Molecular Materials

Perovskite ferroelectric bond-switching

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Science  26 May 2017:
Vol. 356, Issue 6340, pp. 817-818
DOI: 10.1126/science.356.6340.817-g

Ferroelectric materials are normally inorganic ceramics, such as barium titanate, but for flexible devices, molecular ferroelectrics that could readily form thin films are of interest. Xu et al. report that substitution of organic cations for potassium in an iron cyanide perovskite—[(CH3)3NOH]2[KFe(CN)6]—creates a ferroelectric with a high Curie temperature (402 K), where it undergoes a phase transition through a bond-switching mechanism from a low-temperature monoclinic ferroelectric phase (space group Cc) to a high-temperature cubic paraelectric phase (Fm3̄m). Thin films of this material showed rectangular polarization–electric field hysteresis loops at a relatively high driving frequency of 5 kHz and could be reversibly poled with the bias field from a probe tip.

J. Am. Chem. Soc. 10.1021/jacs.7b01334 (2017).

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