Probing ferroic transitions in a multiferroic framework family: a neutron diffraction study of the ammonium transition metal formates

Lawler, J.M.M. and Manuel, P. and Thompson, A.L. and Saines, P.J. (2015) Probing ferroic transitions in a multiferroic framework family: a neutron diffraction study of the ammonium transition metal formates. Dalton Transactions, 44 (25). pp. 11613-11620. ISSN 1477-9226. (doi:https://doi.org/10.1039/c5dt00733j) (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided)

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Official URL
http://dx.doi.org/10.1039/c5dt00733j

Abstract

This study probes the magnetic and ferroelectric ordering of the NH<inf>4</inf>M(HCO<inf>2</inf>)<inf>3</inf> (M = Mn2+, Fe2+, Co2+ and Ni2+) frameworks using neutron diffraction, improving the understanding of the origins of the properties of these fascinating multiferroics. This rare study of the magnetic structure of a family of metal-organic frameworks shows that all four compounds exhibit antiferromagnetic coupling between neighbouring cations bridged by formate ligands. The orientation of the spin, however, changes in a highly unusual way across the series with the spins aligned along the c-axis for the Fe2+ and Ni2+ frameworks but lying in the ab plane for the other members of the series. This work also sheds new light on the nature of the ferroelectric order-disorder transition in these materials; probing changes in the ammonium cation across the transition and also shows that the Ni2+ framework does not undergo a transition to the polar P6<inf>3</inf> phase due to the smaller size of the Ni2+ cation. Finally trends in their anisotropic negative thermal expansion, which potentially enhances their ferroic behaviour, are quantified.

Item Type: Article
Uncontrolled keywords: Antiferromagnetism, Crystalline materials, Ferroelectric materials, Ferroelectricity, Iron compounds, Manganese, Neutron diffraction, Nickel, Order disorder transitions, Organometallics, Positive ions, Thermal expansion, Ammonium cations, Antiferromagnetic coupling, Ferroelectric order, Ferroics, Metal organic framework, Multiferroics, Negative thermal expansion, Neutron diffraction studies, Transition metals
Subjects: Q Science > QC Physics > QC173.45 Condensed Matter
Q Science > QD Chemistry > QD478 Solid State Chemistry
Divisions: Faculties > Sciences > School of Physical Sciences > Functional Materials Group
Depositing User: Paul Saines
Date Deposited: 06 Oct 2015 15:12 UTC
Last Modified: 07 Oct 2015 09:20 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/50712 (The current URI for this page, for reference purposes)
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