The presence of mobile ions complicates the implementation of voltage-modulated scanning probe microscopy techniques such as Kelvin probe force microscopy (KPFM). Overcoming this technical hurdle, however, provides a unique opportunity to probe ion dynamics and electrochemical processes in liquid environments and the possibility to unravel the underlying mechanisms behind important processes at the solid-liquid interface, including adsorption, electron transfer and electrocatalysis. Here we describe the development and implementation of electrochemical force microscopy (EcFM) to probe local bias-and time-resolved ion dynamics and electrochemical processes at the solid-liquid interface. Using EcFM, we demonstrate contact potential difference measurements, consistent with the principles of open-loop KPFM operation. We also demonstrate that EcFM can be used to investigate charge screening mechanisms and electrochemical reactions in the probe-sample junction. We further establish EcFM as a force-based imaging mode, allowing visualization of the spatial variability of sample-dependent local electrochemical properties.

Flexoelectric effect impact on the generalized susceptibility and soft phonons dispersion was not studied in the long-range ordered phases of ferroics. Within Landau-Ginzburg-Devonshire approach we obtained analytical expressions for the generalized susceptibility and phonon dispersion relations in the ferroelectric phase. The joint action of static and dynamic flexoelectric effect induces non-diagonal components of generalized susceptibility, which amplitude is proportional to the convolution of the spontaneous polarization with flexocoupling constants.The flexocoupling essentially broadens the k-spectrum of generalized susceptibility and leads to the additional "pushing away" of the optical and acoustic soft mode phonon branches. The degeneration of the transverse optic and acoustic modes disappears in the ferroelectric phase in comparison with the paraelectric phase due to the joint action of flexoelectric coupling and ferroelectric nonlinearity. Obtained results can be principally important for the theoretical analyses of the experimental data broad spectrum including neutron and Brillouin scattering.

The origin and influence of finite size effects on the nonlinear dynamics of space charge stored by multi-layer graphene on ferroelectric and resistivity of graphene channel were analyzed. Here, we develop a self-consistent approach combining the solution of electrostatic problems with the nonlinear Landau-Khalatnikov equations for ferroelectric. The size-dependent behaviors are governed by the relations between the thicknesses of multi-layer graphene, ferroelectric film and the dielectric layer.The appearance of charge and electro-resistance hysteresis loops and their versatility stem from the interplay of polarization reversal dynamics and its incomplete screening in an alternating electric field.These features are mostly determined by the dielectric layer thickness. The derived analytical expressions for electric fields and space charge density distribution in a multi-layer system enable knowledge-driven design of graphene-on-ferroelectric heterostructures with advanced performances.We further investigate the effects of spatially non-uniform ferroelectric domain structures on the graphene layers conductivity and predict its dramatic increase under the transition from multi-to single-domain state in ferroelectric. This intriguing effect can open new possibilities for the graphenebased sensors and explore the physical mechanisms underlying in the operation of graphene field effect transistor with ferroelectric gating.

We propose a self-consistent theoretical approach capable to describe the peculiarities of the anisotropic nanodomain formation induced by a charged AFM probe on non-polar cuts of ferroelectrics. The proposed semi-phenomenological approach accounts for the difference of the threshold fields required for the domain wall motion along non-polar X-and Y -cuts, and polar Z-cut of LiNbO 3 . The effect steams from the fact, that the minimal distance between the equilibrium atomic positions of domain wall and the profile of lattice pinning barrier appeared different for different directions due to the crystallographic anisotropy.Using relaxation-type equation with cubic nonlinearity we calculated the polarization reversal dynamics during the probe-induced nanodomain formation for different threshold field values. The different velocity of domain growth and consequently equilibrium domain sizes on X-, Y-and Z-cuts of LiNbO 3 originate from the anisotropy of the threshold field. Note that the smaller is the threshold field the larger are the domain sizes, and the fact allows explaining several times difference in nanodomain length experimentally observed on X-and Y-cuts of LiNbO 3 . Obtained results can give insight into the nanoscale anisotropic dynamics of polarization reversal in strongly inhomogeneous electric field.

The effective piezoelectric coefficients of twin walls in tetragonal ferroelectric are calculated in the framework of decoupling approximation and Landau-Ginzburg-Devonshire theory allowing for polarization gradient terms, electrostriction and flexoelectric coupling. Using an example of piezoelectric response of a 1 -a 2 twins to a homogeneous electric field, we show that the response is almost independent on the flexoelectric coupling, but is very sensitive to the values of polarization gradient coefficients. This behavior originates from the strong coupling between local dielectric susceptibility and the gradient coefficients. The enhancement of piezoelectric response from 10% up to a factor of 10 3 times is predicted. The local electromechanical response of the domain walls can thus provide information on the gradient terms in GLD expansion and pinning mechanisms of the ferroelectric domain walls. The observability of these effects by the piezoresponse force microscopy of electroded structures and impact on the functional properties of the systems with dense domain structures is analyzed.* morozo@i.com.ua † sergei2@ornl.gov 2

Dynamic Electrochemical Strain Microscopy (ESM) response of mixed ionic-electronic conductors is analysed in the framework of the Thomas-Fermi screening theory and Vegard law with accounting of the steric effects. The emergence of dynamic charge waves and nonlinear deformation of the surface as result of applying probing voltage is numerically explored. 2D maps of the strain and concentration distribution across the mixed ionic-electronic conductor and bias-induced surface displacements for ESM microscopy were calculated. Obtained numerical results can be of applied to quantify ESM response of Li-based solid electroytes, materials with resistive switching and electroactive ferroelectric polymers, which are of potential interest for flexible and high-density non-volatile memory devices

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Adnotacja. W artykule podkreślono, że regulacja warunków pracy w prawie pracy Ukrainy na obecnym etapie istnieje w dwóch głównych płaszczyznach: scentralizowanej i lokalnej. Akty prawne tradycyjnie należą do pierwszej kategorii i są obdarzone najwyższą mocą prawną. Obejmuje to Konstytucję Ukrainy, Kodeks Prawa Pracy Ukrainy, inne międzysektorowe i branżowe akty prawa pracy. Z kolei stosowanie lokalnych przepisów prawnych w przedsiębiorstwach, instytucjach i organizacjach jest najczęściej śledzone w zakresie regulacji czasu pracy i odpoczynku pracowników, płac i bezpieczeństwa pracy, ponieważ kwestie te wymagają bardziej elastycznego podejścia w zależności od charakteru pełnionych przez pracowników funkcji pracy.Słowa kluczowe: podmioty lokalnych regulacji prawnych, lokalne akty prawne, stosunek pracy, bezpieczeństwo i higiena pracy.