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The spark-plasma sintering of ceramics based on the cubic pyrochlore phase in the system Bi2O3-ZnO-Nb2O5 is reported for the first time. It is shown that the use of spark-plasma sintering in the manufacture of (Bi1.5Zn0.5)2(Zn0.5Nb1.5)2O7 ceramics makes it possible to obtain a high density, a homogeneous microstructure, and high dielectric parameters (almost 30% higher compared to conventional ceramic technology). The paper discusses the features of microstructure formation and the optimization of spark plasma sintering regimes. [ABSTRACT FROM AUTHOR]

In our earlier studies we have shown procedure for the estimation of activation energy and relaxation times directly from the dielectric and AC conductivity data simultaneously dependant on T and ω using modified Lorentz equation instead of well-known Arrhenius, modified Arrhenius and Vogel-Fulcher laws. In the present paper we have carried out similar experimental and simulation studies on the dielectric and AC conductivity data using modified Lorentz equations on the ceramic compound (Ba0.997Pr0.003TiO3). The obtained results on the activation energy and relaxation times are presented in this paper. [ABSTRACT FROM AUTHOR]

Synthesis (via solid-state reaction) and characterization (structure, microstructure, dielectric, electrical, and ferroelectric behavior) of brownmillerite polycrystalline material NaBiFe2O5 (NBFO) are discussed in this paper. The formation of a triclinic structure has been analyzed by the X-ray diffraction method. The morphology of the ceramic sample was analyzed using a field emission scanning electron microscope (FESEM) and energy-dispersive X-ray analysis (EDX). It is found that the grains are uniformly distributed through well-defined grain boundaries of the sample containing all the constituent elements (Na, Bi, Fe, and O). The study of both frequency (1 kHz–1MHz) and temperature (25–450 °C) dependent dielectric and AC-conductivity predicts the presence of Maxwell-Wagner type of dielectric dispersion and thermally activated relaxation mechanism of NBFO. The impedance spectra support the semiconducting behavior of the brownmillerite NBFO at high temperature. The resistance of the material falls with a rise in temperature favors the negative temperature coefficient resistance behavior of the material. The study of electric polarization suggests the possibility of the ferroelectric properties of the studied sample. The high dielectric constant and low tangent loss suggest the possibility of the material for device applications. [ABSTRACT FROM AUTHOR]

We argue that the "N-aeetyl glycine phosphite " crystal grown and characterized in the title paper actually is glycine phosphite. [ABSTRACT FROM AUTHOR]

This paper presents the results of a study of the dielectric response in single crystals of barium strontium niobate doped with thulium of various concentrations. It is shown that the dielectric permittivity increases with increasing concentration of thulium. For as-grown samples the dispersion of the permittivity is observed in the frequency region of 106 Hz. The dependence is not observed for the samples polarized under DC field. For all the samples studied, the switched polarization increases and the coercive field decreases under action of an AC field. [ABSTRACT FROM AUTHOR]

The paper presents some general patterns of the temperature behavior of thermodepolarization currents, dielectric permittivity and conductivity of dielectric materials containing water molecules or hydrogen bonds – crystallohydrates, polyelectrolytes, and biopolymers. The results indicate that the anomalies of these properties are observed at 4, 20, 35, 46, 65–76°С, which are "threshold points" of water, when its structure changes abruptly. The observed anomalies are probably due to a change in the proton energy at a transition to an excited level in the double-well potential at heating, while the equilibrium of the system is achieved by slow stepwise heating. [ABSTRACT FROM AUTHOR]

In this paper, the study of relaxation processes in ferroelectric ceramics under the influence of a dc electric field has been performed. To measure the field and time dependences of the complex elastic, dielectric, and piezoelectric parameters of ferroelectric ceramics, the impedance spectroscopy method and piezoelectric resonance analysis program were used. A comparative analysis of various characterization methods was carried out, and a physical interpretation of the results has been proposed. [ABSTRACT FROM AUTHOR]

In this paper, studies on the preparation and properties of barium sodium titanate niobate and poly(vinylidenefluoride) (PVDF) bulk composites are reported. SEM images show ceramic particles incorporated into the PVDF matrix in a 0–3 connectivity. FTIR results reveal that BTNN was formed without undesirable phases and that the β-phase of polymer is present. Dielectric studies show a relaxor ferroelectric behavior with a real dielectric constant of ∼56 (300 K at 1 kHz) and a maximum dielectric loss of 7%. This value is the highest among those reported for PVDF-ceramic composites with 30% of ceramic phase in their matrices. [ABSTRACT FROM AUTHOR]

