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Details of local atomic structure and dynamics play a significant role in determining the ferroelectricproperties, even though ferroelectricity is a highly collective phenomenon. They are most importantin disordered ferroelectrics, the relaxor ferroelectrics in particular. In this chapter we discuss howneutron scattering measurements enable us to see directly the local structure and dynamics and facilitatethe...
In this article La and Nb co-substitution effect on the crystal structure, microstructure, ferroelectric and dielectric properties of 0.96[{Bi0.5 (Na0.84 K0.16)0.5}1−xLax(Ti1−y Nby)O3]-0.04SrTiO3 (BNKLTN-ST, where (x=y) = 0.00 − 0.020) ceramics has been investigated. The ceramics with x,y ≤ 0.010 have pure perovskite structure, while a secondary phase appears in the sample with x=y = 0.020. X-ray...
A novel 1-1-3 type composite is proposed to increase the electromechanical coupling coefficient. Relaxor ferroelectric single crystal is cut into columns and surrounded by soft polymer. The other kind of hard polymer is manufactured to form a 3D grid structure. The relaxor ferroelectric single crystal and soft polymer are located in lattice of the hard polymer. The single crystal and soft polymer...
In the present work we investigate the influence of acceptor (K+, Cu+, Li+), donor (La3+, Bi3+, Eu3+, Nd3+, Y3+, Cr3+) and charge equivalent dopants (Sr2+, Co2+, Mn2+, Ta5+) on the dielectric and ferroelectric behavior of 0.92 Pb(Mg1/3Nb2/3)O3-0.08 PbTiO3(0.92PMN-0.08PT). As a criterion for the basic suitability for electrocaloric cooling application, we directly measure the temperature change (ΔT)...
In the present work we investigate the influence of acceptor (K+, Cu+, Li+), donor (La3+, Bi3+, Eu3+, Nd3+, Y3+, Cr3+) and charge equivalent dopants (Sr2+, Co2+, Mn2+, Ta5+) on the dielectric and ferroelectric behavior of 0.92 Pb(Mg1/3Nb2/3)O3-0.08 PbTiO3(0.92PMN-0.08PT). As a criterion for the basic suitability for electrocaloric cooling application, we directly measure the temperature change (ΔT)...
The longitudinal acoustic wave velocity and attenuation in PbFe1/2Ta1/2O3 and BiFeO3 ceramics have been measured by ultrasonic pulse-echo technique in the temperature range from 50 K to 530 K and from 250 K to 830K, respectively. The anomalies observed in the sound velocity behavior versus temperature in the case of PbFe1/2Ta1/2O3 were correlated with Burns temperature and temperature range of relaxor...
We combine high-pressure x-ray diffraction, high-pressure Raman scattering, and optical microscopic methods to investigate a series of PMN-xPT solid solutions (x=0.2, 0.3, 0.33, 0.35, 0.37, 0.4) in diamond anvil cells up to 20 GPa at 300 K. The Raman spectra show a new peak centered at 380 cm−1 above 6 GPa for all samples, consistent with previous observations. X-ray diffraction measurements are consistent...
Acoustic vector hydrophone is an underwater sound receiver, which can measure particle velocity, particle acceleration and pressure gradient. By using double flexural vibration disks as the driving element, a pressure gradient hydrophone of Cymbal structure is proposed. The dipolar mode of the Cymbal hydrophone can be excited by the vibration of the flexural disk and the dipolar directivity pattern...
Stability and crystalline quality of PMN-PT (65/35) thin films deposited by Pulsed Laser Deposition on MgO <;001>; and MgO <;111>; are studied by X-Ray diffraction and Raman Scattering Spectroscopy. From these investigations, the stabilization of PMN-PT films on <;111>; Pt-coated silicon substrate is obtained by the integration of an oxide layer (La0.66Sr0.33MnO3) on the Pt surface...
The critical behavior of a relaxor ferroelectric 0.7Pb(Sc1/2Nb1/2)O3-0.3PbTiO3 (PSN-0.3PT) crystal is studied by the broadband micro-Brillouin scattering. Remarkable and continuous elastic anomaly is observed in the vicinity of the Curie temperature TC=500 K. The integrate intensity of a central peak obeys the Curie-Weiss law. The relaxation length of strain fluctuations on nanometer scale, l =VτCP...
In mixed perovskite-oxides with displacive type phase transition, the phenomenological theory is tried to make clear the conditions for relaxor appearance, and is extended to combine with a microscopic approach in order-disorder type transition. Relaxor region near the morphotropic phase boundary (MPB) is lead depending on the anisotropy of polarization, and under conditions similar to those for relaxor...
A number of Pb-free BaTiO3 - Bi(Zn1/2Ti1/2)O3 solid solutions have been studied by Huang et al.. Compositions close to 0.8BaTiO3 - 0.2Bi(Zn1/2Ti1/2)O3 revealed pseudo-cubic symmetry and showed a linear dielectric response. The existence of a nearly flat temperature dependence of the relative permittivity over the temperature range of 100°C to 350°C was also obtained. In this study, the effects of...
High permittivity dielectrics ceramics are often used for commercial multilayer ceramic capacitors, actuators applications, and is highly promising materials for dynamic random access memory (DRAM) and microelectromechanical systems (MEMS) applications due to its very stable, high insulating characteristic against voltage. Many studies have been conducted to enhance the above mentioned properties...
Experimental data on the nonlinear dynamic responses of barium titanate (discontinuous phase transition, PT), triglycine sulphate (continuous PT), as well as the prototype relaxor lead magnoniobate, and the weakly doped quantum paraelectric K0.995Li0.005TaO3 are presented. The classic ferro-electrics display all features of the third-order dielectric susceptibility, X3, as predicted by mean-field...
In this paper, piezoelectric and relaxor ceramics are the basic materials that are used in designing sensors. The project concentrates on the study and characterization of ceramic materials on the basis of d33, g33 and dielectric constant values. PZT (Pb (Zr0.55Ti0.45)O3), which belongs to the oxygen octahedral group, exhibits perovskite structure. PZT crystallites are centra-symmetric cubic (isotropic)...
A series of relaxor piezoelectric single crystals, including lead magnesium niobate-lead titanate (PMN-PT) and pure and manganese-doped lead indium niobate-lead magnesium niobate-lead titanate (PIN-PMN-PT and Mn: PIN-PMN-PT), have been developed by a modified Bridgman crystal growth process. These single crystals have been grown along both <001> and <110> with diameters up to 75 mm. PIN-PMN-PT...
Polycrystalline sample of Ba4Gd2Fe2Nb8O30 ceramics were prepared by a high temperature solid-state reaction technique. The structure and dielectric properties as well as the behavior of ferroelectric phase transition have been investigated. The dielectric spectra are characterized in wide frequency (40 Hz-1 MHz) and temperature (25degC-600degC). At 1MHz, the room temperature dielectric constant of...
Lanthanum doped lead zirconate titanate [(Pb,La)(Zr,Ti)O3] transparent ceramics show relaxor behavior when the content of Lanthanum is 4-14% and molar ratio of Zr/Ti is 65/35. They were known as important electro-optical materials, but few researches had been focused on their electromechanical behavior. In the present work, we report a large recoverable electrostrain of about 0.2% at 1.0 kV/mm in...
Relaxor-PT single crystals are at the forefront of advanced transducer applications, including medical ultrasound and high power sonar. In this work, we report on recent developments in Relaxor-PT crystals, specifically increased temperature usage and crystallographic and domain engineering relationships. Furthermore, we contrast developments in crystals with respect to both ldquosoftrdquo and ldquohardrdquo...
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