Structural and electrical studies in La-substituted SrBi2Nb2O9 ferroelectric ceramics
TL;DR: In this article, structural and electrical studies of A-site lanthanum-substituted Sr1−xLaxBi2Nb2O9; x = 0.0, 0.4 and 0.5 samples are reported.
Abstract: In this paper, structural and electrical studies of A-site lanthanum-substituted Sr1−xLaxBi2Nb2O9; x = 0.0 – 0.5 ceramics are reported. The introduction of lanthanum produces pore-free microstructure upto x = 0.3 . A diffuse ferroelectric to paraelectric phase transition is observed in the doped samples and positive temperature coefficient of resistance (PTCR) is observed in x = 0.0 , 0.4 and 0.5 samples whereas x = 0.1 – 0.3 samples show negative temperature coefficient of resistance (NTCR). Curie temperature decreases continuously with increase in lanthanum content.
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TL;DR: In this article, a review of the potential of bismuth-containing heterometallic oxides is presented together with feasible applications of the latter, and a variety of structurally related high-nuclearity molecular Bismuth oxo clusters are discussed that serve as model compounds.
274 citations
TL;DR: In this article, complex impedance analysis of polycrystalline tungsten-bronze structured Ba5SmTi3Nb7O30 prepared by a solid-state reaction method was performed.
82 citations
TL;DR: In this article, the effect of sintering temperature on densification, grain size, conductivity and dielectric properties of Sr1−x(Na 0.5Bi0.5) and Bi2Nb2O9 ceramics was investigated.
Abstract: In this study, we investigated the effect of sintering temperature on densification, grain size, conductivity and dielectric properties of Sr1−x(Na0.5Bi0.5)
x
Bi2Nb2O9 ceramics, prepared by hydrothermal method. Pellets were sintered at different temperatures. Density increased with sintering temperature, reaching up to 96% at 800 °C. A grain growth was observed with increasing sintering temperature. Impedance spectroscopy analyses of the sintered samples at various temperatures were performed. Increase in dielectric constant and in Curie temperature with sintering was discussed. Electrical conductivity and activation energy were calculated and attributed to the microstructural factors.
50 citations
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...This suggests the presence of negative temperature coefficient of resistance (NTCR), a characteristic of dielectrics [73]....
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TL;DR: In this article, complex impedance analysis of polycrystalline complex perovskite structured BaZr 0·025Ti 0·975O3 prepared by solid state reaction method was performed.
Abstract: This paper reports complex impedance analysis of polycrystalline complex perovskite structured BaZr 0·025Ti 0·975O3 prepared by solid state reaction method. XRD analysis reveals the formation of single phase perovskite structure. SEM has been used to investigate grain morphology of the material. Impedance plots have been used as a tool to analyse electrical properties of the sample as a function of frequency and temperature. Bulk resistance is observed to decrease with an increase in temperature showing a typical negative temperature coefficient of resistance (NTCR) type behaviour. Nyquist (Cole–Cole) plots show both inter and intra grain boundary effects. Relaxation time is found to decrease with increasing temperature and it obeys the Arrhenius relationship. The variation of d.c. and a.c. conductivity as a function of temperature is also reported.
49 citations
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...This manifests a negative temperature coefficient of resistance (NTCR) behaviour, a typical characteristic of dielectric materials (Buchanan 1991; Shrivastava et al 2006)....
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TL;DR: In this paper, the dielectric properties of nanocrystalline powders of Bi-substituted SBN ceramics were analyzed through XRD and TEM.
34 citations
References
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TL;DR: Ferroelectric ceramics have been the heart and soul of several multibillion dollar industries, ranging from high-dielectric-constant capacitors to later developments in piezoelectric transducers, positive temperature coefficient devices, and electrooptic light valves as mentioned in this paper.
Abstract: Ferroelectric ceramics were born in the early 1940s with the discovery of the phenomenon of ferroelectricity as the source of the unusually high dielectric constant in ceramic barium titanate capacitors. Since that time, they have been the heart and soul of several multibillion dollar industries, ranging from high-dielectric-constant capacitors to later developments in piezoelectric transducers, positive temperature coefficient devices, and electrooptic light valves. Materials based on two compositional systems, barium titanate and lead zirconate titanate, have dominated the field throughout their history. The more recent developments in the field of ferroelectric ceramics, such as medical ultrasonic composites, high-displacement piezoelectric actuators (Moonies, RAINBOWS), photostrictors, and thin and thick films for piezoelectric and integrated-circuit applications have served to keep the industry young amidst its growing maturity. Various ceramic formulations, their form (bulk, films), fabrication, function (properties), and future are described in relation to their ferroelectric nature and specific areas of application.
