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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. [ABSTRACT FROM AUTHOR]

Polycrystalline films of betaine phosphite (BPI) were grown by evaporation method on SiO2 and LiNbO3 substrates with interdigital transducers. Large (∼1 mm) single-crystalline blocks were visualized in a polarizing microscope in the reflection mode. Temperature dependences of the film capacity at frequencies 120 Hz–1 MHz exhibit a strong maximum at the temperature of the ferroelectric phase transition of BPI bulk crystals. The effect of a bias electric field was studied. Temperature variations in dielectric permittivity and electric field effect are analyzed using a thermodynamic model accounting for the substrate-film interaction. [ABSTRACT FROM AUTHOR]

Single crystals of L-histidine phosphite (L-Hist · H3РО3) have been grown from aqueous solution by slow cooling method. The results of elemental analysis, of X-ray-diffraction studies of the crystal structure, and the habitus of the obtained crystals are given. The elastic and piezoelectric coefficients have been measured on the plates with the (010) natural faces by the method of electromechanical resonance for stretching vibrations in the temperature range 295-340 K. Elastic compliance values s33 and s22 and the corresponding elastic-moduli values, piezoelectric coefficients d23 and d22, coefficients of electromechanical coupling, and temperature coefficient of the resonance frequency are obtained. A comparison is given with other crystals, which are compounds of amino acids with phosphorous or phosphoric acid. [ABSTRACT FROM AUTHOR]

Temperature dependence of the dielectric constant and longitudinal acoustic wave velocity were studied in betaine phosphite-betaine phosphate single crystals (BPI1-xBPx: x = 0-0.1) in temperature regions of antiferrodistortive (Tc1) and ferroelectric (Tc2) phase transitions. The admixture of BP to BPI leads to increase of the antiferrodistortive phase transition temperature Tc1(x) (Tc1(0.1) = 360 K, Tc1(0) = 355 K) and decrease of the dielectric anomaly at Tc1(x). The nonlinear temperature dependence of the inverse dielectric constant in the antiferrodistortive phase, the electric field effect on the dielectric constant and acoustic anomalies at the ferroelectric phase transition are described in the frames of the Landau-Ginzburg-Devonshire-type thermodynamic model with the biquadratic coupling between nonpolar and polar order parameters. [ABSTRACT FROM AUTHOR]