Above-room-temperature ferroelectricity and antiferroelectricity in benzimidazoles

作者：Horiuchi Sachio^*; Kagawa Fumitaka; Hatahara Kensuke; Kobayashi Kensuke; Kumai Reiji; Murakami Youichi; Tokura Yoshinori

来源：Nature Communications, 2012, 3: 1308.

DOI：10.1038/ncomms2322

The imidazole unit is chemically stable and ubiquitous in biological systems; its proton donor and acceptor moieties easily bind molecules into a dipolar chain. Here we demonstrate that chains of these amphoteric molecules can often be bistable in electric polarity and electrically switchable, even in the crystalline state, through proton tautomerization. Polarization-electric field (P-E) hysteresis experiments reveal a high electric polarization ranging from 5 to 10 mu C cm(-2) at room temperature. Of these molecules, 2-methylbenzimidazole allows ferroelectric switching in two dimensions due to its pseudo-tetragonal crystal symmetry. The ferroelectricity is also thermally robust up to 400 K, as is that of 5,6-dichloro-2-methyl-benzimidazole (up to similar to 373 K). In contrast, three other benzimidazoles exhibit double P-E hysteresis curves characteristic of antiferroelectricity. The diversity of imidazole substituents is likely to stimulate a systematic exploration of various structure-property relationships and domain engineering in the quest for lead- and rare-metal-free ferroelectric devices.

• 出版日期2012-12