0000000000020527
AUTHOR
A. I. Burkhanov
Structure and Lattice Dynamics in PLZT 8/65/35 Ceramics Irradiated by High-Current Pulsed Electron Beam
The comprehensive study of high-current pulsed electron irradiation effect on the structure and lattice dynamics as well as optical properties of PLZT 8/65/35 ceramics have been performed. X-ray powder diffraction studies shown the transformation of the rhombohedral perovskite structure R3m (Z = 1) into orthorhombic Pmmm (Z = 1) for the sample irradiated by one pulse (dose 4 × 1014 electrons/cm2) and, as a consequence, the changes in number of phonon modes position, oscillators strength and damping in IR and Raman spectroscopy data. However neutron powder diffraction measurements of multiple irradiated samples have not been revealed any structural distortions. Dielectric parameters have sho…
Bias Field Effect on Dielectric Response in the Region of Phase Transitions in (Pb,La)(Zr,Sn,Ti)O3Ceramics
The dielectric response of (Pb 0.97 La 0.02 ) (Zr 0.53 Ti 0.12 Sn 0.35 )O 3 (PLZTS-2/53/12/35) ceramics was measured as a function of DC bias field E =. As the bias field intensity increases the values of ϵ′ max and ϵ” max are found to shift towards a lower temperature. A possible coexistence of the ferroelectric and antiferroelectric phases over a wide range of temperatures in the PLZTS-2/53/12/35 samples is assumed to explain the observed features of ϵ′ (T), ϵ” (T), and ϵ′ (E=) curves.
Dielectric properties of Pb(Fe1/2Ta1/2)O3ceramics over 70–300 K temperature range
The studies of dielectric response in ferromagnetic lead ferrotantalate Pb(Fe1/2Ta1/2)O3 are reported over a wide range of temperature under the applied bias field. The features of dielectric nonlinearity deduced from behaviour of reverse e'(E=) curves at different temperatures, including regions of ferroelectric phase transition and vicinity of the Neel point, are examined. Obtained results indicate a substantial broadening of the ferroelectric phase transition. The results are discussed with respect to effects of ferroelectric ordering in relaxor materials of such kind.
Dielectric Properties of PbSc1/2Nb1/2O3-PbTiO3Ceramics
Lead titanate solid solutions exhibits extreme values of some physical parameters. We have investigated a ferroelectric relaxor ceramics of PSN-PT composition near the morphotropic phase boundary. Results are discussed with account for the relaxor properties related to defects and disordering of the PSN-PT system.
<title>Dielectric response to low and infra-low frequency in layered ferroelectrics</title>
Features of dielectric response to frequencies in the 0.25.1000 Hz range in ceramic samples of BaBi2Nb2O9, Na0,5Bi8.5Ti2Nb4O27, Na0,5Bi8.5Ti2Ta4O27, and K0,5Bi8.5Ti2Nb4O27 compounds are reported. Considerable relaxation of e'(T) and e"(T) maximums has been observed at all frequencies in BaBi2Nb2O9. Na0,5Bi8.5Ti2Nb4O27 and Na0,5Bi8.5Ti2Ta4O27 are characterised by broad maximums on e'(T) at frequencies below 100 Hz and a weak anomaly in K0,5Bi8.5Ti2Nb4O27 at temperatures well below the paraelectric phase transition. Increasing values of e' are observed at low temperatures in compounds containing sodium. The observed features of dielectric response are explained by largescale charge fluctuatio…
Polarization of SrBi 2 Ta 2 O 9 ceramics at infra‐low frequencies
Dielectric response in the SrBi2Ta2O9 ceramics is studied over a wide range of temperatures at fields up to Emax ≈ 18 kV/cm. Dependence of dielectric permittivity on field intensity is analyzed at different temperatures. A series of polarization loops are obtained at frequencies 0.1 Hz, 1 Hz, and 10 Hz. The hysteresis at switching polarization is displayed by the shape of polarization loops changing with the field amplitude from bi-angles to quasi-saturated loop patterns of a high degree of rectangularity. The ratio of remnant polarization to maximum polarization as function of field amplitude is presented. Thermal behaviour of the coercive field and the half-width of polarization loops is …
The Nature of Dielectric Nonlinearity in the Region of Diffused Phase Transition in Layered Ferroelectric BaBi2Nb2O9
By studying the dielectric properties of BaBi 2 Nb 2 O 9 ceramics, a representative of layered ferroelectrics, significant dispersion of ϵ* has been revealed at low- and infra-low frequences in the region of phase transition. Dispersion of ϵ* observed in “low-temperature” region (T T m where the basic contribution to ϵ* is provided by processes of the Maxwell-Wagner relaxation.
