Modeling the dielectric response of lanthanum modified lead zirconate titanate ferroelectric ceramics-an approach to the phase transitions in relaxor ferroelectrics

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Features of dielectric response in PMN-PT ferroelectric ceramics

In this paper, electrical and structural properties were reported for pyrochlore free (1-x)[Pb(Mg1/3Nb2/3)O-3] - xPbTiO(3) (PMN-PT) (with 35 mol% PbTiO3) ceramics obtained from fine powders. Dielectric studies were focused on the investigation of the complex dielectric permittivity (epsilon '-i epsilon '') as a function of frequency and temperature. The effects of the dc applied electric field on dielectric response were also investigated. Results revealed a field dependence dielectric anomaly in the dielectric permittivity curves (epsilon(T)) in the low dc electric field region, which in turn prevails in the whole analysed frequency interval. To the best of our knowledge, these properties for the PMN-PT ceramic system have not been reported before as in this work. The results were analysed within the framework of the current models found in the literature.

Phase transition and dielectric properties of La-doped Pb(Zr, Ti)O-3 antiferroelectric ceramics

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Investigation on dielectric response of PMN ceramics around paraelectric-ferroelectric diffuse phase transition

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Effects of lanthanum modification on dielectric properties of Pb(Zr-0.90,Ti-0.10)O-3 ceramics: enhanced antiferroelectric stability

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Dielectric response features and oxygen migration on rare earth modified lead titanate ferroelectric ceramics

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Domain wall contribution to dielectric and piezoelectric responses in 0.65Pb(Mg1/3Nb2/3)-0.35PbTiO(3) ferroelectric ceramics

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Structural and dielectric characterization of praseodymium-modified lead titanate ceramics synthesized by the OPM route

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Dielectric and ferroelectric characteristics of barium zirconate titanate ceramics prepared from mixed oxide method

Barium zirconium titanate (BZT) ceramics were prepared by mixed oxide method. X-ray diffraction showed the presence of a single phase while Raman scattering confirmed structural transitions as a function of different Zr/Ti ratio. The addition of Zr strongly influenced the crystal structure and electrical properties of the ceramics. A typical hysteresis loops were observed for all investigated compositions. BZT ceramics with 15 mol% Zr have shown a ferroelectric to paraelectric transition at around 77 degrees C. (C) 2007 Published by Elsevier B.V.

Ferroelectric and dielectric properties of vanadium-doped Ba(Ti0.90Zr0.10)O-3 ceramics

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Dielectric investigations of vanadium modified barium zirconium titanate ceramics obtained from mixed oxide method

Vanadium modified barium zirconium titanate ceramics Ba(Zr(0.10)Ti(0.90))O(3):2V (BZT:2V) were prepared from the mixed oxide method. According to X-ray diffraction analysis, addition of vanadium leads to ceramics free of secondary phases. Electrical characteristics reveal a dielectric permittivity at around 15,000 with low dielectric loss with a remnant polarization (P(r))of 8 mu C/cm(2) at 2 kV/cm. From the obtained results, we assume that vanadium substitution in the BZT lattice affects dielectric characteristics due to the electron-relaxation-mode in which carriers (polarons, protons, and so on) are coupled with existing dielectric modes. (C) 2009 Published by Elsevier B.V.

Effects of powder preparation and sintering procedure on microstructure and dielectric properties of PLZT ceramics

PLZT ceramics belong to one of the very important groups of functional materials that make a basis for the production of a large range of electronic devices. The microstructure and properties of ceramics depend on the powder preparation and thermal processing conditions. Various techniques have been used to obtain chemically homogeneous and fine starting powders. PLZT powders have been prepared by two different production routes: by a modified Pechini method, using a polymeric precursor method (PMM) and by a partial oxalate method. A two-step sintering process, including a hot pressing, was carried out at 1100 and 1200degreesC Distinct phases obtained during the sintering process have been investigated by SEM and EDS techniques and dielectric properties such as permittivity and dielectric loss were measured in a frequency range from 1 to 20 kHz.. A significant difference in microstructure and dielectric properties, depending on powder origin and sintering procedure, has been noticed.

Dielectric and piezoelectric properties of the mechanochemically prepared PZT ceramics

Mechanochemical synthesis was applied to obtain nanocrystalline powders of composition Pb(Zr0.52Ti0.48)O-3 (PZT). Milling was performed in a planetary ball mill using vials and balls made of zirconia or steel-in order to investigate influence of milling media on the electrical properties of resulting ceramics. PZT ceramics showed high values for dielectric constant (epsilon(r)), reaching 970 at room temperature, as well as low dielectric loss (tandelta) under the optimal processing conditions. High values of remanent polarization (P-r) indicate high internal polarizability. The best samples showed piezoelectric strain constant d(33) = 347 pC/N and planar coupling factor k(P) = 0.44. Milling in ZrO2 medium prevents powder contamination and provides reproducibility of milling process. Also, PZT obtained from the powders milled in ZrO2 exhibited lower values of dielectric loss, in comparison with the PTZ obtained from the powders milled in Fe. This suggests that contamination of the powder with Fe could result in an increase of conductivity in final product. (C) 2004 Kluwer Academic Publishers.

Dielectric properties of Na1-xLixNbO3 ceramics from powders obtained by chemical synthesis

Ultra-fine powders of Na1-xLixNbO3 (x=0; 0.06; 0.09; 0.12) were synthesized by the Polymeric Precursors Method. Such powders had their orthorhombic structures determined by X-ray diffraction and their surface area determined by BET isotherms (less than 10 m(2) g(-1)). Densification was followed by dilatometric study. The powders, calcined at 700 degrees C for 5 h, were sintered at 1290 degrees C during 2 h under ambient atmosphere with no application of extra pressure. The samples with relative densities higher than 95% were analyzed by impedance spectroscopy at room temperature, under a signal amplitude of 1 V-rms. Dielectric constants of about 180 and dielectric loss factor of about 0.03 were measured showing small dependence with frequency. The electrical properties were similar to those obtained for samples sintered by hot pressing. (C) 1999 Elsevier B.V. Limited and Techna S.r.l. All rights reserved.

Structure, microstructure and dielectric properties of 100-x(Bi0.5Na0.5)TiO3-x[SrTiO3] composites ceramics

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