Temperature Dependence Of Dielectric Permittivity Research Articles

Synthesis and Dielectric Characterization of a New Relaxor Solid Solution of (1 − x)Pb(Mg1/3Nb2/3)O3-xBi(Zn1/2Ti1/2)O3

Ceramics of a new solid solution, (1 − x)Pb(Mg1/3Nb2/3)O3-xBi(Zn1/2Ti1/2)O3 [(1-x)PMN-xBZT], have been prepared (with x = 0.05–0.30) and investigated for their structure and relaxor ferroelectric properties. The structure remains pseudocubic (or rhombohedral) up to the solubility limit of x = 0.275. All the compositions studied show broad and diffuse peaks in the temperature and frequency dependences of dielectric permittivity, indicating typical relaxor behavior. The temperature dependences of dielectric permittivity for all the samples studied follow an empirical quadratic law that describes the high temperature slope of the permittivity. The diffuseness in the dielectric peaks was found to increase linearly with the increasing amount of BZT, which can be attributed to the increase in chemical disorder in the system.

Multiferroic ceramics Pb(Fe1/2Nb1/2)O3 doped by Li

We present the results of obtaining and investigating multiferroic ceramics Pb(Fe1/2Nb1/2)O3 (PFN) and PFN doped by various amounts of Li (PFN:Li). Ceramics have been obtained from oxides by two-step synthesis. For obtained samples the X-ray diffraction patterns, microstructure, DC electric conductivity, the temperature dependencies of dielectric permittivity and dielectric losses, electromechanical properties and hysteresis loops have been investigated. Obtained results have shown that the introduction of Li decreases electric conductivity and improves dielectric and electromechanical parameters important for applications.

A Simulation of Dielectric Spectroscopy of Some Ferroelectric Materials

Temperature dependent dielectric permittivity is a crucial parameter in determining the physical property of ferroelectric materials. A method of using temperature to predict the dielectric permittivity of some ferroelectric materials is studied. The object of this work is to search for the applicable method of using temperature to predict the dielectric permittivity and control the transition of some ferroelectric materials from ferroelectric phase to paraelectric phase. A typical numerical method is highlighted and discussed in light of the potential applications to the various experimental results. The simulations agree very well with the observed spectroscopy of twelve curves for dielectric permittivity versus temperature. The minimum value of correlation coefficients between actual and calculated data is 0.98. The maximum data of mean relative errors is 6.98%. This study may make a contribution to the theoretical and the practical aspects of the ferroelectric materials.

Nanostructured ceramics of BiScO 3–PbTiO 3 with tailored grain size by spark plasma sintering

The combination of non-conventional methods of synthesis (mechanosynthesis) and sintering (SPS) has been used for the preparation of nanostructured BiScO3–PbTiO3 ceramics with tailored grain size. The key to control grain growth in the nanoscale is to achieve a significant densification during initial stages of the SPS, mainly by particle rearrangement under pressure, before thermally activated processes are triggered. The temperature dependence of dielectric permittivity suggests that the ferroelectric transition might have vanished for the material with the smallest grain size.

Structural and Dielectric Studies of NaNbO3-A0.5Bi0.5TiO3 (A-Li,Na,K) Solid Solutions

Structural and dielectric studies of NaNbO3 solid solutions with ternary perovskites A0.5Bi0.5TiO3 (A–Li, Na, K) have shown that while the evolution with x of the temperature dependence of dielectric permittivity, phase transition temperatures and structural parameters for (100-x)NaNbO3–(x)Na0.5Bi0.5TiO3 system are typical of the group II NaNbO3-based solid solutions, the properties of (100-x)NaNbO3–(x)A0.5Bi0.5TiO3 (A–Li, K) systems combine the features typical of both group II and group I solid solutions. This difference is explained assuming that the latter two systems are actually ternary solid solutions of the NaNbO3-Na0.5Bi0.5TiO3-ANbO3 (A–Li, K) type.

