The diffuseness of the ferroelectric phase transition in ${\mathrm{PbMg}}_{1/3}$${\mathrm{Nb}}_{2/3}$${\mathrm{O}}_{3}$ is proposed to be due quenched random electric fields originating from charged compositional fluctuations. They are responsible for extreme critical slowing down, freezing into nanometric domains, and slow relaxation polarization below ${\mathit{T}}_{\mathit{c}}$\ensuremath{\sim}212 K. Barkhausen jumps during poling exclude glassiness, which was conjectured previously. At...

This review covers recent experimental and theoretical investigations into cooperative phenomena in crystals containing off-center ions. These have attracted much attention years because of a general interest disordered systems, particular spin glasses, whose electrical analog is the dipole glass. Specific features glass state alkali halide with ions are discussed compared glasses. Experimental studies performed demonstrated that highly polarizable can at certain concentrations induce...

Within the Landau-Ginsburg-Devonshire phenomenological approach we study ferroic nanosystem properties changes caused by flexoeffect (flexoelectric and flexomagnetic) existing spontaneously due to inhomogeneity of order parameters. An exact solution for spatially inhomogeneous mechanical displacement vector allowing flexocoupling contribution was found nanowires thin pills. Strong influence on nanorods pills leads displacements atoms resulting into unit-cell symmetry changes, which lead...

Ferroelectric nanoparticles of different shapes and their nanocomposites are actively studied by modern physics. Because applications in many fields nanotechnology, the size effects possible disappearance ferroelectricity at a critical particle volume attract growing scientific interest. In this paper we study cylindrical nanoparticle phase diagrams allowing for effective surface tension depolarization field influence. The Euler-Lagrange equations were solved direct variational method....

We investigated the possible formation and segregation of oxygen vacancies near surface SnO${}_{2}$ thin films from $K$-edge x-ray emission absorption spectra found that distribution O 2$p$ unoccupied states for ferromagnetic is different postannealed under atmosphere showing diamagnetic behavior. This spectroscopic result suggests can be source surface-induced magnetism in films. possibility was then explored by calculating lowest energy levels structural defects (impurities or neutral...

Theoretical analysis based on the Landau-Ginzburg-Devonshire (LGD) theory is used to show that product effect of flexoelectricity and rotostriction can lead a spontaneous polarization in vicinity antiphase boundaries, ferroelastic twin walls, surfaces interfaces octahedrally tilted phase otherwise non-ferroelectric perovskites such as CaTiO3, SrTiO3, EuTiO3. As an example, we numerically demonstrate large order 1-5muC/cm2 at SrTiO3 antidistortive boundaries temperatures lower than...

A model for ferroelectric relaxors such as PMN, PSN and PLZT giving a quantitative description of their properties phase diagrams is proposed within the framework random field theory. In this model, are considered systems with sites orientations electric dipoles, lattice vacancies, antisite ions other defects well impurities embedded into paraelectric phase, which to be `host' these materials.

General approach for consideration of primary ferroic (ferroelectric, ferromagnetic, ferroelastic) nanoparticles phase transitions was proposed in phenomenological theory framework. The surface stress, order parameter gradient, striction as well depolarization and demagnetization effects were included into the free energy. strong intrinsic stress under curved nanoparticle shown to play important role shift transition temperature (if any) up appearance new ordered absent bulk ferroic....

Abstract We construct a Landau–Ginzburg thermodynamic potential, and the corresponding phase diagram for pristine slightly doped bismuth ferrite, ferroelectric antiferromagnet at room temperature. The potential is developed based on new X-ray neutron diffraction experiments complementing available data. demonstrate that strong biquadratic antiferrodistortive-type coupling key to quantitative description of Bi 1− x La FeO 3 multiferroic including temperature stability antiferromagnetic,...

The influence of the mismatch effect on thin ferroelectric film properties has been studied in phenomenological theory framework. polarization dependent part surface energy that defined boundary conditions for Euler–Lagrange differential equation was written as a tension energy. latter expressed via and tensor related to substrate lattice constants thermal expansion coefficients. interfacial strain caused by induces additional Pm piezoelectric arises near any film.

Investigations of impurity centers, electrical resistivity and microstructure BaTiO3 ceramics doped with rare-earth ions Y, La, Nd, Sm, Dy Lu at concentrations x = 0.001–0.005 were carried out. Electron paramagnetic resonance, X-ray diffraction electron microscopy used for measurements. The most intense EPR lines shown to belong complexes Fe3+–VO Ti3+–Ln3+ (Ln ion, VO oxygen vacancy). A change in symmetry the center transition temperature from ferroelectric paraelectric phase has been...

We show that the flexomagnetic effect leads to new linear flexomagnetoelectric (FME) coupling in bulk and nanosized materials, where polarization (anti)magnetization vectors are spatially inhomogeneous due external or internal forces. The FME is proportional product of gradients (anti)magnetization, polarization, flexomagnetic, flexoelectric tensors. Due gradient nature, physical sources quite different from well-known quadratic magnetoelectric (ME) couplings. In systems with intrinsic...