The "National Seminar on Ferroelectrics and Dielectrics" (NSFD) is a biennial seminar that has been held in India since 1980. The seminar focuses on the physics, chemistry, and engineering aspects of ferroelectrics and dielectrics, which are materials used in modern technology for applications such as data storage and wireless communications. The 22nd NSFD took place at VIT-AP University in Andhra Pradesh, India, and covered topics including materials design, characterization, and theoretical modeling. The seminar facilitated the exchange of scientific ideas and resulted in the publication of 89 papers in a special issue of Ferroelectrics. [Extracted from the article]

This paper is focused on the research an improved version of the Boltzmann-Poisson model for BaTiO3-ceramics. In the approximation of one relaxation time, for constant external electrical field, this approach included correct quadratic relation for varistor effect in the case of the Heywang model. Within meso-kinetics, quantum corrected Boltzmann-Poisson model, contains space-time correlations for the probability distribution density function f(r, k, t), lead to correct fractional relaxation velocity description. These new results corresponds to our other research based on electronic particles Brownian motion within its fractal nature. [ABSTRACT FROM AUTHOR]

The paper presents synthesis of (1-x)PMN-(x)PT (PMN-PT) near morphotropic phase boundary (MPB) i.e. for x = 0.25, 0.31, 0.33 and 0.35, using hydroxide co-precipitation method. Further, PMN-PT compositions under investigation were systematically characterized for density, structural, morphological, dielectric and ferroelectric properties. X-ray diffraction data reveals single phase formation of PMN-PT. The scanning electron microscopy (SEM) images were recorded and used to understand morphology of the samples. In present study, it was noted that the PMN-PT composition with x = 0.25 exhibits the maximum value of dielectric constant (ϵ) and saturation polarization (Pmax) amongst the PMN-PT compositions under investigation. [ABSTRACT FROM AUTHOR]

This paper is focused on dielectric properties of potassium niobate (KN) –barium titanate (BT) composites with artificial morphotropic phase boundary (MPB). Ceramics with highest concentration of KN showed a glassy behaviour below 300 K temperature. Also two relaxation processes were observed, one in MHz and second at GHz range. The relaxation process in the MHz range follows Vogel-Fulcher law. The nature of the GHz dispersion is assumed to be electro-mechanical resonance. [ABSTRACT FROM AUTHOR]

There has been a great deal of interest in periodic dielectric structures that exhibit photonic band gaps. Periodicity in dielectric constant results in a range of frequencies within which transmission is forbidden, known as Photonic Band Gaps (PBG). PBG structures can be used as tunable filters whose bandwidth can be varied depending on the periodicity, dielectric constant etc. It is possible to construct PBG structures with one-dimensional periodicity. In this paper, we report the experimental observation of the band gaps between 10 and 20 GHz for a structure made of lossy glass slabs (ε r ′ = 6.1 , ε r ” = 0.06 ). This paper also presents the results on the numerical computation using transfer matrix method for the above structure for comparison. The nature of the band gaps is also investigated with respect to the spacing between the dielectric slabs and dielectric constant. [ABSTRACT FROM AUTHOR]

Complex perovskite materials are considered as a boon in this revolutionary era of microelectronic and telecommunications. In this paper we have presented the effect of replacement of Mg2+by divalent ions (Co2+, Cu2+) in Ba(Mg0.33Nb0.67)O3. We have studied the impact of replacement of Mg2+by transition elements on structural, micro-structure, dielectric properties. It is observed that on replacing the Mg2+by Co2+and Cu2+the structural symmetry shifts from hexagonal (BMN, BCoN) to tetragonal (BCuN). Further, the morphological study reveals agglomerated grain formation for BCoN and a spikes/elongated type of structure in BCuN samples. The frequency dependence of dielectric studies shows the polar behavior of BMN. On the other hand replacing Mg by cobalt or copper (having 3d7and 3d9configuration, respectively), leads to Jahn-Teller distortions introduced in the samples. The poly-dispersive natures of the samples were inferred through fitting the curves with Cole–Cole equation. [ABSTRACT FROM AUTHOR]

