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Journal ArticleDOI

Electrical Investigations of Aurivillius Type Sr0.7A0.3Bi2Nb2O9 (A = Ca, La and Pb) Ferroelectric Ceramics

24 Sep 2007-Ferroelectrics (Taylor & Francis Group)-Vol. 356, Iss: 1, pp 54-61
TL;DR: In this paper, the effects of 30 atomic % doping of Ca, La and Pb on tetragonal strain, conductivity and dielectric constant/loss with temperature and frequency were discussed.
Abstract: Aurivillius type bismuth layer structured ferroelectrics (BLSF) have been found to possess strong relationship between tetragonal strain (c/a) and extrinsic/ intrinsic conductivity. The extrinsic part of the conductivity is known to depend upon space charge in the sample. The present paper discusses effects of 30 atomic % doping of Ca, La and Pb on tetragonal strain, conductivity and dielectric constant/loss with temperature and frequency. Tetragonal strain increases on doping calcium and lead while it shows a decrease on doping lanthanum. The calcium and lanthanum doped samples show pronounced space charge part of dielectric constant while lead doped sample shows nearly constant permittivity values. No phase transition is observed in the calcium doped sample up to 600°C while for the lanthanum doped sample a decrease of 141°C is observed in the value of Curie temperature compared to that for the undoped sample.
Citations
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Journal ArticleDOI
TL;DR: In this article, a single-phase Bismuth layer-structured (Bi 7− x Sr x )(Fe 3− x Ti 3+ x )O 21 (BSFT) ceramics were synthesized and the ferroelectric properties and crystal structure were investigated.
Abstract: Bismuth layer-structured (Bi 7− x Sr x )(Fe 3− x Ti 3+ x )O 21 (BSFT) ceramics were synthesized and the ferroelectric properties and crystal structure were investigated. X-ray powder diffraction profiles and refinement of the lattice parameters indicated single phase BSFT was obtained in the composition range 0–1.5. The lattice parameter b of BSFT remained almost constant, while a slight decrease in the lattice parameter a was observed by the Sr and Ti substitution for Bi and Fe, respectively, which indicated an increase in the orthorhombicity. The dependence of the BSFT lattice parameter on temperature implied a phase transition from the orthorhombic to the tetragonal phase, which was in good agreement with the Curie temperature. The remnant polarization P r , of BSFT was significantly improved by the Sr and Ti substitution for Bi and Fe, and ranged from 9 to 16 μC/cm 2 , although no remarkable variation in the coercive field E c was observed. As a result, a well-saturated P – E hysteresis loop of BSFT ceramic was obtained at x =0.5 with a P r of 30 μC/cm at an applied voltage of 280 kV/cm.

15 citations

Journal ArticleDOI
TL;DR: In this article, X ray diffraction analysis reveals the formation of single phase perovskite structure of SBNs and a slight change in the lattice parameters is observed.
Abstract: In the present work, samples of compositions SrBi 2 Nb 2 O 9 and SrBi 2 Nb 1.9 Mo 0.1 O 9 were prepared by solid state reaction method. X ray diffraction analysis reveals the formation of single phase perovskite structure. Although the perovskite structure of SBN is retained but slight change in the lattice parameters is observed. Dielectric constant and dielectric loss have been measured as a function of temperature (300 K–800 K) and frequency (1 kHz, 10 kHz and 100 kHz). Peak Dielectric constant is observed to increase from 465.05 for pure SBN to 613.17 for molybdenum substituted SBN while Curie temperature is observed to decrease from 420°C for pure SBN to 365°C for molybdenum substituted SBN. Dielectric loss is observed to increase from 0.066 for pure SBN to 0.123 for the doped sample at their respective Curie temperature. P-E loops have been recorded and retentivity and coercevity have been determined. The coercive field and remanant polarization values are observed to decrease from 10.647 μzv/c.m. a...

12 citations

Journal ArticleDOI
TL;DR: In this article , the authors examined the strain-induced ferroelectric properties of Bi3TaTiO9 (BTTO) thin films and showed that the BTTO thin film on the single crystal Rh and Nb-doped SrTiO3 (Nb:STO) substrates via a pulsed laser deposition were compared.

2 citations

Proceedings ArticleDOI
03 Nov 2009
TL;DR: In this article, the effect of sintering temperature on structural, dielectric and electrical properties of vanadium substituted strontium bismuth niobate ferroelectric ceramics have been studied.
Abstract: In the present work, effect of sintering temperature on structural, dielectric and electrical properties of vanadium substituted strontium bismuth niobate ferroelectric ceramics have been studied. Samples of composition SrBi 2 Nb 1.9 V 0.1 O 9 were synthesized by solid-state reaction method at different sintering temperatures. X - ray diffraction analysis reveals the formation of perovskite structure. Peak dielectric constant is found to increase with increasing sintering temperature while Curie temperature is observed to be the highest in the sample sintered at 900 °C and it decreases in the sample sintered at 1000 °C. Impedance analysis of the samples was carried out to study the grain and the grain boundary effects. Cole-cole plots reveal a decrease in bulk resistance on increasing temperature indicating NTCR behavior.

