Papers by Keyword: Relaxor

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Authors: Paweł Wawrzała, Dariusz Bochenek
Abstract: This paper presents a new way of using the classical Preisach distribution to the analytical description of the behavior of ceramic ferroelectrics in a wide range of temperatures. The iteration method have been used to investigate the Preisach distribution from polarization-electric field hysteresis loops to observe the composition and temperature variation of the some parameters in lead barium zirconate titanate stannate ceramic samples. Received Preisach distributions from P-E hysteresis loops were modeled by selected analytical functions to find useful parameters to observing the evolution of the hysteresis loops with temperature. This type of analysis can allow a more complete understanding of the relaxor properties occurring in these kind of materials, and may be used to examination the changes of temperature changes of piezoelectric sensors.
Authors: Juras Banys, Jan Macutkevic, Algirdas Brilingas, Vytautas Samulionis, K. Bormanis, Andris Sternberg, Vismantas Zauls
Abstract: Dielectric properties of 0.4PbZn1/3Nb2/3O3-0.3PbSc1/2Nb1/2O3-0.3PbMg1/3Nb2/3O3- (0.4PZN- 0.3PSN-0.3PMN) ceramics are presented for 200 < T < 500 K and 20 Hz < ν < 1 MHz. Dielectric constant is very high (more 14000) in the vicinity of the peak. Anomalous broad dielectric relaxation have been observed near the temperature of the maximum permittivity, Tm (at 1 kHz). External bias field considerably lowers the value of dielectric losses at low frequencies due to decrease of polar nano regions contribution to the dielectric permittivity.
Authors: Wolfgang Kleemann
Abstract: Disordered multiferroic materials (type-III multiferroics) escape the conventional schematics of type-I and type-II multiferroics, where two types of ferroic long-range order are expected to coexist under different interdependences and promise to attain a maximized bilinear (α or EH) magnetoelectric effect under special symmetry conditions. Nevertheless sizable higher order ME response occurs also in disordered systems such as in the simultaneous dipolar and spin glasses (multiglass) Sr0.98Mn0.02TiO3 and K0.94Mn0.03TaO3, the quantum paraelectric antiferromagnet EuTiO3, the spin glass and relaxor ferroelectric PbFe0.5Nb0.5O3, and the antiferroelectric antiferromagnetic dipole glass CuCr1-xInxP2S6. They have in common to show large quadratic magneto-capacitance effects, Δε H2, which are related to dominating third-order E2H2 terms in their free energies and do not require special symmetry conditions. The polarization controlled exchange coupling can achieve giant fluctuation-enhanced values in the vicinity of critical magnetic fields as observed, e.g., in EuTiO3. Exceptionally, even the first-order EH-type magnetoelectric effect is observed whenever metastable homogeneous order parameters are induced by field cooling as in EuTiO3, or in the spin glass phase of the relaxor multiferroic Pb (Fe0.5Nb0.5)O3 at T < Tg = 10.6 K.
Authors: Jong Jin Choi, Joo Hee Jang, Dong Soo Park, Byung Dong Hahn, Woon Ha Yoon, Chan Park
Abstract: Lead zinc niobate (PZN) added lead zirconate titanate (PZT) thick films with thickness of 5~10 μm were fabricated on silicon and sapphire substrates using aerosol deposition method. The contents of PZN were varied from 0, 20 and 40 %. The as deposited film had fairly dense microstructure without any crack, and showed only a perovskite single phase formed with nano-sized grains. The as-deposited films on silicon were annealed at temperatures of 700oC, and the films deposited on sapphire were annealed at 900oC in the electrical furnace. The effects of PZN addition on the microstructural evolution were observed using FE-SEM and HR-TEM, and dielectric and ferroelectric properties of the films were characterized using impedance analyzer and Sawyer-Tower circuit, respectively. The PZN added PZT film showed poor electrical properties than pure PZT film when the films were coated on silicon substrate and annealed at 700oC, on the other hand, the PZN added PZT film showed higher remanent polarization and dielectric constant values then pure PZT film when the films were coated on sapphire and annealed at 900oC. The ferroelectric and dielectric characteristics of 20% PZN added PZT films annealed at 900oC were comparable with the values obtained from bulk ceramic specimen with same composition sintered at 1200oC.