Aurivillius phase (Li,Ce) doped CaBi4Ti4O15(CBT) ceramics were prepared using the conventional solid state methods. The crystal structure and microstructure were determined by X-ray diffraction and scanning electron microscopy. It was found that the (Li,Ce) ions diffused into the A site of CBT's pseudo-perovskite structure and formed a single Aurivillius type structure. The Curie-temperature (TC) of CBT based ceramics decreased whereas the piezoelectric coefficient (d33) was improved with an increase of (Li,Ce) dopants. The detailed electrical properties for Ca0.85(LiCe)0.075Bi4Ti4O15ceramics in the high temperature region were determined using electrochemical impedance spectra. It was found that oxygen vacancies make a major contribution to both electrical conduction and dielectric relaxation. The ac conductivity was found to obey Jonscher's universal law. In addition, the physical nature of electrical conduction and dielectric relaxation was addressed in this paper. [ABSTRACT FROM AUTHOR]

The paper presents synthesis, sintering procedure, microstructure and dielectric properties of a new high permittivity perovskite material relative to Cu2Ta4O12, with the composition Bi2/3CuTa4O12. Impedance spectroscopic studies carried out at frequencies 10 Hz–2 MHz and in a temperature range –55 to 740°C revealed two dielectric responses. The high-frequency and low-temperature response was attributed to grains, and the low-frequency and high-temperature one - to grain boundaries. The high dielectric permittivity was suggested to be related to spontaneous formation of internal barrier layers at the grain boundaries of the semiconducting grains. [ABSTRACT FROM AUTHOR]

In this paper, the (Ba,Ca)(Ti,Zr)-MLCCs with nickel electrodes by free sintering and constrained sintering as different heating rate have been investigated as different heating rate with 200°C/hr, 1500°C/hr and 3000°C/hr, respectively. The BaTiO3 was adopted as constraining layer due to the tensile stress of generation resulted from the different onset temperature. The electrical characteristics were closely related to the microstructure change including electrode overlap areas and grain size by free and constrained sintering with different heating rate. The variation of dielectric constant and insulation resistance can be explained by grain size change. The variation of dielectric loss can be explained by the curve of the temperature coefficient of capacitance. To compare with the free sintering, the capacitance value of constrained sintering of MLCCs has increased regardless of the heating rates. The high capacitance, high electrode continuity (>98%) and high insulation resistance (>1010Ω) of BCTZ-based MLCC with nickel electrode can be attained by using a rapid constrained sintering technique. [ABSTRACT FROM PUBLISHER]

The ac conductivity and relaxation mechanism in Ag(Ta,Nb)O3 ceramics have been investigated systematically. The formation of the ceramics was checked by an X-ray diffraction (XRD) technique analysis. The dielectric permittivity and the loss tangent of the Ag(Ta,Nb)O3 specimen were measured in a frequency range from 1 to 100 kHz at the various temperature ranges (30–110°C). A study on dielectric properties reveals the electrical relaxation phenomenon occurs in the material. Studies on the frequency and temperature dependence of ac conductivity of the Ag(Ta,Nb)O3 ceramics suggest that conduction process in the material is thermally activated process. In this paper, we will discuss the dielectric properties and the ac conductivities of Ag(Ta,Nb)O3 ceramics in relation to the electrical conduction process. [ABSTRACT FROM PUBLISHER]

Investigations presented in the present work are concerning the other member of the Aurivillius family, the BaBi2Nb2O9 (BBN). This compound, which seems to be very interesting from the potential applications point of view. The dielectric characterization of this materials and influence of sintering condition on grain structure and properties of those materials had been very widely described in our previous paper. Now we would like to present the hitherto unreported electric properties of BaBi2Nb2O9 ceramics, investigated by the impedance spectroscopy (IS). IS is nondestructive method, which allows to separate grain and grain – boundary effects due to the different frequencies of the relaxation process in grain and grain boundaries. This enables us to determine the temperature dependences of grain (Rg) and grain-boundary (Rgb) resistance and evaluate their respective activation energies (Ea). Additionally a comparison between macroscopic results obtained by Impedance Spectroscopy and miroscopic direct local LC-AFM conductivity measurements are presented. [ABSTRACT FROM PUBLISHER]

