S. I. Dudkina

Preisach model and simulation of the converse piezoelectric coefficient in ferroelectric ceramics

The electric-field dependencies of the elastic strains ξ3(E) and the converse piezoelectric coefficients d33(E) for ferroelectric ceramics of different degree of ferroelectric hardness have been measured. The observed results have been approximated by the Preisach and Rayleigh polynomials. The nonmonotonic d33(E) dependence for ferroelectric ceramics has been established. The interpretation of the observed results based on a substantially different distribution of reoriented domains over the internal and coercive electric fields in the ceramics of different degree of ferroelectric hardness is given.

Correlation between the microstructure of ferroelectric ceramics and their chemical and phase composition, the degree of perfection of the crystal structure and the preparation conditions

The correlation between crystallite sizes of ferroelectric ceramics and spontaneous deformation of the crystal unit cell was considered for two cases: 1) in varying concentrations of solid solutions of the systems based on NaNbO3 and PbTiO3-PbZrO3, and 2) in the individual compositions of the above systems with the crystallite size varying with the preparation conditions. It is shown that in the first case there is a reciprocal dependence between the homogeneous deformation parameter Δ characterizing the spontaneous deformation of the crystal unit cell and the crystallite sizes d. In the second case Δ varies with d.

Phase diagrams and ferroelectric properties of solid solutions of the ternary systems (Na, Li, Cd0.5)NbO3 AND (Na, Li, Sr0.5)NbO3

Some precision X-ray studies of solid solutions of the ternary systems (Na, Li, Cd0.5)NbO3 and (Na, Li, Sr0.5)NbO3 were carried out, which enabled one to determine more accurately the symmetry of crystallizing phases, structural transitions and the morphology of morphotropic regions. Concentration dependences of electrophysical characteristics of solid solutions of these systems were studied and their relation with structural parameters was revealed.

Ferroelectric solid solutions with high piezoelectric characteristics

Abstract It has been shown that high dielectric permittivity and piezoelectric parameters are obtainable within the PZT-related multicomponent solid-solution systems by appropriate choice of the cationic constitution, component number and concentration ranges. The role of grain size has been emphasized.

Electromechanical Switching Processes in Ferroelectrics-Ferroelastics: Theory and Experiment

Electric field dependences of the elastic strains and converse piezoelectric coefficients for some soft and hard ferroelectric ceramics were measured. The observed results were approximated by the Preisach and Rayleigh polynomials. The experimental data testify to the inequality of direct, converse and dynamical piezoelectric coefficients for all the ferroelectric ceramics under study that is a result of the presence of domain structure and its contribution to the piezoelectric properties of ceramic ferroelectrics.

Interdependences among crystallochemical, structural and electrophysical parameters of ferroelectric solid solutions

Abstract In multicomponent systems of the PbB1-αB”αO3 complex oxides based on Pb(Zr,Ti)O3, strict linear dependence has been revealed of the spontaneous deformation of the tetragonal cell on the total electronegativity of the elements B, Ti, and Zr. Quantitative relationships have been defined between electrophysical and structural parameters of the solid solutions permitting their properties to be predicted.

Properties of multicomponent solid solutions based on lead zirconate titanate near morphotropic regions

The structural and dielectric (εT33/ε0) properties of Pb(Ti,Zr)O3–PbB1-αBαO3–PbB1-βBβO3solid solutions were studied along the morphotropic region. Depending on the nature of the substituent cations, the properties of the solid solutions either vary monotonically with the content of the soft-electric component or exhibit extrema at a certain average electronegativity of the B-site cations.

Dielectric Properties of Pb(Ti,Zr)O3–∑n=14 (PbB"1-αB""αO3)nSolid Solutions

Dielectric permittivity measurements in Pb(Ti,Zr)O3–∑n=14 (PbB1 - αBαO3)nsolid-solution systems demonstrate that the permittivity εT33/ε0of the solid solutions correlates with the molar ratio of the more soft-electric to the less soft-electric component of PbB1 - αBαO3(γ). With increasing γ, εT33/ε0rises because of the decrease in the uniform cell distortion parameter. The permittivity is also sensitive to structural disordering at γ > 1 and reduction in the density of the materials at γ ≫ 1.

Ferroelectric Elastance of Sodium Niobate-Lithium Niobate Solid Solutions in Relation to A -O Bond Covalence

The ferroelectric elastance of (Na, Li, A0.5′)NbO3 solid solutions was found to vary directly with the total electronegativity of elements A (EN∑A), that is, with the A-O bond covalence at B=const. Using EN∑A values and the position on the phase diagram, one can determine the solid solution parameters optimum for use in high-frequency (A′=Sr, Pb), medium-frequency (A′=Cd), and elevated-temperature (A′=Cd) devices.

The effect of space charge and crystallite size on the formation of properties of ferropiezoceramic materials

The effect is treated of the space charge field and of the crystallite size on the properties of ferroceramics of different compositions. The established qualitative correlation between the structure and electrophysical parameters, the crystallite size, and the space charge field may be useful in designing ferropiezoceramic materials for different applications and devices involving such materials.