Domain wall contributions in Pb(Zr,Ti)O3 ceramics at morphotropic phase boundary: A study of dielectric dispersion

The dielectric properties of undoped, Nb-, and Fe-doped Pb(Zr,Ti)O3 ceramics with composition near morphotropic phase boundary were investigated in the frequency range from 1 MHz to 20.2 GHz at room temperature. Temperature dependences of dielectric permittivity ε′ and loss ε″ are measured at 100 kHz from 50 to 300 K and around 13.4 GHz from 100 to 300 K. These measurements permit estimation of the upper limit of the intrinsic permittivity and lower limit of the extrinsic contributions to the permittivity as a function of temperature. The extrinsic contributions account for more than 50% of the quasistatic dielectric permittivity in studied samples.

Layered Aurivillius compound: Synthesis, characterization and electrical properties

In the present study, sol–gel citrate route was utilized to synthesize BIALVOX (Bi 2Al x V 1− x O 5.5− x− δ ) in the composition range 0 ≤ x ≤ 0.20. Powder X-ray diffraction and simultaneous thermogravimetric and differential thermal analyses confirmed that the calcination of BIALVOX xerogels is fully completed at around 500 °C after 3 h of thermal treatment. It has been found that the stabilization of highly conducting γ-phase takes place for x ≥ 0.10. AC impedance spectroscopic investigation suggested that the charge accumulation at grain boundaries is more pronounced as compared to that at grain interiors. However, the maximum electrical conductivity (7.73 × 10 −5 S cm −1) was noticed for BIALVOX.13 at 300 °C. The temperature dependence of dielectric permittivity was also reported.

Phase diagram and dielectric properties of ferroelectric ceramics [formula omitted

Ferroelectric ceramics Pb 2− x K 1+ x Li x Nb 5O 15 (PKLN), with 0 < x < 1.5 , having the tetragonal tungsten bronze (TTB) structure, were synthesized using a solid-state reaction and characterized by X-ray diffraction. The temperature dependence of dielectric permittivity was measured from 35 to 550 °C in the frequency range from 20 Hz to 1 MHz. These measurements permit us to present the phase diagram of this family and the evolution of the transition temperature T C as function of the chemical composition.

Structure and physical properties of nickel manganite NiMn 2O 4 obtained from nickel permanganate precursor

In this paper we present the structural, magnetic and dielectric properties of ceramic nickel manganite NiMn 2O 4+ δ produced by using nickel permanganate Ni(MnO 4) 2 xH 2O as a precursor. We have characterized the NiMn 2O 4+ δ stoichiometry using quantitative energy-dispersive analysis of X-rays and thermal gravimetry under reducing conditions. Increased oxygen and Mn 4+ contents were detected. X-ray diffraction and Rietveld refinement of X-ray data were carried out. Temperature dependent magnetization measurements were performed and the ferri-magnetic transition was identified at ≈100 K. The ferri-magnetic moment was found to be ≈1 μ B and hysteretic magnetization vs applied field curves were obtained. Dielectric properties were measured using impedance spectroscopy. Two dielectric relaxation processes were detected, which were associated with grain boundary and bulk contributions. The Arrhenius plots of resistivity and the temperature dependent dielectric permittivity were obtained for the two relaxations by means of an equivalent circuit model based on a series of two parallel RC elements.

Diffuse phase transition and dielectric study in Ba0.95Ca0.05TiO3 ceramic

Abstract Temperature and frequency dependent dielectric permittivity of Ba 0.95 Ca 0.05 TiO 3 ceramic has been studied in the temperature range of 40–250 °C at the frequencies, 1, 10, 100 kHz and 1 MHz. Diffuse phase transition and frequency dispersion are observed in the permittivity vs. temperature plots. This has been attributed to the occurrence of relaxor ferroelectric behavior. The observed relaxor behavior has been quantitatively characterized based on the phenomenological parameters. The value of the dielectric constant at higher frequencies markedly dropped. Such a marked drop in the value of the dielectric constant at higher frequencies can be explained in terms of interfacial polarization. The build-up of charges at the grain–grain boundary interface is responsible for large polarization, therefore, the high dielectric constant at lower frequencies.