The paper presents results of studies of the dielectric response and structure of the PbCo1/3Nb2/3O3 (PCN) crystal. Analysis of the dielectric response at frequencies ranging from 10 Hz to 50 kHz has revealed a considerable dispersion in a wide temperature interval. Anomalies in the temperature dependences of ε' and ε'' in the vicinity of 350, 250, and 130 К have been observed. It is shown that the anomaly near 250 K can be attributed to the transition into a relaxor ferroelectric state, whereas the anomaly at 130 K occurs nearby to the antiferromagnetic phase transition. The behaviour of the dielectric response in the vicinity of 350 К requires further studies. The PCN crystal structure at room temperature has been refined. [ABSTRACT FROM AUTHOR]

This paper describes an automated-measurement system of ferroelectric hysteresis loops, which was developed in LabView environment based on Virtual Instrument. The system provides a function obtaining nonlinear polarization current from measured current data, which is important for properly estimating ferroelectricity of a dielectric, especially for one with high electric loss. In addition, the relationship between nonlinear polarization current density and external electric field of a ferroelectric reveals more information which is helpful for researches of polar order and/or ferroelectric characteristics. [ABSTRACT FROM AUTHOR]

This paper investigated dielectric properties of rare earth (Y, Gd, Yb)-doped barium titanate sintered in pure nitrogen. The difference in doping behaviors of intermediate rare-earth ions (Gd, Y, Yb) and their effects on the dielectric properties of barium titanate were investigated. The intermediate rare earth elements (Gd, Y, Yb) were substituted in the A-site of the perovskite lattice. The different rare earth element had a crucial effect on dielectric properties of rare-earth-doped BaTiO3. Gd-doped barium titanate had the largest dielectric constant (about 20000) and the largest dielectric loss (about 0.6), the smallest leakage current and no tunability. Y-doped specimen had the largest leakage current. [ABSTRACT FROM AUTHOR]

The phase composition and microwave dielectric properties of xLnAlO3-(1-x)Ln1/3NbO3 (Ln: LA, Nd, 0 ≤ x ≤ 0.9) have been investigated by XRD, EDS, SEM and network analyzer in this paper. All samples with x>0 exhibited multiple phases. Both of dielectric permittivity and temperature coefficient of resonant frequency decreased with the increase of x when x<0.4 and varied little with further increasing x. Q × f value increased with the increase of x. Good combined microwave dielectric properties could be obtained for the samples with x = 0.9: εr = 22.4, Q × f = 49439GHz, τf = -30ppm/°C for La-series and εr = 21.1, Q × f = 54540GHz, τf = -44.8ppm/°C for Nd series. [ABSTRACT FROM AUTHOR]

This paper investigated the ferroelectric and dielectric properties of Sm-doped BaTiO3 sintered in different atmosphere. The influence of variable doping concentration on microstructure, ferroelectric and dielectric properties was studied. The results showed that the dielectric-temperature curve of Sm-doped BaTiO3 was smoother than that of pure BaTiO3. And tunability of Sm-doped BaTiO3 was smaller than that of pure BaTiO3. Dielectric constant of the samples sintered in nitrogen was smaller than that of samples sintered in air. The hysteresis loop displayed that ferroelectric polarization decreased with Sm doping. [ABSTRACT FROM AUTHOR]

This paper investigated the effect of PZT30/70 seed layer as a nucleation aid on the microstructure and electrical properties of 0.93PMN-0.07PT thin films. Pyrochlore phase was totally eliminated at an annealing temperature as low as 650°C. Seeded 0.93PMN-0.07PT thin film possessed a denser structure, larger grain size, and thus higher permittivity, spontaneous polarization and pyrocoefficient than unseeded film. The slim P-E loops and the frequency dependent Tm observed in both films indicated a relaxor-like behavior. [ABSTRACT FROM AUTHOR]

This paper reports on fabrication and characterization of low-temperature-sintered barium-strontium titanate (BST) ceramics with B-Li glass as sintering aid. With the addition of B-Li glass, the sintering temperature of BST can be effectively reduced from 1350 to 920°C due to the presence of a liquid phase. The effects of B-Li glass addition on phase composition, microstructure, dielectric properties, and microwave properties of the BST ceramics were sytematically investigated. The sample (Ba0.50Sr0.50TiO3) with 5.0 wt% B-Li sintered at 920°C for 5 h exhibits optimized room temperature dielectric properties, including a moderate dielectric constant (ε = 1051), a low dielectric loss (0.0048) and a high tunability (31%) at dc electric field of 45 kV/cm and 10 kHz. At 1.150 GHz, it possesses a dielectric constant of 695 and Q value of 207. [ABSTRACT FROM AUTHOR]

