Ferroelectric Behavior of a Hexamethylenetetramine‐Based Molecular Perovskite Structure.

Morita, Hagino; Tsunashima, Ryo; Nishihara, Sadafumi; Inoue, Katsuya; Omura, Yuriko; Suzuki, Yasutaka; Kawamata, Jun; Hoshino, Norihisa; Akutagawa, Tomoyuki

We report the development of a molecular ferroelectric material inspired by the hexamethylenetetramine (hmta) non‐centrosymmetric molecular rotator. The bromide salt of diprotonated hmta (hmtaH2) crystalized as (hmtaH2)(NH4)Br3 in a metal‐free ABX3 perovskite‐type structure, in which the A and B sites are occupied by hmtaH22 and ammonium cations, respectively. The compound crystallized in the Pma2 polar space group. A distorted polar perovskite structure formed owing to the distortion of {(NH4)Br6} octahedrons that are stabilized through the formation of NH⋅⋅⋅Br hydrogen bonds and the orientational ordering of positive charges on the non‐centrosymmetric hmtaH2 molecules. This spontaneous polarization exhibited ferroelectric behavior with a nominally high Curie temperature (>400 K), in which the electrical switching of polarization originates from the rotation of the hmtaH2 unit.

FERROELECTRIC materials; METHENAMINE; PEROVSKITE; BROMIDES; CURIE temperature

Angewandte Chemie, 2019, Vol 131, Issue 27, p9282

0044-8249

Academic Journal

10.1002/ange.201905087