DIELECTRIC AGEING IN LAYERED FERROELECTRICS
ABSTRACT Studies of the effects of sample history on long-term relaxation of polarization in the Na0.5Bi8.5Ti2Nb4O27 and Na0.5Bi8.5Ti2Ta4O27 ferroelectrics of layered structures are reported. The type of functional relationship of e′(t) at measuring procedures including heating or cooling to the temperature being examined Ta is found to change from exponential (Kohlrausch function) to logarithmic. Results are discussed within the assumption of presence of defect complexes in disordered ferroelectrics.
Dependence of dielectric permittivity on bias field in Pb1−xBaxSc0.5Nb0.5O3
Abstract Bias field effect on the dielectric permittivity is studied in Badoped lead scandium niobate ferroelectric ceramics (PBSN-x) prepared by conventional technology. Results of this work allow to analyse the mechanism of possible formation and motion of domain and/or phase boundaries in the explored ferroelectric ceramics.
Dielectric Response in (K0.5Na0.5) (Nb1-xSbx)O3+0.5 mol%MnO2Ceramics to Weak Sinusoidal Fields of Low and Infra-low Frequencies
The thermal anomalies exhibited as “shoulders” at infra-low frequencies and maximums at low frequencies related to structural transitions in the polar phase of (K0.5Na0.5)(Nb1-xSbx)O3+0.5 mol%MnO2 are found to shift from T ∼ 185°C to T ∼ 140°C at changing concentration x from 0 to 0.05. The range of temperature ΔТ(х) corresponding to the difference between positions of the anomalies on the ϵ′(T) curve at frequencies 1000 Hz and 1 Hz changes from 0.5 degrees at x = 0 to 2.5 degrees at x = 0.05, which may point to relaxor properties of the given phase transition being present only at rather high concentrations of Sb.
<title>Dielectric polarization in <emph type="1">x</emph>PbZn<formula><inf><roman>1/3</roman></inf></formula>Nb<formula><inf><roman>2/3</roman></inf></formula>O<formula><inf><roman>3</roman></inf></formula>-(1-<emph type="1">x</emph>)PbSc<formula><inf><roman>1/2</roman></inf></formula>Nb<formula><inf><roman>1/2</roman></inf></formula>0<formula><inf><roman>3</roman></inf></formula> ferroelectric solid solutions</title>
Manifestation of relaxor properties in the x PbZn1/3Nb2/3O3-(1-x )PbSc1/2Nb1/203 ceramic solid solution system, similar to those observed in lead magnesium niobates, are reported. Dependence of the effective dielectric permittivity and dielectric loss on the temperature at frequencies of 0.1-10 Hz and different measuring field amplitudes E 0 are examined ceramic samples of 0.05PbZn1/3Nb2/3O3-0.95PbSc1/2Nb1/203. It is demonstrated that the temperature at which the dielectric permittivity has a maximum, T m, decreases with the increase of E 0. The dependence of T m on the frequency in both strong and weak fields is shown to follow the Vogel-Fulcher law, with Voger-Fulcher temperature decreasi…
Dielectric response of disordered BaBi2Nb2O9perovskite ceramics
Studies of dielectric properties of BaBi2Nb2O9 ceramics are reported. Considerable dispersion of ?* at low- and infra-low frequencies has been revealed in the region of the diffused phase transition. Dispersion of ?* is divided into ''low-temperature'' dispersion related to relaxation of polar formations and their boundaries and ''high-temperature'' dispersion (at T ? Tm) the main contribution to which comes from Maxwell-Wagner relaxation.
Reversive Dielectric Response in xPZN-(1 − x) PSN Ceramics
The effects of bias fields E= on dielectric response of xPbZn1/3Nb2/3O3-(1 − x)PbSc1/2 Nb1/2O3 ferroelectric solid solutions of x = 0, 0.05, 0.2, and 0.5 studied at temperatures of diffused phase transitions are reported. The thermal interval of the existence of a relaxor phase in the system is found to shrink with the concentration of PbZn1/3Nb2/3O3. The change of the ratio of zinc-lead and scandium-lead niobate components is deduced to change the features of the transition to polarised state from first-order to second-order transition.
The Effect of Bias Field on Dielectric Response in Lead Ferrotantalate Ceramics
Studies of dielectric properties of PbFe1/2Ta1/2O3 ceramics at low- and infra-low-frequencies under bias field over a wide range of temperatures are reported. Applied bias field is found to broaden the ϵ′(Т) maxima shifting positions Тm of the maximums to higher temperatures. Additional anomalies in the dielectric response are revealed at T<Тm. The anomalies in the vicinity of Тm are related to structural change at phase transition, while those observed at TТm – to magneto-electric interactions in PbFe1/2Ta1/2O3.
