Nanjing 211189, Jiangsu, China.
Wen
W
Zhang