V. A. Servuli

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 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.

A spread in electrophysical parameters of ferroelectric piezoelectric solid solutions and its minimization

A spread in electrophysical parameters of solid solutions based on PZT and niobium oxides is considered for a wide range of component concentration. It is shown that composition fluctuations and their associated solution imperfection cause a significant deviation of the parameters from their mean values. The fluctuations are most pronounced when the crystal structure is unstable (e.g., at morphotropic transitions and near the solubility limits of the components). The optimization of methods for solid solution preparation greatly reduces the effect of process variables on parameter reproducibility.

High-stability ferro- and piezoelectric solid solutions of multicomponent systems of complex oxides

Abstract High anisotropy in elastic characteristics CD 33/CE 44 together with high-temperature stability of resonance frequency over a wide temperature range are required in piezoelectric ceramic materials for high-frequency (HF) filters in a monolithic version. The increased values of CD 33/CE 44 may be obtained by de-creasing the value of CE 44, that is, by decreasing the ferroelectric hardness of a solid solution (high-stability solid solutions usually have the high degree of ferroelectric hardness). In the solid solutions under study the value of CD 33 varies negligibly and, therefore, the solid solutions with middle ferroelectric hardness were used to prepare these materials.

X-ray amd electrophisical studies of anisotropic PbTiO3-based piezoelectric ceramics

Abstract A study of structural, electrophysical and strength, parameters of anisotropic piezoelectric ceramics PCR-70 was carried out over a wide range of sintering temperatures and polarizing fields. The character of correlation between these parameters was established and described.

Phase diagram and physical properties of the sodium niobate-lithium niobate-cadmium niobate three-component system

The phase diagram of the (Na,Li,Cd0.5)NbO3 ternary system is refined. The electrical properties of solid solutions over a broad range of the component concentrations were studied. The compositions promising for high-temperature transducers were obtained.

Phase transitions and electrical properties of solid solutions of sodium, lithium, and strontium niobates

An additional study of solid solutions in the (Na, Li, Sr0.5)NbO3 ternary system was performed. More detailed information concerning its phase diagram and physical parameters in a wide range of component concentrations is obtained. The compositions obtained are of interest for application in highly sensitive and high-frequency transducers.

Correlation between piezoelectric and electee properties of the PZT ceramics

Abstract The correlation between piezoelectric and electret properties of ceramic solid solutions with the composition xPbTiO3-(0.98-x)PbZrO3-0.02PbW0.5Cd0.5O3 for 0.445≤x≤0.610 polarized in the negative corona discharge was studied. The maximum piezoelectric constants and time constant of electret charge decay at x=0.475 may be explained by the combination of high values of remanent polarization and small unit-cell deformation ensuring the low relaxation velocity of remanent polarization and a screening homocharge.

Examination of the effect of the polarizing field on the mechanical strength of anisotropic piezoceramics based on PbTiO3

Results are presented of examination of the effect of a constant polarizing field of the mechanical strength of PKR-67 anisotropic piezoceramic material developed at the Scientific Research Institute of Physics at the Rostov State University. The strength of disk piezoelements in tensile loading was evaluated by the coaxial bending method. An increase of the strength of the constant polarizing field resulted in a nonmonotonic reduction of the mechanical strength limit. This variation of the mechanical strength limit is determined by the nonstationary nature of the processes of formation and growth of microcracks as a result of interaction of these microcracks with the rearranged domain structure and defects. In the field strength range Ep=(6–8)·106 V·m−1 it was possible to produce sufficiently strong piezoceramics with unique combination of the main electrophysical parameters.