Dielectric properties of liquid-crystalline copolymers with side cyanobiphenyl groups and acrylic acid units

Dielectric properties of a number of liquid-cry stalline comb-shaped copolymers with different ratios of side-chain mesogenic cyanobiphenyl groups and acrylic acid units are studied. In the electric-field frequency range 300 Hz-100 MHz, temperature dependences of dielectric permittivity are obtained for nematic and isotropic phases. The times of relaxation and the energies of activation for processes responsible for dielectric-permittivity dispersion are measured. The quantitative relationship between the dielectric characteristics and the content of acrylic acid units in the copolymer is established.

Synthesis, characterization, and electrical conductivity of new Aurivillius-type oxide-ion conductor

A new oxide-ion conductor of Aurivillius family with a general formula Bi2AlxV1 − xO5.5 − x − δ; 0 ≤ x ≤ 0.20 (BIALVOX) was synthesized by the sol-gel citrate route. Powder X-ray diffraction and simultaneous thermogravimetric and differential thermal analyses confirmed that the calcination of BIALVOX xerogels is fully completed at around 500°C after three hours of thermal treatment. It has been found that the β-orthorhombic phase is stabilized with compositions x ≤ 0.07, whereas the stabilization of the γ′-phase takes place for x ≥ 0.10. AC impedance spectroscopic investigation suggested that the charge accumulation at grain boundaries is thermally activated process. However, the maximum electrical conductivity (7.73 × 10−5 S cm−1) noticed for BIALVOX.13 at 300°C was attributed to the maximum vacancy concentration in the equatorial planes, responsible for the ion diffusion through the structure. This has been further evidenced by the temperature dependence of dielectric permittivity.

A New Main Group Metal Coordination Polymer: Synthesis, Structure, and Dielectric Constant Property of [Na(C6H4N5)(H2O)2]n

AbstractThe reaction of NaOH with 4‐(2H‐tetrazol‐5‐yl)pyridine affords the first tetrazole‐pyridine sodium coordination polymer with chain structure, [Na(C6H4N5)(H2O)2]n (1). The compound could be characterized by single‐crystal X‐ray diffraction analysis. The temperature dependence of dielectric permittivity remains unchanged almost within the measured temperature range of 80 K to 270 K at 1 &lt;SC&gt;MH&lt;/SC&gt;z, and the frequency dependence of the permittivity showed rapidly drops from 31.5 to 4.3 within the measured frequency range of 200 to 1 MHz at room temperature.

