DOI: 10.17586/2226-1494-2016-16-5-801-808


E. V. Balashova, B. B. Krichevtsov, F. B. Svinarev, N. V. Zaitseva

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For citation: Balashova E.V., Krichevtsov B.B., Svinarev F.B., Zaitseva N.V. Thin films of a new organic single-component ferroelectric 2-methylbenzimidazole. Scientific and Technical Journal of Information Technologies, Mechanics and Optics, 2016, vol. 16, no. 5, pp. 801–808. doi: 10.17586/2226-1494-2016-16-5-801-808


 Subject of Research.We present results of structural and dielectric study of organic ferroelectric 2-methylbenzimidazole (MBI) thin films. Method. The films have been grown on substrates of leuco-sapphire, fused and crystalline silica, neodymium gallate, bismuth germanate, gold, aluminium, platinum. The films have been grown by two different methods: substrate covering by ethanol solution of MBI and subsequent ethanol evaporation; sublimation at the temperature near 375 K under atmospheric pressure. Crystallographic orientation studies have been performed by means of «DRON-3» X-ray diffractometer, block structure of the films has been determined by «LaboPol-3» polarizing microscope. Small-signal dielectric response has been received with the use of «MIT 9216A» digital LCR-meter, while strong-signal dielectric response has been studied by Sawyer-Tower circuit. Main Resuts. We have shown that the films obtained by evaporation are continuous and textured. Obtained film structure depends on the concentration of the solution. Films may consist of blocks that are splitted crystals like spherulite. Spontaneous polarization components in such films may be directed both perpendicularly and in the film plane. We have also obtained structures consisting of single-crystal blocks with spontaneous polarization components being allocated in the film plane. Block sizes vary from a few to hundreds of microns. Films obtained by sublimation are amorphous or dendritic. The dielectric properties of the films obtained by evaporation have been studied. We have shown that the dielectric constant and dielectric loss tangent increase under heating. The dielectric hysteresis loops are observed at the temperature equal to 291-379 K. The remnant polarization increases with temperature for constant amplitude of the external electric field, and achieves 4.5mC/cm2, while the coercive field remains constant. We propose that such behavior is explained by increase of the number of crystallites with switchable polarization due to decrease in the coercive field under heating. The remnant polarization decreases with frequency increase. Practical Relevance. Proposed method of ferroelectric films manufacture is characterized by low cost and convenience. Unlike many other ferroelectrics, the films contain no lead and rare metals. MBI films demonstrate the low value of the coercive fields. This paper may be useful for electronic components developers.

Keywords: 2-methylbenzimidazole, MBI, ferroelectricity, organic crystals, thin films, Sawyer-Tower circuit

Acknowledgements. This study was supported in part by the Russian Foundation for Basic Research (project No. 16-02-00399). The authors are grateful to S.Y. Belova for profilometric measurements.