In this paper, single-phase nanocrystalline La1-xSrxFeO3 (x = 0.1, 0.2, 0.3, 0.4 and 0.5) with perovskite structure were prepared by employing sol-gel method. XRD and TEM were used to characterize the materials. Dielectric properties of La1-xSrxFeO3 (x = 0.1, 0.2, 0.3, 0.4 and 0.5) were investigated. The experiments were carried out as a function of Sr doping (0.1 ≤ x ≤ 0.5) and frequency (10-105 Hz) in different relative humidity (RH) at 25°C. The results revealed that capacitance decreased as the frequency increased, and the peaks of dielectric loss appeared at high relative humidity range. Humidity sensing properties were also studied in this work. It was found that La0.7Sr0.3FeO3 exhibited high humidity sensitivity and small hysteresis from 33% RH to 98% RH. [ABSTRACT FROM AUTHOR]

This paper reports a ferroelectric-to-paraelectric (FE-PE) two-step transition in the acceptor-doped ferroelectric systems. In ceramic samples, the DSC peak as well as the dielectric permittivity peak exhibits a split after aging at DSC peak temperature. Such phenomenon also exists in the grain-boundary-free single crystal samples; this excludes the possibility of a grain boundary effect. Moreover, the in-situ optical microscopy observation during heating proves that such peak split is due to a two step FE to PE transition. The microscopic explanation is given based on the symmetry-conforming properties of point defects. [ABSTRACT FROM AUTHOR]

(Sr1-xPbx)TiO3 (SPT)-MgO composites are promising for room temperature electric field tunable applications. The composites show a significant processing dependence of dielectric properties. This paper reviews dielectric characteristics of SPT-MgO composites, such as permittivity, loss tangents, dielectric maximum temperature, tunability, and hysteresis under bias. In addition, factors which influence tunability and dielectric properties are described. [ABSTRACT FROM AUTHOR]

In the present paper, we report low frequency ac conductivity and dielectric studies on the composites of conducting polyaniline (PANI) with crystalline zinc tungstate (ZnWO4) powder. These composites have been synthesized by single step in situ polymerization technique by placing fine grade powder of ZnWO4 during the polymerization of aniline. The composites thus formed were characterized by FTIR spectra and scanning electron microscopy (SEM), which conforms the presence of ZnWO4 in polyaniline matrix and the formation of the composite. AC conductivity and dielectric response of these composites were investigated in the frequency ranging from 50 Hz to 5 MHz. it was found that the ac conductivity obeyed the power law index, where the ac conductivity increases with frequency. PANI/ZnWO4 composites have shown high dielectric constant, which could be related to conductivity relaxation phenomenon. It is observed that both dielectric constant and dielectric loss have decreased with increase in frequency. Variations in measured parameters of AC response with increase frequency of the composites follow systematic trends that are similar to those observed with decreasing temperature and level of doping. [ABSTRACT FROM AUTHOR]

This paper examines whether emergent behaviour is observed in dielectric composites, i.e. mixtures of two phases with zero conductivity and of permittivity ε1 and ε2. The model developed enabled the study of random capacitor networks which contain capacitors of two different magnitudes (C1 and C2), which represent the two individual dielectric phases of a composite. The effective capacitance of the network was examined as a function of the individual capacitor magnitudes and their volume fraction. The capacitor networks exhibit an emergent region where there is low variability between individual random networks of a particular composition. The logarithm of the network capacitance scaled linearly with the logarithm of the capacitance ratio (C1 and C2), indicating that under particular conditions a logarithmic mixing rule can be used to determine the properties of dielectric mixtures. [ABSTRACT FROM AUTHOR]

In the present paper the dielectric investigation results of NaNO2 and NaNO3 confined in porous glass are presented. The phase transition in nanoconfined NaNO2 with pore size 20 nm remains nearly at the same temperature. Two phase transitions can be seen in the dielectric spectra. The increase in the frequency dependent dielectric permittivity on heating is mainly the result of a conductivity effects. The relaxational soft mode contribution is present as well but is small as compared to the conductivity contribution. Such huge conductivity is caused by a premelting phase, which is visible even at temperatures below the phase transition. Relaxational soft mode temperature behaviour is also different from classical ferroelectrics. Only change in the activation energy can be identified as a phase transition. Due to that contribution of this mode, the static dielectric permittivity also behaves completely different—it has minima at TC. Present results confirmed value of TC obtained from neutron scattering experiments. Obtained results are compared between NaNO3 and NaNO2. [ABSTRACT FROM AUTHOR]