On the basis of extensive experimental studies Pb${}_{1\ensuremath{-}x}$Ba${}_{x}$(Fe${}_{1/2}$Nb${}_{1/2}$)O${}_{3}$ (PFN-BFN) and Pb(Fe${}_{1/2}$Nb${}_{1/2}$)${}_{1\ensuremath{-}x}$Ti${}_{x}$O${}_{3}$ (PFN-PT) single crystals by several methods, we have proposed phase diagrams describing magnetic properties these solid solutions. The comprehensive consideration PFN-based solutions has shown that can be explained on a model suggested earlier for pure PFN [Phys. Rev. Lett. 105, 257202...

Using the Landau-Ginzburg-Devonshire theory, we considered impact of flexoelectrochemical coupling on size effects in polar properties and phase transitions thin ferroelectric films with a layer elastic defects. We investigated typical case, when defects fill below top film surface constant concentration creating an additional gradient fields. The defective is not covered electrode, but instead ultrathin ambient screening charges, characterized by length. Obtained results revealed...

Dielectric response of relaxor PMN single crystals was investigated in a broad frequency range 100 Hz–100 THz by combination dielectric spectroscopy (100 Hz–1 GHz, 10–700 K), time-domain and infrared (IR) reflectivity (5–3000 cm−1, 10–300 K). Polar TO1 phonon (soft mode) is resolved IR spectra at all temperatures studied, follows the Cochran law softens towards Burns temperature on heating. The central mode (dielectric relaxation) splits below room into two components. First one appears...

The general approach for the consideration of magnetoelectric effects in ferroic nanorods is proposed framework phenomenological theory. intrinsic surface stress, magneto- and electrostriction, as well piezoelectric piezomagnetic are included free energy. stress under curved nanoparticle shown to play an important role shift ferroelectric ferromagnetic transition temperatures appearance built-in magnetic electric fields, which inversely proportional nanorod radius. We consider case quadratic...

In the framework of thermodynamic approach Landau-Ginzburg-Devonshire (LGD) combined with equations electrostatics, we investigated effect polarization surface screening on finite size effects phase diagrams, polar, and dielectric properties ferroelectric nanoparticles different shapes. We obtained analyzed analytical results for dependences transition temperature, critical size, spontaneous polarization, coercive field shape nanoparticles. The pronounced these characteristics scaling...

The consideration of oxygen vacancies influence on the relaxors with perovskite structure was considered in framework Landau-Ginzburg-Devonshire phenomenological theory. theory applicability for is based existence some hidden soft phonon polar mode them, and its frequency could be zero at negative temperature TC*. Main attention paid to PZN-PLZT relaxor described by formula 0.3Pb(Zn1/3Nb2/3)O3-0.7(Pb0.96La0.04(ZrxTi1-x)0.99O3) x = 0.52, where earlier experimental investigation properties...

We explore the role of flexoelectric effect in functional properties nanoscale ferroelectric films with mixed electronic-ionic conductivity. Using a coupled Ginzburg-Landau model, we calculate spontaneous polarization, effective piezoresponse, elastic strain and compliance, carrier concentration, piezoconductance as function thickness applied pressure. In absence coupling, studied physical quantities manifest well-explored size-induced phase transitions, including transition to paraelectric...

We suggest an approach to calculate the physical properties of ferroelectric thin films. Our takes into account depolarization field and spatial inhomogeneity order parameter inherent In or approach, we consider film be short circuited with perfectly conducting electrodes monodomain. The solution corresponding Euler–Lagrange equation by direct variational method shows that initial free-energy functional a can reduced some effective which does not include derivatives parameter. coefficients...

The theory of size effects the properties nanocrystalline ferroelectric ceramic or nanoparticle powder allowing for surface tension and depolarization field is proposed. Surface was included into free energy functional expressed via coefficient. latter shown to be dependent on temperature due its relation dielectric permittivity nanoparticles. effect calculated in model taking account space charge layer surface, this space-charge being able compensate bulk material. Euler-Lagrange Equation...

We predict the conditions of superparaelectric phase appearance in ensemble noninteracting spherical ferroelectric nanoparticles. The superparaelectricity nanoparticles was defined by analogy with superparamagnetism, obtained earlier small made magnetic material. Calculations correlation radius, energetic barriers polarization reorientation, and response to external electric field, performed within Landau-Ginzburg phenomenological approach for perovskites...

Using electron spin resonance, lattice position and dynamic properties of Mn2+ ions were studied in 0.5 2 % manganese doped SrTiO3 ceramics prepared by conventional mixed oxide method. The measurements showed that substitute preferably up to 97 for Sr if the is with a deficit ions. Motional narrowing ESR spectrum was observed when temperature increases from 120 K 240-250 explained as manifestation off-center this ion at site. From analysis spectra activation energy Ea = 86 mV frequency...