3,442 citations
TL;DR: In this article, the authors describe the preparation and characterization of thin-film capacitors using ferroelectric materials from a large family of layered perovskite oxides, exemplified by SrBi2Ta2O9, SRBi2NbTaO9 and SrBi4Ta4O15.
Abstract: A SIGNIFICANT fraction of the computer memory industry is at present involved in the manufacture of non-volatile memory devices1—that is, devices which retain information when power is interrupted. For such applications (and also for volatile memories), the use of capacitors constructed from ferroelectric thin films has stimulated much interest1. In such structures, information is stored in the polarization state of the ferroelectric material itself, which should in principle lead to lower power requirements, faster access time and potentially lower cost1. But the use of ferroelectrics is not without problems; the memories constructed to date have generally suffered from poor retention of stored information and degradation of performance ('fatigue') with use1–3. Here we describe the preparation and characterization of thin-film capacitors using ferroelectric materials from a large family of layered perovskite oxides, exemplified by SrBi2Ta2O9, SrBi2NbTaO9 and SrBi4Ta4O15. The structural flexibility of these materials allows their properties to be tailored so that many of the problems associated with previous ferroelectric memories are avoided. In particular, our capacitors do not show significant fatigue after 1012 switching cycles, and they exhibit good retention characteristics and low leakage currents even with films less than 100 nm thick.
2,378 citations
TL;DR: In this paper, transparent ferroelectric ceramic materials suitable for a variety of electrooptic applications were found in the quaternary (Pb,La,Zr,Ti)O3 system.
Abstract: Transparent ferroelectric ceramic materials suitable for a variety of electrooptic applications were found in the quaternary (Pb,La)(Zr,Ti)O3 system. These PLZT materials are prepared from mixed oxides and hot-pressed typically at 1100°C for 16 h at 2000 psi. Modifying the lead zirconate-titanate system with lanthana linearly reduces the Curie point with increasing lanthana. Transmission measurements in the visible and infrared show that these materials exhibit a nearly constant response from the absorption edge of 0.37 μ to ∼6 μm. The highest transmission values, essentially 100% (neglecting reflection losses of ∼18%) for thin polished plates, were noted for compositions containing 8 at.% La or more. Specific compositions within the system display electrooptic memory or conventional linear or quadratic electrooptic effects; on the basis of the magnitude of the electrooptic effects, they compare quite favorably with single crystals.
1,002 citations
TL;DR: In this article, three sets of oxygen vacancies related dielectric peaks (peaks A, B, and C) were measured from 10 to 800 K. The results show that the Maxwell-Wagner polarization is not the main mechanism, and the Skanavi's model also cannot be directly applied.
Abstract: The temperature dependence of dielectric properties and electrical conduction of $({\mathrm{Sr}}_{1\ensuremath{-}1.5x}{\mathrm{Bi}}_{x}){\mathrm{TiO}}_{3} (0.0133l~xl~0.133)$ was measured from 10 to 800 K. Three sets of oxygen vacancies related dielectric peaks (peaks A, B, and $C)$ were observed. These peaks could be greatly suppressed or eliminated by annealing the samples in an oxidizing atmosphere, and enhanced or recreated by annealing in a reducing atmosphere. The results show that the Maxwell-Wagner polarization is not the main mechanism, and the Skanavi's model also cannot be directly applied. A tentative explanation was suggested. Peak A, observed in the temperature range of 100--350 K with the activation energy for dielectric relaxation ${E}_{\mathrm{relaxA}}=0.32--0.49$ eV, is attributed to the coupling effect of the conduction electrons with the motion of the off-centered Bi and Ti ions; the conduction carriers in this temperature range are from the first ionization of oxygen vacancies ${(V}_{o}).$ Peaks B and C are also discussed.
855 citations
Book•
01 Jan 1990
TL;DR: In this paper, the band theory of solids semiconductors ionic and defect conductors linear dielectrics nonlinear dielectric magnetic ceramics photonic and optical waveguides optical waveguide glass and crystalline lasers ceramic superconductors.
Abstract: Quantum mechanics and the band theory of solids semiconductors ionic and defect conductors linear dielectrics nonlinear dielectrics magnetic ceramics photonic ceramics optical waveguides electro-optical ceramics glass and crystalline lasers ceramic superconductors.
487 citations