Authors: Y.G. Choi, Y.-J. Son, Joon Chul Kwon, K.W. Cho, Soon Young Kweon, Tae Whan Hong, Young Geun Lee, Sung Lim Ryu, Il Ho Kim, Man Soon Yoon, Soon Chul Ur
Abstract: To enhance high power characteristics for piezoelectric transformer, an alloy design approach in PZT base ceramic system was considered. Various Zr/Ti ratio compositions in 0.03Pb(Sb0.5Nb0.5)O3- 0.03Pb(Mn1/3Nb2/3)O3-(0.94-x)PbTiO3-xPbZrO3 (0.445x0.475 mol)[PSN - PMN - PZT] system were synthesized by the conventional bulk ceramic processing technique. To improve high power characteristics at their morphotropic phase boundary (MPB) composition of PSN-PMN-PZT system, various spectra of Zr/Ti ratio were systematically experimented, and their effects on the subsequent piezoelectric properties and dielectric properties for high power piezoelectric transformer application were investigated using an impedance analyzer and a laser vibrometer. Microstructure and phase information were characterized using X-ray diffractometer (XRD) and a scanning electron microscope (SEM). When the Zr/Ti ratios were 0.475/0.465, the mechanical quality factor and electromechanical coupling factor were shown to reach the maximum, indicating that this alloy design can be a feasible composition for high power transformer.
Authors: Satoshi Yokomizo, Takuya Hoshina, Hiroaki Takeda, Katsuya Taniguchi, Youichi Mizuno, Hirokazu Chazono, Osamu Sakurai, Takaaki Tsurumi
Abstract: We researched the phenomenon that the permittivity of dielectric layers in multilayer ceramic capacitor (MLCC) increases with the number of dielectric layers. Finite element method (FEM) shows that the internal residual stress in MLCC was generated by the difference of thermal expansion coefficient between internal electrodes and dielectric layers. We developed a electric measurement system with applying external stress for understanding the stress influence on dielectric properties. The compressive stress along electric field increased the polarization. The polar nano regions (PNRs) in shell composition dielectrics were easily influenced by stress. Based on these results, the relationship between the number of dielectric layers and their permittivity in MLCCs was explained.
Authors: A. Kalvane, M. Antonova, M. Livinsh, M. Kundzinsh, A. Spule, L. Shebanovs, Andris Sternberg
Authors: Ryszard Skulski, Paweł Wawrzała, Dariusz Bochenek, Jan Kulawik, Dorota Szwagierczak, Przemysław Niemiec
Abstract: We present the technology of obtaining and the main properties of multilayered ceramic capacitors (MLCC) based on the PMN-PT-PFN solid solution. PMN-PT-PFN is the abbreviation of the material with general formula (1-y)[(1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3]-yPb(Fe1/2Nb1/2)O3. In our work the investigated material was PMN-PT-PFN with x=0.25, y=0.1 i.e. 0.9(0.75PMN-0.25PT)-0.1PFN. The powder of 0.9(0.75PMN-0.25PT)-0.1PFN has been obtained in three steps. In first step we obtained MgNb2O6. In second step FeNbO4 was obtained. In final third step the 0.9(0.75PMN-0.25PT)-0.1PFN was obtained from mixed powders MgNb2O6, FeNbO4, PbO and TiO2. Thick film pastes for obtaining MLCC were prepared by mixing of PMN-PT-PFN powder with organic vehicle and firing in furnace in the temperature range up to 1050°C. Platinum paste has been used as electrodes. The thickness of single layer was about 45 µm (including electrodes). For obtained MLCC XRD investigations were performed as well as investigations of microstructure, EDS and main dielectric properties.
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