Dynamic magneto-electric multiferroics PZT/CFO multilayered nanostructure

Highly oriented PbZr0.53Ti0.47O3/CoFe2O4(PZT/CFO) multilayered nanostructures (MLNs) were grown on MgO substrate by pulsed laser ablation using La0.5Sr0.5CoO3 (LSCO) as conducting bottom electrode. The effect of various PZT/CFO (PC) sandwich configurations having three, five, and nine layers while maintaining total thickness of PZT and CFO be identical has been systematically investigated. X-ray diffraction (XRD) and micro-Raman spectra revealed the existence of pure PZT and CFO phases without any intermediate phase. Intact MLNs were observed by transmission electron microscopy (TEM) with little inter-diffusion near the interfaces at nano-metric scale without any impurity phase. Impedance spectroscopy, modulus spectroscopy, and conductivity spectroscopy were carry out over a wide range of temperatures (100–600 K) and frequencies (100 Hz–1 MHz) to investigate the grain and grain boundary effect on electrical properties of MLNs. Temperature dependent real dielectric permittivity and dielectric loss illustrated step-like behavior and relaxation peaks near the step-up characteristic, respectively. Cole–Cole plots indicate that most of the dielectric response came from the bulk (grain) MLNs below 300 K, whereas the grain boundary and the electrode–MLNs effects are prominent at elevated temperatures. The dielectric loss relaxation peak shifted to higher frequency side with increase in temperature, it was out of the experimental frequency window above 300 K. Our Cole–Cole fitting of dielectric loss spectra indicated marked deviation from the ideal Debye-type of relaxation, which is more at elevated temperature. Master modulus spectra supported the observation from the impedance spectra; it also indicated that the magnitude of the grain boundary compared to grain becomes more prominent with increase in number of layers. We have explained these electrical properties of MLNs by Maxwell–Wagner type contributions arising from the interfacial charge at the interface of the ML structures. Three different types of frequency dependent conduction processes were observed at elevated temperatures (>300 K), which fitted well with the double power law, \( \sigma \left( \omega \right) = \sigma \left( 0 \right) + A_{1} \omega^{{n_{1} }} + A_{2} \omega^{{n_{2} }} , \) indicating that the low frequency (<1 kHz) conductivity may be due to long-range ordering (frequency independent), mid frequency conductivity (<10 kHz) may be due to short-range hopping, and high frequency (<1 MHz) conduction due to the localized relaxation hopping mechanism. Ferroelectric polarization decreased slowly in reducing the temperature from 300 to 200 K, with complete collapse of polarization at ~100 K, but there was complete recovery of the polarization during heating, which was repeatable over many different experiments. At the same time, the temperature dependent remanent magnetization of the MLNs showed slow enhancement in the magnitude till 200 K with three-fold increase at 100 K compared to room temperature. This enhancement in remanent magnetization and decrease in remanent ferroelectric polarization on lowering the temperature indicate temperature dependent dynamic switching of ferroelectric polarization. The magnetic and ferroelectric properties of MLNs were quite different compared to individual layers suggesting its improper ferroelectric characteristics. The fatigue test showed almost 0–20% deterioration in polarization. Fatigue and strong temperature and frequency dependent magneto-electric coupling suggest MLNs utility for Dynamic Magneto-Electric Random Access Memory (DMERAM).

Lattice parameters and dielectric properties of (1 − x)Bi(Mg1/2Ti1/2)O3 · xBiCoO3 perovskite solid solutions

(1 − x)Bi(Mg1/2Ti1/2)O3 · xBiCoO ceramics have been prepared at high pressures (6 GPa) and temperatures (1370–1570 K). Perovskite solid solutions have been obtained in the composition ranges 0 0.8) has a tetragonal structure (sp. gr. P4mn). In the range 0.6 < x < 0.8, the ceramics consisted of the two perovskite phases. The lattice parameters of the solid solutions with x < 0.6 are linear functions of composition. The dielectric properties of the orthorhombic solid solutions have been studied using impedance spectroscopy. The temperature dependences of dielectric permittivity ɛ′ and dielectric loss tanδ exhibit different behaviors at low and high temperatures. With increasing x, the boundary between these regions shifts from about 450 to 300 K. At high temperatures, both ɛ′ and tanδ rise steeply. The dc conductivity of the solid solutions with x < 0.6 exhibits Arrhenius behavior. The activation energies for charge transport in the ceramics studies are presented.

The Dielectric Characteristics of Screen Printed SrTiO3-Epoxy Composite Thick Films on the Cu Plate PCB Substrates

Novel electronic devices require higher performance and miniaturization. Due to the increased demands for the high density of passive components in the mobile system, integration of passive components in the inner layers of multi-layer substrates has been actively investigated. In this paper, we studied on SrTiO3-epoxy composites thick films for embedded capacitor applications. SrTiO3-epoxy composites were employed to explore its feasibilities of embedded capacitors applications. We have investigated the frequency dependent dielectric permittivity and the temperature dependent dielectric permittivity of SrTiO 3 -epoxy composite thick film metal-insulator-metal (MIM) capacitors. As the amount of epoxy resin was increased, the dielectric permittivity of composites was decreased. In temperature dependent dielectric permittivity characteristics, however, the dielectric permittivity was increased with the elevated temperature. We will show and discuss the leakage current density (j) – electric field (E) characteristics of SrTiO 3 -epoxy composite thick films.