Li(1 + x - y)Nb(1 - x - 3y)Ti(x + 4y)O3 ceramic system has been promising materials for LTCC application for their high dielectric constant, quality factor and low sintering temperature. In this paper, different kinds of additive were added to the so called “M phase” solution to further lower their sintering temperature. The effects of different content of B2O3, LiF on sintering character and microwave dielectric properties of LiNb0.6Ti0.5O3(x = 0.1, y = 0.1) ceramics were investigated as a function of sintering temperature and calcining time. LiF was chosen as compensation to Li loss during calcining and sintering procedure. According to experiment result, properly prolonged calcining time (8-10 h) favored the ordered growth of grain and the improvement of dielectric performance. [ABSTRACT FROM AUTHOR]

Microwave characterisation of dielectric materials is vital to implement the material in communication devices and circuits. The microwave characterisation parameters are the dielectric constant, loss tangent, Q0 × f0, temperature coefficient of frequency and temperature coefficient of permittivity. This paper examines the microwave characterisation data of four different dielectric materials. From several experiments on different dielectric materials, it has been concluded that the concept of using Q0 × f0 and temperature coefficient of frequency, as a material property will not reflect on material's fundamental behaviour. On the other hand, it has been interesting to note that the temperature coefficient of permittivity of a material is a constant irrespective of the measurement technique and hence it is a material parameter. The studies on temperature dependent permittivity will reveal the knack of a material to operate as a frequency stable circuit or device. [ABSTRACT FROM AUTHOR]

Microwave dielectric properties of the lithium contained ceramics with rock salt structure including LiFeO2, Li2ZrO3, Li3NbO4, Li2TiO3, and Li3Mg2NbO6 and Li3Zn2SbO6 have been investigated for the first time in this paper. It was found that all samples posses the dielectric constant in the range from10 to 25. The Q × f value increases in the sequence of LiFeO2, Li2ZrO3, Li3Zn2SbO6, Li3NbO4, Li2TiO3 and Li3Mg2NbO6. All samples exhibit negative value of temperature coefficient of resonant frequency except for Li2TiO3. Excellent microwave dielectric properties were obtained for Li3Mg2NbO6: εr = 16.8, Q × f = 79643GHz, τf = -27.2ppm/°C. [ABSTRACT FROM AUTHOR]

In this paper, ferroelectric Na0.5Bi0.5TiO3 (NBT, in short) was used as additives to improve the permittivities of Ba4.2(Sm0.9,Bi0.1)9.2Ti18O54 (BSBT, in short) solid solutions. X-ray diffraction (XRD) analysis did not reveal any second phases or modification of the BSBT crystal structure. Field emission scanning electron microscopy (FE-SEM) analysis showed typical columnar grains became more rod-like with the increasing amounts of NBT addition. Electron probe microanalyzer (EPMA) results revealed a change of second phases from BaTi4O9 to Ba-Sm-Bi-Ti-O solid solutions with a very long needle shape. The addition of NBT (≤10 wt. %) increased the relative permittivities remarkably while the Qf values decreased. The TCf values increased slightly with the increasing additions of NBT and the sintering temperatures. BSBT doped with 5 wt.% NBT additives exhibited excellent dielectric properties with εr = 90.1, Qf = 5450 GHz and TCf = 0.2 ppm/°C when sintered at 1320°C for 2 hours. [ABSTRACT FROM AUTHOR]

This paper investigated the resistivity and dielectric properties of manganese doped barium titanate sintered in pure nitrogen. The influence of variable doping concentration and Ba/Ti ratio on densification, microstructure, resistivity and dielectric properties was studied. A dielectric with permittivity of 1500 and low dissipation factor of 0.01 measured at 1 kHz, meeting the EIA X7R specification of the Electronic Industries Association standards was obtained in this study. Resistivity of materials sintered in pure nitrogen was 1011∼ 1012Ω cm. Ceramics sintered in pure nitrogen had higher resistivity than ceramics sintered in air, and the resistivity increased with Ba/Ti ratio increasing. [ABSTRACT FROM AUTHOR]

