Isostructural phase transition, quasielastic neutron scattering and magnetic resonance studies of a bistable dielectric ion-pair crystal [(CH3)2NH2]2KCr(CN)6. Issue 13 (1st March 2019)

• Record Type: Journal Article
• Authors: Rok, M.; Bator, G.; Zarychta, B.; Dziuk, B.; Repeć, J.; Medycki, W.; Zamponi, M.; Usevičius, G.; Šimėnas, M.; Banys, J.
• Is Part Of: Dalton transactions. Volume 48:Issue 13(2019)
• Page Start: 4190
• Page End: 4202
• Publication Date: 2019-03-01
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/c8dt05082a
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : Ferroelastic phase transition in novel HOIP crystal with dielectric switchable properties. Abstract : We have synthesised and characterised a novel organic–inorganic hybrid crystal, [(CH3 )2 NH2 ]2 KCr(CN)6 . The thermal DSC, TMA, DTG and DTA analyses indicate two solid-to-solid structural phase transitions (PTs). According to the X-ray diffraction experiments, the first PT at 220 K is isostructural, since it does not involve a change of the space group. This transition occurs between the states, where the (CH3 )2 NH2 + cations are orientationally disordered and ordered (frozen). The other reversible PT at 481 K leads to a melt-like phase similar to the one observed in plastic crystals or polar liquids. Dielectric spectroscopy has been used to characterise the switching properties of the dipole moments in the vicinity of the PTs. Continuous-wave electron paramagnetic resonance spectroscopy was employed to investigate the effect of ordering on the local environment of the Cr 3+ ions. We have also applied the quasielastic neutron scattering (QENS) technique as well as 1 H NMR spectroscopy to measure the dynamics of the (CH3 )2 NH2 + cations residing in the inorganic framework.