Dielectric properties of high‐Tc ceramics based on BaTiO3 with (111) texture characteristics

Abstract0.94BaTiO3–(0.06–x)Bi0.5Li0.5TiO3–x Bi0.5Na0.5TiO3 (abbreviated as BT–BLT–BNT with x = 0, 0.015, 0.03, 0.045, 0.06) ceramics were prepared by the traditional ceramic processing route. The structure, dielectric and ferroelectric properties of the samples were investigated by X‐ray diffraction, the temperature dependence of dielectric permittivity, and hysteresis loop measurements. These results showed that all compositions have the perovskite tetragonal phase structure, and the phase‐transition temperature Tc is increasing with increasing x, the Tc is 163 °C for x equal 0.06; and the samples have good ferroelectric properties with lower coercive field and higher remanent polarization. BT–BLT–BNT ceramics prove to be a promising candidate for high‐Tc lead‐free ceramics. (© 2009 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Large electric-field-induced strain in Bi0.5Na0.5TiO3–Bi0.5K0.5TiO3 solid solution single crystals

Single crystals of ferroelectric (1−x)Bi0.5Na0.5TiO3–xBi0.5K0.5TiO3 (BKT) solid solution with rhombohedral structure were grown by flux method in the composition range of 0&amp;lt;x&amp;lt;0.14. The polarization hysteresis, electric-field-induced strain, and temperature dependence of dielectric permittivity were investigated along the [100]cubic direction. Although small substitution of BKT suppressed the remanent polarization from 38 μC/cm2 at x=0 to about 15 μC/cm2 at x&amp;gt;0.02, piezoelectric strain constant (d33) was enhanced with increasing x up to 297 pm/V at x=0.14.

Formation of Ferroelectric Nanostructures in (As2S3) 100 − x (SbSI) x Glassy Matrix

The structure and dielectric properties of (As 2 S 3 ) 100 − x (SbSI) x glasses and their transformation during the heat treatment have been investigated. It has been determined that all glassy alloys have a microgeterogeneous structure. It has been shown that anomalies on the temperature dependences of dielectric permittivity ϵ and tg δ are connected with the transition of glasses into a polar state followed by their crystallization. The crystallization of glasses is accompanied by a sharp increase in dielectric parameters conditioned by the formation of nanocrystalline inclusions in the glassy matrix which have ferroelectric properties. The structure arising in (As 2 S 3 ) 100 − x (SbSI) x (50 < x < 100) glass matrix during its crystallization corresponds to that of crystalline SbSI. The size of crystalline inclusions and dielectric permittivity value of ferroelectric glass-ceramic depend on the heat treatment conditions.

Lorentz-type relationship of the temperature dependent dielectric permittivity in ferroelectrics with diffuse phase transition

The temperature dependence of the dielectric permittivity of perovskite Ba(ZrxTi1−x)O3 solid solutions, PbMg1/3Nb2/3O3 relaxor, and BaTiO3 ferroelectric ceramics was measured. It is found that a Lorentz-type law can be used to describe the dielectric permittivity of either the normal ferroelectrics with or without diffuse phase transitions (DPT) or the typical ferroelectric relaxors. The ferroelectric DPT can be well described by just one fitting process using the Lorentz-type law, while the relaxor ferroelectric transition needs two independent fitting processes. The Lorentz-type law fails at the low temperature side of the dielectric maximum of a first-order ferroelectric phase transition. Above the transition temperature, the dielectric curves of all the studied materials can be well described by a Lorentz-type law.