For the research on the LTCC(Low Temperature Co-fire Ceramic) applications, low temperature sintered ceramics have been extensively investigated. In this study, we have focused on the Li2CO3 doped (Ba,Sr)TiO3 and ZnBO doped (Ba,Sr)TiO3ceramics which have moderate dielectric properties such as high dielectric permittivity and low loss tangent. Until now, B2O3 has been commonly employed as the low temperature sintering aid. However, in this paper, we suggest Li2CO3 and ZnBO as alternative sintering aids to the B2O3. 1∼5 wt% of Li2CO3 or ZnBO was added to BST ceramics in order to reduce the sintering temperature. Li2CO3 doped BST and ZnBO doped BST ceramics were respectively sintered from 700°C to 1050°C and 750°C to 1250°C by 50°C to confirm the sintering temperature with different dopants concentrations. By adding Li2CO3 to the BST ceramics, the sintering temperature of BST ceramics was drastically lowered down to 900°C, whereas by introducing ZnBO dopants to BST, the loss tangent was decreased. From the XRD analysis, ZnBO doped BST ceramics have no pyro phase. 3 wt% Li2CO3 doped BST ceramics, which sintered at 900°C, have moderate relative dielectric permittivity of 1451 at 1 kHz, while 5 wt% ZnBO doped BST ceramics, sintered at 1100°C, have decreased dielectric permittivity of 1180 at 1 kHz. The loss tangent of ZnBO doped BST was decreased compared with that of BST. The loss tangent of ZnBO (1 wt%) doped BST was decreased down to 2.71 × 10-3 at 1 MHz. [ABSTRACT FROM AUTHOR]

This paper is a review article that emphasizes that dynamical processes of electromagnetic wave interaction with ferroelectrics proceed in such a way that characteristic frequencies of various excitations related to polarization lie in microwave range: i) a soft mode frequency in a number of displacive ferroelectrics on approaching the Curie temperature drops into the millimeter wave range or splits to components, the lower of which lies at microwaves and explains the static permittivity; ii) a frequency of relaxation soft mode in a number of order-disorder ferroelectrics lies also in the microwave range, and iii) relaxation of permittivity in relaxors and dipolar glasses also occurs at microwaves. Results of the complete dielectric spectra of the fundamental dielectric dispersion in the frequency range 1 MHz to 1012 Hz and its microscopic description in the most characteristic materials are presented and discussed. [ABSTRACT FROM AUTHOR]

The magnetic and dielectric properties of perovskite manganites R0.5Ca0.5MnO3 (R = Eu-Lu), which show charge ordering of the Mn-3d electrons below room temperature, have been investigated. Their dielectric constants were ∼ 1000-10000 at around room temperature. Inflections or peaks of temperature dependences of the dielectric constants were observed at around the charge-ordering temperatures. Analyses of tan δ for R = Eu-Lu and EXAFS spectra for R = Dy suggested that the dielectric properties of the present system are rooted in a special arrangement and transfer of the Mn-3d electrons. The two-peak structure of tan δ indicates that dielectric measurement can be used to observe homogeneity or inhomogeneity of sample, as mentioned in our previous paper on the ruthenium perovskite oxides. [ABSTRACT FROM AUTHOR]

This paper reports the structural and dielectric properties of Ba1 - xCaxTi1 - y (Zn1/3Nb2/3)yO3 ceramics with y is fixed to 0.2 and x = 0.2 and 0.3. Single-phase solid solutions of the simples were determined by X-ray diffraction. For the solid solution, BaTi1 - y(Zn1/3Nb2/3)yO3, the evolution of dielectric behaviour from a sharp ferroelectric peak (for y < 0.075) and to ferroelectric relaxor (for 0.075 < y < 0.2) was observed with increasing of Zn and Nb concentration but in this case the temperature of the maximum of dielectric permittivity Tm and Δ Tm are lowers. To modulate this relaxor character we have substitute the Ba by Ca to increase Tm and Δ Tm. [ABSTRACT FROM AUTHOR]

This paper focuses on the effect of back-etching on the electrical properties in (001)&(100) oriented Pb(Zr0.3Ti0.7)O3 (PZT30) thin films. The PZT30 thin films were deposited by chemical solution deposition (CSD) on a Pt/Ti/SiO2/Si substrate with different back-etching depth. The back-etching depth was controlled by changing the etching time in the range from 287 μ m to 98 μ m (residual Si thickness; TSi = 13-202 μ m). The residual stress in PZT30 thin film was estimated at the back etched part and the un-etched part by Raman analysis. In addition, the dielectric and ferroelectric properties in PZT30 thin film were measured to estimate the effect of the back-etching depth on the electrical properties. [ABSTRACT FROM AUTHOR]

