AFM Visualization of Ferroelastic and Ferroelectric Domains in 2-Methylbenzimidazole С8H8N2 Crystals

The domain structure on the surface of 2-methylbenzimidazole (MBI) crystals is studied using various modes of atomic-force microscopy, which made it possible to visualize the surface potential distribution. MBI crystals are grown by evaporation from a saturated ethanol solution. Using the scanning Kelvin probe microscopy mode, the potential distribution is visualized on the (001) cleavages of a single crystal, which is a periodic structure of charged stripes oriented along the 〈110〉 tetr axis. This pattern can be explained by the presence of a system of ferroelastic domains with charged domain walls on the surface, which compensates deformation in the surface layers occurring during cleavage. An equilibrium structure of ferroelectric domains with a polarization component perpendicular to the surface is found on the {110} microcrystal surface using the scanning Kelvin probe microscopy mode. The electrostatic force microscopy mode makes it possible to visualize ferroelastic domain walls. It is shown that, in the case of a microcrystal, the action of a locally applied electric pulse causes the displacement of both ferroelectric and ferroelastic domain walls. The potential distribution over the (001) cleavage surface of the single crystal after external action remains unchanged.