Search results for "ferroelectric"
showing 10 items of 374 documents
Some nonlinear properties of ferroelectric smart materials
2001
Four types of nonlinear properties of ferroelectric smart materials have been considered: nonlinear dynamics of the paraelectric–ferroelectric interphase boundaries, nonlinear equilibrium excitations}domain walls, nonlinear response of the domain structure near the first-order phase transition}wetting of domain walls}andnonlinear effects causedby external high magnetic fields. The above mentioned nonlinearities have been studied in ðBa; SrÞTiO3ðBSTÞ and PbðZr; TiÞO3ðPZTÞ. # 2001 Elsevier Science B.V. All rights reserved.
PHASE TRANSITIONS IN Na1/2Bi1/2TiO3-SrTiO3-PbTiO3 SOLID SOLUTIONS
2009
ABSTRACT Studies of nature of polarization in ternary solid solutions of Na1/2Bi1/2TiO3-SrTiO3-PbTiO3 were done, using measurements of dielectric properties and polarization hysteresis loops. Various stages of relaxor behavior depending on concentration of PbTiO3 were established and compared with other known ferroelectric relaxors.
Dielectric Properties and Conductivity of Ferroelectric LixNa1-xTa 0.1Nb0.9O3 Solid Solutions
2011
Results of a study of dielectric properties and conductivity of ferroelectric perovskite solid solutions of the LixNa1-xTa0.1Nb0.9O3 (х = 0.03–0.135) series with the 290–700 K thermal range and frequencies from 25 to 106 Hz are reported. The charge in this kind of materials is shown to be transferred by Li+ ions the contribution from bulk transport of ions dominating. A first order phase transition close to the second order transitions proceeds in LixNa1-xTa0.1Nb0.9O3 solid solutions within the thermal range examined. The increase of Li concentration enhances the features of the second order transition.
Study of the spontaneous relaxor to normal ferroelectric phase transition in la-doped lead titanate
2000
Abstract Highly lanthanum doped lead titanate ceramics exhibit relaxor properties and undergo on cooling a subsequent spontaneous macroscopic phase transition. The dielectric response is strongly affected by chemical (copper) doping and is found to become independent of the applied ac field for temperatures lower than the phase transition one.
Phase transitions and properties of perovskite ferroelectric ceramics and films for certain applications
1999
Abstract The structure-properties relationships and phase transitions in perovskite ceramics, and films of PLZT, PLZST, PST, PSN, PMNT compounds are discussed with regard to ordering, relaxor behaviour, pronounced ferroelectric, electromechanical and electrocaloric properties. The theoretical approach is extended to the time dependent Ginsburg-Landau model. The evolution of dielectric properties in relaxors after the change of temperature and electric field creating an increase of dielectric permittivity is found to follow a logarithmic law of decay. A strong electromechanical response is observed in a number of thin films of different compositions.
Relaxation of Polarization at the Broad Phase Transition in Modified PMN Ferroelectric Ceramics
2013
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.
Dielectric Properties of PMN-PNN+2%Li2O Ferroelectric Ceramics at Low and Infra-Low Frequencies
2014
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 properties of Pb(Fe1/2Ta1/2)O3ceramics over 70–300 K temperature range
2011
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.
Reversive Dielectric Response in xPZN-(1 − x) PSN Ceramics
2006
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.