Effects of illumination on the dielectric response of barium-strontium niobate ceramics
A study of the effects of white light on the low and infra-low frequency relaxation of polarization in the barium-strontium niobate (SBN) ceramics is reported. The light is found considerably decreasing the contribution of space charge at temperatures corresponding to the range of the relaxor phase (it is, around the Tm).
Dielectric spectra of electron-irradiated PSN ceramics
The influence of electron-irradiation on the dielectric properties of transparent PSN ferroelectric ceramics is studied by low (LF) and infralow (ILF) frequency spectrum analysis. Redistribution of relaxation frequencies caused by electron-irradiation has been discovered and is related to pinning impacts of the radiation-induced defects.
Relaxation of polarization in (K0.5Na0.5)(Nb0.93Sb0.07)O3 ferroelectric ceramics modified by BaTiO3
ABSTRACTA study of low-frequency relaxation of polarization in conventionally prepared ceramic compounds of (1-x)(K0.5Na0.5)(Nb0.93Sb0.07)O3+xBaTiO3+0.5mol.%MnO2 (x = 0.02, 0.04) examined over a wide temperature range is reported. Anomalous behavior of the temperature dependence of the coercive field Ec(T) is detected in the temperature range of the orthorhombic to tetragonal phase transition. The observed features of polarization are assigned to dynamics of the domain structure at the temperature range of phase coexistence.
The effect of bias field on the dielectric response of Ba0.95Pb0.05TiO3+Со2О3
The nature of the dielectric response in ferroelectric ceramics Ba0.95Pb0.05TiO3+Со2О3 (BPTC) under the influence of a constant bias field EB in the phase transition region is studied. It is found ...
Depolarization Currents and Ageing in Layered Na0.5Bi8.5Ti2Nb4O27and Na0.5Bi8.5Ti2Ta4O27Ferroelectrics
The present study is focused on the behaviour of polarization and depolarization currents and processes of the slow relaxation of polarization within the range of temperatures where the anomalies are displayed by the materials. Results of the study are discussed with regard to possible existence of defect complexes in disordered ferroelectrics.
Dielectric Properties of PMN-PNN+2%Li2O Ferroelectric Ceramics at Low and Infra-Low Frequencies
AbstractA study of dielectric response to weak and strong measuring fields at temperatures of the diffuse phase transition in lead-magnesium niobate—lead-nickel niobate (PMN-PNN) containing an admixture of lithium is reported. A relaxor behaviour of the ceramic compound manifesting itself by a substantial shift of the temperature of dielectric permittivity maximum with field intensity and frequency is detected. Specific features of the dielectric nonlinearity observed at temperatures considerably higher than the temperature of the low-frequency dielectric permittivity maximum are related to extension of the range of phase transition to higher temperatures. This extension is related to forma…
Dielectric and acoustic properties of modified barium titanate ceramics
This work was supported in part by the Ministry of Education and Science of the Russian Federation.
Low frequency nonlinearity in layered ferroelectrics BaBi<inf>2</inf>Nb<inf>2</inf>O<inf>9</inf> and SrBi<inf>2</inf>Ta<inf>2</inf>O<inf>9</inf>
The dielectric nonlinearity in layered ferroelectric ceramics of BaBi 2 Nb 2 O 9 and SrBi 2 Ta 2 O 9 is studied by analysing polarisation loops and measuring dielectric permittivity as a function of frequency. In case of BaBi 2 Nb 2 O 9 the system has a broad phase transition manifesting essential features of a slow relaxation of polarisation; in case of SrBi 2 Ta 2 O 9 the processes contributing to polarisation switching are driven by rearrangement of the domain structure.
Dielectric Properties of the 0.05PZN–0.95PSN Ferroelectric Ceramics at Low and Infra-Low Frequencies
Manifestations of relaxor properties similar to those observed in lead magnesium niobates are reported in the 0.05PZN–0.95PSN ceramic solid solution system. Behaviour of the effective dielectric permittivity and dielectric loss with temperature at frequencies between 0.1 and 10 Hz at different field amplitudes are examined in ceramic samples of 0.05PZN–0.95PSN. The temperature T m of the dielectric permittivity maximum is observed to decrease with the increase of the measuring field amplitude E o . Dependence of T m on frequency at strong and weak fields is observed to follow the Fogel-Fulcher law, and the Fogel-Fulcher temperature is found to decrease with the increase of E o . Results of …
Dielectric properties of potassium–sodium niobate ceramics at low frequencies
ABSTRACTA study of the effects of ageing history on the electrical properties of lead-free ferroelectric ceramics of (K0.5Na0.5)(Nb1−xSbx)O3 + 0.5 mol% MnO2 and (K0.5Na0.5)(Nb1−xTax)O3 + 0.5 mol%MnO2 for x = 0.05 is reported. The samples after storage at a constant temperature have been subject to infra-low-frequency electric field and radiation. Differences of the photoelectric response between the two examined compounds were found and the restoration of polarisation in the aged ceramic materials by cycles of applied field is discussed.