Cites background from "Electrical Investigations of Aurivi..."

  • ...SrBi2Nb2O9 have attracted the attention of the researchers in recent years due to its large remanent polarization, low coercive field, low leakage current, high Curie temperature, lower sintering temperature and being lead free [1-5]....

    [...]

References
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Journal ArticleDOI
01 Oct 1999-Nature
TL;DR: Work on a particular form of ferroelectric material provides encouraging evidence that it has the desired properties for nonvolatile memory.
Abstract: One elusive goal in semiconductor technology is realizing the ideal nonvolatile memory -- that is, one that retains information when the power is switched off without battery back-up. In this context, so-called ferroelectric random access memories are promising. Work on a particular form of ferroelectric material provides encouraging evidence that it has the desired properties for nonvolatile memory.

148 citations

Journal ArticleDOI
TL;DR: In this paper, an experimental study on the influences of 10% Ca2+ and La3+ doping on dielectric properties and dc conductivity of SrBi2Nb2O9 ferroelectric ceramics was conducted.
Abstract: In this letter, we report an experimental study on the influences of 10 at. % Ca2+ and La3+ doping on dielectric properties and dc conductivity of SrBi2Nb2O9 ferroelectric ceramics. All the samples were made by two-step solid-state reaction sintering at temperatures up to 1150 °C for 0.5–1 h in air. X-ray diffraction analysis indicated that single-phase layered perovskite ferroelectrics were obtained and no appreciable secondary phase was found. The Curie point was found to increase from 418 °C without doping to 475 °C with Ca2+ doping and to 480 °C with La3+ doping. Dielectric constants, loss tangent, and dc conductivity of SrBi2Nb2O9 ferroelectrics doped with Ca2+ and La3+ were studied and the relationships among doping, crystal structure, and dielectric properties were discussed.

133 citations

Journal ArticleDOI
TL;DR: In this article, a reported theory originally derived for rhombohedral-phase PLZT 6/65/35 ceramics is shown to be applicable to tetragonal-phase polyhedral-plzT 6.1/35 (PLZT6/65)/35 (P6/35)-ceramics also by introducing the remanent degree of 90° domain alignment γ90.
Abstract: The polarization reversal of some tetragonal-phase PLZT ceramics is studied. The results are explained in terms of 90° domain wall motions. A reported theory originally derived for rhombohedral-phase PLZT 6/65/35 ceramics is shown to be applicable to tetragonal-phase PLZT ceramics also by introducing the remanent degree of 90° domain alignment γ90. As a result, the calculation of coercive force is possible for various PLZT compositions considering the interaction of 90° domain wall motions and reacting forces established by the internal stress state of ferroelectric ceramics. The frequency dependence of coercive force and measurements of switching strain, including depolarization data obtained from either mechanically or electrically produced external forces, confirm the interpretation of predominantly occuring 90° reorientations and are consistent with the extended theory.

59 citations

Journal ArticleDOI
TL;DR: In this paper, an analysis of the contrasting consequences of the competing orthorhombic and pseudotetragonal symmetries in SBT was done, showing that the anisotropy in this plane is small in the frequency range from 300 to 1200 cm.
Abstract: Experimental studies were carried out on infrared-active phonons in the Aurivillius ferroelectric SrBi2Ta2O9 ~SBT!, using reflectivity measurements ~down to 200 cm! and transmission measurements ~down to 100 cm! on crystals, pellets, and thin films. An analysis was done of the contrasting consequences of the competing orthorhombic and pseudotetragonal symmetries in SBT. Reflectivity results for light polarized in the ab plane show that the anisotropy in this plane is small in the frequency range from 300 to 1200 cm, indicating the influence of the approximate tetragonal symmetry. Dielectric dispersion properties were derived for this polarization (E'c) in this frequency range. The transverse-optical ~TO! and longitudinal-optical ~LO! frequencies corresponding to the dominant E'c band are 613 and 773 cm, respectively. This strong, highfrequency band arises from a mode dominated by the motion of the oxygen sublattice; its TO and LO frequencies yield an oxygen-ion Szigeti effective charge of 21.5e . Frequency estimates for the TO ~LO! pairs of other strong bands are 188~330! and 334(451) cm for E'c , and 610~675! and 780(815) cm for Eic . In addition to the main infrared bands, the main Raman bands of SBT are also reported. @S0163-1829~98!03010-0#

55 citations