In the present paper the optical spectra were measured by spectroscopic ellipsometry method in the range of 0.5-5.0 eV making use of a computer-controlled photometric ellipsometer with a rotating analyzer. The measurement data were traded in terms of a pseudodielectric function (PDF) in framework of the two-phase isotropic ambient-anisotropic homogeneous sample approximation. Anisotropic properties of the sample were revealed by performing the measurement with the sample at two orthogonal orientations with respect to the plane incidence. Two components of the dielectric tensor for crystal of orthorhombic symmetry were determined. The experimental spectra of the dielectric tensor components were approximated by the contributions of Laurence oscillators in order to determine the main optical transitions to the optical response. [ABSTRACT FROM AUTHOR]

The structural, dielectric and ferroelectric studies of SrBi2Ta2O9 (SBT) ferroelectric ceramics, partially substituted with wolframium (W) for tantalum (Ta), are reported in this paper. Polycrystalline samples of wolframium substituted SBT ceramics of compositions SrBi2(WxTa1 - x)2O9 (SBWT); x = 0.0-0.20 were synthesized by solid state reaction method. X-ray analysis confirm that the single phase layered perovskite structure is maintained up to x = 0.05. The microstructural studies reveal that the average grain size increases with the increase in W- content. Dielectric properties studied as a function of temperature at 100 kHz show an increase in Curie temperature over the composition range of x = 0.025 to 0.20. The dielectric loss reduces significantly with wolframium addition. The temperature dependence of dc conductivity of the samples vis-à-vis wolframium content exhibits the typical negative temperature coefficient of resistance (NTCR) and a decrease in conductivity by as much as two to three orders of magnitude is observed. The ferroelectric properties improved with W-doping and the maximum value of remanent polarization was observed for composition with x = 0.075. The observed results have been discussed in terms of contribution from the cation vacancies which are introduced into the lattice structure so as to compensate the charge imbalance due to donor doping. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This paper investigated the dielectrics properties of La-doped BaTiO3 sintered in pure nitrogen. The influence of variable doping concentration on microstructure and dielectric properties was studied. A new series of dielectrics with high permittivity of 160,000 ∼ 280,000 and low dissipation factor of 0.1 measured at 1 kHz, meeting the X8R specification of the Electronic Industries Association Standards (TCC within ± 15% from -55°C to +150°C) were obtained in this study. The doping mechanism of La-doped BaTiO3 was analyzed. The ceramics consisted of semiconducting grain cores with insulating grain boundaries, which is the origin of high permittivity. [ABSTRACT FROM AUTHOR]

In this work, varactor shunt switches (VSS) are utilized as test structures for characterization of ferroelectric thin films. The varactor shunt switch consists of coplanar waveguide input and output feed lines, and a shunt parallel plate varactor. The simplicity of the device structure and the ease of modeling the device allow one to match the experimental scattering parameters (S parameters) to the modeled results, and hence characterize the dielectric properties of the ferroelectric thin-film accurately. This paper illustrates the precise characterization of the ferroelectric thin-films using the VSS as a test structure. [ABSTRACT FROM AUTHOR]

Relaxors have a wide variety of industrial applications because of their high permittivity and piezoelectricity around room temperature. Although the microscopic mechanism of the relaxor behavior has not been fully elucidated yet, there are some fundamental developments in the experimental studies in the last decade, which are briefly reviewed in this paper with particular reference to pioneering works of Professor Ginzburg on phase transitions in ferroelectricity. [ABSTRACT FROM AUTHOR]

In this paper dielectric spectra of 0.6PMN-0.4PZN ceramic obtained from broadband dielectric spectroscopy is presented. Measurements revealed an unusual relaxor like nature. Two different processes in the dielectric spectra have been observed. High frequency, or short relaxation times, behaviour is typical for ferroelectric crystals. Longest relaxation times do not follow Vogel - Fulcher dependence, which is unusual for relaxors. [ABSTRACT FROM AUTHOR]

In this paper the method of calculation of two dimensional distribution function from dielectric spectra is presented. Simulation showed, that it is possible to obtain distribution function from experimental dielectric spectra. [ABSTRACT FROM AUTHOR]