TY  - JOUR
AU  - Gronych, Lara M.
AU  - Kraft, Marvin A.
AU  - Hartmann, Matthias
AU  - Faka, Vasiliki
AU  - Glikman, Dana
AU  - Koers, Iven
AU  - Li, Cheng
AU  - Newnham, Jon
AU  - Braunschweig, Björn
AU  - Zeier, Wolfgang
AU  - Martinez de Irujo-Labalde, Xabier
TI  - Proton Ordering Induces a Polar Structure in the Antiferromagnetic Solid Proton Conductor $FeH_6(PO_4)_3$
JO  - Journal of the American Chemical Society
VL  - 147
IS  - 37
SN  - 0002-7863
CY  - Washington, DC
PB  - ACS Publications
M1  - FZJ-2025-04074
SP  - 33859 - 33869
PY  - 2025
AB  - Materials exhibiting coexisting exploitable properties often result in especially attractive behavior from both fundamental and applied perspectives. In particular, magnetoelectric materials combining ferroelectric and magnetic properties are increasingly becoming paramount nowadays. Here, we show that $FeH_6(PO_4)_3$ exhibits proton conductivity and the coexistence of magnetic and polar structural features, suggesting that such frameworks may be of broader interest beyond the field of proton conductors. By a combination of neutron diffraction and second harmonic generation experiments, we have demonstrated that $FeH_6(PO_4)_3$ crystallizes in the polar $R3c$ space group. Inversion symmetry breaking is triggered by a polar proton ordering within the structure. In $FeH_6(PO_4)_3$, this particular cation ordering in combination with the polar displacement of the adjacent structural units results in a polar crystal structure with a calculated net polarization of approximatel $10 μC cm{^–2}$ between 10 and 300 K. Together with an antiferromagnetic state below 28 K, determined from a combination of neutron diffraction and magnetic measurements and associated with the particular $Fe^{3+}$ octahedral arrangement, the result is the coexistence of both properties. By a detailed study of this system with a full description of the crystal structure as well as the ionic and magnetic properties, we aim to spark further investigations in magnetoelectric materials existing in the solid ionic conductor phase space.
LB  - PUB:(DE-HGF)16
DO  - DOI:10.1021/jacs.5c10508
UR  - https://juser.fz-juelich.de/record/1047018
ER  -