1. Horiuchi S., Ishii F., Kumai R. et al. Ferroelectricity near room temperature in co-crystals of nonpolar organic molecules. Nature Materials, 2005, vol. 4, no. 2, pp. 163–166. doi: 10.1038/nmat1298
2. Horiuchi S., Tokura Y. Organic ferroelectrics. Nature Materials, 2008, vol. 7, no. 5, pp. 357–366. doi: 10.1038/nmat2137
3. Horiuchi S., Kagawa F., Hatahara K. et al. Above-room-temperature ferroelectricity and antiferroelectricity in benzimidazoles. Nature Communications, 2012, vol. 3, art. 2322. doi: 10.1038/ncomms2322
4. Fu D.-W., Cai H.-L., Liu Y. et al. Diisopropylammonium bromide is a high-temperature molecular ferroelectric crystal. Science, 2013, vol. 339, no. 6118, pp. 425–428. doi: 10.1126/science.1229675
5. Li J., Liu Y., Zhang Y., Cai H.-L., Xiong R.-G. Molecular ferroelectrics: where electronics meet biology. Physical Chemistry Chemical Physics, 2013, vol. 15, no. 48, pp. 20786–20796. doi: 10.1039/c3cp52501e
6. Thompson N.J., Jandl A.C., Spalenka J.W., Evans P.G. Thin films of a ferroelectric phenazine/chloranilic acid organic cocrystal. Journal of Crystal Growth, 2011, vol. 327, pp. 258–261. doi: 10.1016/j.jcrysgro.2011.05.027
7. Gao W., Chang L., Ma He et al. Flexible organic ferroelectric films with a large piezoelectric response. NPG Asia Materials, 2015, vol. 7, art. e189. doi: 10.1038/am.2015.54
8. Noda Y., Yamada T., Kobayashi K., et al. Few-volt operation of printed organic ferroelectric capacitor. Advanced Materials, 2015, vol. 27, no. 41, pp. 6475–6481. doi: 10.1002/adma.201502357
9. Obodovskaya A.E., Starikova Z.A., Belous S.N., Pokrovskaya I.E. Crystal and molecular structure of 2-methylbenzimidazole. Journal of Structural Chemistry, 1991, vol. 32, no. 3, pp. 421–422. doi: 10.1007/BF00745764
10. Zielinski W., Katrusiak A. Colossal monotonic response to hydrostatic pressure in molecular crystal induced by a chemical modification. Crystal Growth and Design, 2014, vol. 14, no. 9, pp. 4247–4253. doi: 10.1021/cg5008457
11. Balashova E.V., Krichevtsov B.B., Lemanov V.V. Ferroelectric betaine phosphite films: growth, optical imaging, and dielectric properties. Journal of Applied Physics, 2008, vol. 104, no. 12, art. 126104. doi: 10.1063/1.3053081
12. Balashova E.V., Krichevtsov B.B., Pankova G.A., Lemanov V.V. Structural and dielectric properties of glycine phosphite thin films. Ferroelectrics, 2012, vol. 433, no. 1, pp. 138–145. doi: 10.1080/00150193.2012.696414
13. Balashova E.V., Krichevtsov B.B., Svinarev F.B., Lemanov V.V. Ferroelectric films of deuterated glycine phosphite: Structure and dielectric properties. Physics of the Solid State, 2013, vol. 55, no. 5, pp. 995–1001. doi: 10.1134/S106378341305003X
14. Balashova E.V., Krichevtsov B.B., Yurko E.I., Pankova G.A. Dielectric properties of thin films of partially deuterated betaine phosphite with large- and small-block structures. Physics of the Solid State, 2014, vol. 56, no. 10, pp. 1997–2004. doi: 10.1134/S1063783414100059
15. Balashova E.V., Krichevtsov B.B. Ferroelectric thin films of betaine phosphite, glycine phosphite and of their deuterated analogs. Ferroelectrics, 2014, vol. 469, no. 1, pp. 26–42. doi: 10.1080/00150193.2014.948347
16. Balashova E.V., Krichevtsov B.B., Zaitseva N.V., Yurko E.I., Svinarev F.B. Dielectric and structural properties of ferroelectric betaine arsenate films. Physics of the Solid State, 2014, vol. 56, no. 12, pp. 2376–2383. doi: 10.1134/S1063783414120038
17. Balashova E.V., Krichevtsov B.B., Yurko E.I., Svinarev F.B., Pankova G.A. Dielectric properties of ferroelectric betaine phosphite crystals with a high degree of deuteration. Physics of the Solid State, 2015, vol. 57, no. 12, pp. 2382–2388. doi: 10.1134/S1063783415120082 



 Fig. 1. The structural formula of 2-methylbenzimidazole molecule

 Fig.2. MBI type crystals of spherulite growing in an alcohol solution. Photos are taken in the crossed polarizers at different rotation angles of the sample relative to the polarizers (a)–(b). The overview area size is 4×3 mm2

 Fig.3. Diffractograms of two MBI films grown on leucosapphire substrates. The peaks corresponding to MBI and the peaks caused by reflection from the gold electrodes are specified. β – the line caused by reflection of CuKβradiation: the film of A type (a); the film of B type (b)

 Fig.4. Photos of MBI films of A type (a)–(C) and B type (g). Photos (a)–(b) are made in crossed polarizers and photos (b)–(d) – in parallel polarizers. Alternating light and dark bands represent the inter-digital structure of electrodes; the width of one strip is 50 microns

 Fig. 5. Dielectric hysteresis loops in the MBI films at different temperatures.

UЕ– the voltage applied to inter-digital structures, UP –the voltage on reference capacitor proportional to Ppolarization. Linear dependence UP(UЕ) due to capacity structure has been deducted: A type film (a), B type film (b)


Fig. 6. Dielectric hysteresis loops in the MBI films at various frequencies. Linear dependence UP(UЕ) due to the structure capacity has been deducted: A type film with the temperature of 294 K (a); B type film with the temperature of 295 K (b)

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