Temperature evolution of (quinuclidinium)[FeCl4]: a plastic/polar magnetic hybrid compound with a giant dielectric constant. Issue 33 (29th June 2020)

• Record Type: Journal Article
• Authors: González-Izquierdo, Palmerina; Fabelo, Oscar; Canadillas-Delgado, Laura; Beobide, Garikoitz; Vallcorba, Oriol; Sánchez-Andújar, Manuel; Fernández-Díaz, María Teresa; de Pedro, Imanol
• Is Part Of: Journal of materials chemistry. Volume 8:Issue 33(2020)
• Page Start: 11389
• Page End: 11398
• Publication Date: 2020-06-29
• Subjects: Materials -- Periodicals; Chemistry, Analytic -- Periodicals; Optical materials -- Research -- Periodicals; Electronics -- Materials -- Research -- Periodicals; 543.0284
• DOI: 10.1039/d0tc02341h
• Languages: English
• ISSNs: 2050-7526

Abstract

Abstract : The temperature evolution of (quinuclidinium)[FeCl4 ] shows the occurrence of an intricate series of phase transitions, involving notable modifications on the physical properties. Abstract : The temperature evolution of the physical properties of the (quinuclidinium)[FeCl4 ] compound shows an unprecedented series of phase, structural and magnetic transitions. Above 390 K, a plastic phase (also termed as "rotator phases") is observed (phase I). Between 390 K and 280 K, an intermediate phase solved in a non-centrosymmetric space group has been characterized. Crystallographic studies show that the compound crystallizes in the Pbc 21 polar space group (phase II), and therefore the phase transition between I and II involves a paraelectric-to-polar phase transition. This result is confirmed by complex dielectric permittivity. Moreover, the real part of the dielectric permittivity shows a giant increase above 390 K, reaching a maximum value of 10 5 that is notably larger than any other hybrid compound previously reported. Below 280 K, a third structural phase transition is observed, which involves the doubling of the unit cell and a change of symmetry due to the blocking of counter-ions, phase III crystallizing in the Pbca centrosymmetric space group. Below 3.5 K, long-range magnetic order is detected. Neutron diffraction below this order temperature suggests breaking of symmetry and the magnetic structure in phase IV was solved in the P 21 ′21 ′21 Shubnikov space group, giving rise to a ferrimagnetic structure that allows a net ferromagnetic signal along the c -axis.