Author, as appears in the article.: Wang, Fei; Lang, Zhongling; Yan, Likai; Stroppa, Alessandro; Poblet, Josep M.; de Graaf, Coen;

Department: Química Física i Inorgànica

URV's Author/s: De Graaf, Cornelis / Poblet Rius, Josep Maria / Wang, Fei

Keywords: Single molecule Positive ions Polyoxometalates Polarization Permanent dipoles Molecules Modern theory of polarization Interconversions Ground state Ferroelectricity Ferroelectric property Experimental values Electric polarization Density functional theory studies Density functional theory

Abstract: A detailed study on the single-molecule ferroelectric property of Preyssler-type polyoxometalates (POMs), [M3+P5W30O110](12-) (M = La, Gd, and Lu), is performed by density functional theory calculations. Linked to one H2O molecule, the cation (M3+) encapsulated in the cavity of the Preyssler framework is off-centered, and it generates a permanent dipole, which is essential for a ferroelectric ground state. Accompanied with a 180 degrees rotation of H2O, the switching of M3+ between two isoenergetic sites on both sides of the cavity results in a calculated barrier of 1.15 eV for Gd3+, leading to the inversion of electric polarization. The height of the barrier is in good agreement with the experimentally measured barrier for the Tb3+ ion, whose ionic radius is similar to Gd3+. The total polarization value of the crystal is estimated to be 4.7 mu C/cm(2) as calculated by the modern theory of polarization, which is quite close to the experimental value. Considering that the order of contributions to the polarization is M3+-H2O > counter-cations (K+) > [P5W30O110](15-), the interconversion of M3+-H2O between the two isoenergetic sites is predicted to be the main origin of ferroelectricity with a polarization contribution of 3.4 mu C/cm(2); the K+ counter-cations contribute by 1.2 mu C/cm(2) and it cannot be disregarded, while the framework appears to contribute negligibly to the total polarization. Our study suggests that a suitable choice of M3+-H2O could be used to tune the single-molecule ferroelectricity in Preyssler-type polyoxometalates.

Thematic Areas: Química Physics, applied Nanoscience & nanotechnology Materials science, multidisciplinary Materials science (miscellaneous) Materials science (all) Materiais General materials science General engineering Engineering (miscellaneous) Engineering (all) Engenharias iii Engenharias ii Ciências agrárias i Astronomia / física

licence for use: https://creativecommons.org/licenses/by/3.0/es/

Author's mail: coen.degraaf@urv.cat josepmaria.poblet@urv.cat fei.wang@urv.cat

Author identifier: 0000-0001-8114-6658 0000-0002-4533-0623 0000-0001-5106-5793

Record's date: 2023-02-23

Journal volume: 9

Papper version: info:eu-repo/semantics/publishedVersion

Link to the original source: https://aip.scitation.org/doi/10.1063/5.0035778

Licence document URL: http://repositori.urv.cat/ca/proteccio-de-dades/

Papper original source: Apl Materials. 9 (2):

APA: Wang, Fei; Lang, Zhongling; Yan, Likai; Stroppa, Alessandro; Poblet, Josep M.; de Graaf, Coen; (2021). Density functional theory study of single-molecule ferroelectricity in Preyssler-type polyoxometalates. Apl Materials, 9(2), -. DOI: 10.1063/5.0035778

Article's DOI: 10.1063/5.0035778

Entity: Universitat Rovira i Virgili

Journal publication year: 2021

Publication Type: Journal Publications