Photoelectric Current and Dielectric Properties of Barium-Strontium Niobate Ceramics under UV and Visible Irradiation
A study of photocurrent kinetics and dielectric response to infra-low frequencies in the range of the broad phase transition in the Ba0.25Sr0.75Nb2O6 (BSN-75) relaxor ceramics under visible and ultraviolet radiation is reported. Anomalies are revealed in the dependence on field intensity of dielectric permittivity and dielectric loss determined from measurements of polarisation loops before and after illumination. The effects of pyro-electric space charge, polarisation and photovoltaic contributions on behaviour of the measured photocurrent are discussed. Results of the kinetics of photocurrent and dielectric response to infra-low frequency studied at different temperatures are discussed as…
Relaxor Properties of Barium-Strontium Niobate Ceramics
Dielectric properties of Sr0.75Ba0.25Nb2O6 (SBN-75) ceramics in the range of low and infra-low frequencies are reported. The values of ϵ′ and, in particular of ϵ″, in ceramics are found to be much smaller compared with SBN-75 single crystals below the temperature (Тm) of the ϵ′(T) maximum a sharp increase of the values of dielectric parameters observed above Тm being also different from their thermal behaviour in single crystals. The broadening of phase transition and dependence of the response on sample history are similar to the features observed in other relaxor materials.
Dielectric properties of PMN+2%Li 2 O at low frequencies
The reported study is focused on effects of the admixture of lithium (2% Li2O) on the low-frequency dielectric response in lead magnesium niobate ceramics over the 100 -300 K range of temperature. The obtained results reveal an essential thermal broadening of the e′(ν) spectra specific to relaxor ferroelectrics. Dispersion Δe′ = e′1Hz-e′1kHz and values of e′′(ν) in lead magnesium niobate ceramics containing Li are well described by the Cole-Cole equation at temperatures below the e′(T) maximum. Based on the analysis of the experimental data admixture of lithium is suggested to promote formation of domains in lead magnesium niobate ceramics (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Dielectric memory effects of (Mn, Fe, Co, Cu, Eu) doped PLZT ceramics
Abstract Dielectric memory effects—effect of thermal memory (ETM) and effect of electric field memory (EFM) have been studied in (Mn, Fe, Co, Cu, Eu) doped PLZT ceramics. The obtained results have been discussed on the assumption that the ETM and EFM depends on relaxation of domain and interphase (polar and nonpolar) boundaries influenced by changes of defects conditions at doping.
Kinetics of dielectric response in SBN-75 ceramics at infra-low frequencies under illumination
A study of the photo-dielectric effect in ferroelectric SBN-75 ceramics of a broad phase transition under light of small intensity is reported. Relations determining kinetics of the infra-low frequency dielectric response under light and after illumination are obtained from experimental measurements revealing the features of the behaviour of relaxation time constants of the dielectric polarisation with temperature.
Relaxation of Polarization at the Broad Phase Transition in Modified PMN Ferroelectric Ceramics
The reported study is focused on effects of relaxation of polarization within the range of the broad phase transition at strong sinusoidal measuring fields in modified lead magnesium niobate ceramics. The obtained results reveal an essential thermal broadening of the ϵ′(E) spectra specific to relaxor ferroelectrics. Temperature dependence of ϵ′ eff (T) at medium fields shows two broad maximums – at Tm and at 40°C. On the basis of analysis of the experimental data, admixture of lithium is suggested to promote formation of domains in lead magnesium niobate ceramics.
ELECTRICAL PROPERTIES OF LEAD FERROTANTALATE CERAMICS
ABSTRACT Perovskite structures with high dielectric constants and magnetic properties play an important role in micro- and optoelectronics and have numerous practical applications. Relaxor type ferroelectric ceramics PbFe1/2Ta1/2O3 with perovskite structure was subject of present studies. Pyrochlore free lead ferrotantalate ceramics were produced by solid state technology from oxides. Low- and infra-low frequency studies of dielectric properties of PbFe1/2Ta1/2O3 ceramics have revealed considerable infra-low frequency dispersion at temperatures above the temperature of maximum dielectric permittivity. The observed dispersion described by lemniscates is due to a considerable Maxwell-Wagner r…
Photoelectrical Properties of the SBN Relaxor Ceramics in the Range of the Broad Phase Transition
AbstractA study of the effects of white light on photocurrent kinetics and the low and infra-low frequency relaxation of polarization in the barium-strontium niobate SBN‑75 ceramics is reported. It is found that at a low intensity illumination in the range of the relaxor phase the space charge is mainly responsible for manifestation of photo-electrical properties of SBN-75 ceramics.