Yu. N. Zakharov

Critical nature of the giant field-induced pyroelectric response in Pb(Mg1/3Nb2/3)O3–xPbTiO3 single crystals

We study the E-T phase diagram and dynamical pyroelectric coefficient of an (001)-oriented flux-grown 0.8Pb(Mg1/3Nb2/3)O3–0.2PbTiO3 single crystal. We found that the highest pyroelectric coefficient can be achieved at the point having quasicritical features. These data establish a quasicritical behavior of the field-induced pyroelectric coefficients in relaxors.

Field-Induced Enhancement of Pyroelectric Response of PbMg1/3Nb2/3O3-PbTiO3 and PbFe1/2Nb1/2O3-PbTiO3 Solid Solution Ceramics

A dramatic influence of bias field on pyroelectric response was revealed for ceramics of (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 with x = 0.075, 0.33 and 0.98Pb(Fe1/2Nb1/2) O3–0.02PbTiO3. Temperature and bias field dependency of the dielectric permittivity and dynamic pyroelectric coefficient have been studied to establish possible relation of the enhanced pyroelectric activity with the E-T phase diagram. In relaxor ceramic composition PMN-0.075 the highest pyroelectric coefficient was achieved at the point having quasi-critical features. These data support an assumption of quasi-critical behavior of the pyroelectric response in relaxor ceramics, in accord with our previous data for relaxor single crystals.

Bias Field Effect on the Dielectric and Pyroelectric Response of Pb(Fe0.5Ta0.5)O3 Relaxor Multiferroic Ceramics

Dielectric and pyroelectric studies of PbFe0.5Ta0.5O3 ceramics have been carried out under different bias field values. E,T-phase diagram has been constructed using these data. It has been found out that PbFe0.5Ta0.5O3 combines the properties of both relaxors and usual ferroelectrics. The results obtained show that the origin of the relaxor-like behavior in PbFe0.5Ta0.5O3 seems to be somewhat different as compared to canonical relaxors.

Bias Field Effect on the Dielectric and Pyroelectric Response of Single Crystal of Uniaxial Relaxor Sr0.75Ba0.25Nb2O6

Dielectric and pyroelectric studies of lead-free uniaxial relaxor Sr0.75Ba0.25Nb2O6 (SBN75) single crystals have been carried out under different bias field values. E,T-phase diagram has been constructed using these data. Dependences of both the temperature and the height of dielectric permittivity and pyroelectric coefficient maxima on the bias field are similar to those observed previously for PbMg1/3Nb2/3O3 - PbTiO3 crystals and support the presence of the critical endpoint in the E,T-phase diagram of SBN75 and a critical behavior of field-induced pyroelectric response in uniaxial relaxors.

Bias Field Effect on Dielectric and Pyroelectric Properties of (1-x)Pb(Fe1/2Nb1/2)O3–xPbTiO3 Ceramics

Dielectric, X-ray, pyroelectric and piezoelectric studies of the (1-x)PbFe1/2Nb1/2O3–(x)PbTiO3 ceramics from the 0 ≤ x ≤ 0.2 range fabricated by solid state synthesis and usual sintering have been carried out. In PbFe1/2Nb1/2O3 and compositions with low Ti content anomalies of dielectric, pyroelectric and piezoelectric parameters, corresponding to the transition between two ferroelectric phases have been observed at 85–90°C. A dramatic effect of bias field on dielectric and pyroelectric responces was revealed.

Pyroelectric properties of the multi-component ferroelectric ceramic materials

Abstract Five-component ferroelectric ceramic materials, on the basis of solid solutions of: PbTiO 3 –PbZrO 3 –PbNb 2/3 Zn 1/3 O 3 –PbSb 2/3 Mn 1/3 O 3 –PbW 1/2 Mg 1/2 O 3 (system I) and PbTiO 3 –PbZrO 3 –PbNb 2/3 Zn 1/3 O 3 –PbSb 2/3 Mn 1/3 O 3 –PbNb 2/3 Mn 1/3 O 3 (system II), have been prepared by means of hot pressing technique. The pyroelectric properties of the above mentioned ceramic materials were investigated at room temperature for compositions from both tetragonal and rhombohedral phase areas, as well as from the morphotropic phase boundary region. The dependence of the pyroelectric coefficient on the concentration of PbTiO 3 is shown. Enhanced pyroelectric activity of the systems under investigation was found. The pyroelectric coefficient for the compositions from the morphotropic region worked out at γ 1 =4×10 −4 Cm −2 K and γ 2 =5×10 4 Cm −2 K for the system I and II, respectively. It was stated that the materials under investigation were characterised by high merit numbers, which made them prospective for pyroelectric detectors.

“Controlled” surface layers in BaTiO3 single crystals

In spite of the fact that the existence of surface layers in ferroelectric materials has been verified by numerous experiments, their physical nature still remains obscure.1

E-T phase diagrams of a solid solution of the multicomponent PbZn1/3Nb2/3O3-PbMg1/3Nb2/3O3-PbNi1/3Nb2/3O3-PbTiO3 system near the morphotropic phase boundary

The specific features of the dielectric and pyroelectric responses of a solid solution in the barium-doped multicomponent yPbZn1/3Nb2/3O3-mPbMg1/3Nb2/3O3-nPbNi1/3Nb2/3O3-xPbTiO3 system of the composition y = 0.0982, m = 0.4541, n = 0.1477, and x = 0.3 near the morphotropic phase boundary have been investigated. It has been assumed that the maxima revealed in the dependences of the reversible permittivity on the electric field strength with both the forward and backward changes in the field (E=) are associated with the induced phase transition. Based on the experimental results, the E-T phase diagrams are constructed in the temperature range from −100 to 150°C for different temperature-field regimes: (i) variation in the electric field E= at a fixed temperature of the sample and (ii) variation in the temperature of the sample at a constant value of E=. It has been found that there is a singular point in the E-T phase diagram and that, in the vicinity of this point, the dielectric and pyroelectric responses of the studied ceramics exhibit specific features.

Piezoelectric Properties of PbFe1/2Nb1/2O3–PbTiO3 Ceramics from the Morphotropic Phase Boundary Compositional Range

Dielectric, X-ray, and piezoelectric studies of highly-resistive Li-doped (1-x)PbFe1/2Nb1/2O3–(x)PbTiO3 (PFN-xPT) ceramics from the 0 ≤ x ≤ 0.2 range fabricated by solid state synthesis and usual sintering have been carried out. Distinct anomalies of dielectric and piezoelectric parameters, corresponding to the transition between rhombohedral (monoclinic) and tetragonal ferroelectric phases have been observed in pure PbFe1/2Nb1/2O3 and PFN-xPT compositions with PbTiO3 content up to 8 mol.%. x,T-phase diagram of the PFN-xPT solid solution system have been constructed using these data.

Dependences of the dielectric and pyroelectric properties of (1 − x)PbFe1/2Nb1/2O3−xPbTiO3 ferroelectric ceramics solid solutions on the PbTiO3 content in a compositional range of 0 ≤ x ≤ 0.08

Abstract(1 − x)PbFe1/2Nb1/2O3−xPbTiO3 (PFN-xPT) ferroelectric ceramics with low dielectric loss and pronounced anomalies of dielectric and pyroelectric properties near the ferroelectric-ferroelectric phase transition was obtained by doping with lithium. The temperature dependence of the position of the morphotropic boundary between the rhombohedral (monoclinic) and tetragonal phases in the x-T phase diagram of the PFN-xPT system was determined for the first time.