Dielectric Constant Curve Research Articles

Preparation, structural, electrical, and ferroelectric properties of solid and lead zirconium titanate ink

The novelty of the work lies in the design and development of a significantly low-cost lead zirconate titanate (PZT) ink similar in its electrical properties to its original solid materials, which can be used for 3-D printing to print electronic circuits, shape memory, and devices quickly. The Zr/Ti=52/48 ratio was achieved during the solid-state reaction to create the PZT powder. XRD, FT-IR, and SEM characterized the synthesized material. The PZT powder was found to form in a tetragonal phase. The PZT powder was used to prepare PZT ink with a 13 % Wt/Wt solid content composition. The ink's rheological characteristics and physical properties, such as particle size distribution, surface tension, viscosity, and electrical properties, were studied. Dielectric properties like dielectric constant (ε/) and dielectric loss (ε") indicate the poly-dispersive nature of the material. The temperature-dependent dielectric constant (ε/) curve indicates relaxor behavior with a maximum at high temperatures. The poly-dispersive nature of the material was analyzed using Cole-Cole plots. The frequency dependence of AC conductivity follows the universal power law. The temperature dependence of dc-conductivity follows the Arrhenius law, with an activation energy of 0.14 eV at lower temperatures and 0.85 eV at higher temperatures. The electrical conductance study showed that PZT ceramic can be used in electronic circuits because of its high resistivity value and small temperature coefficient of resistance. The piezoelectric measurement displays d33 as 129 pC/N at room temperature.

Structural evolution, ferroelectric phase transitions, and dielectric behavior of Sn-doped Ba0.95Sr0.05TiO3 ferroelectric ceramics

ABSTRACT In this report, I studied the structural, morphological, and dielectric properties of new ferroelectric compounds prepared according to the formula Ba0.95Sr0.05Ti1-ySnyO3. The solid-state reaction method enhanced by a high-efficiency metal ball mill was used in the preparation process. The quantitative and qualitative analysis of the XRD patterns confirmed the crystallization of the samples y = 0.00, 0.05 in the tetragonal crystal system and the presence of the tetragonal and cubic crystal systems together in the samples y = 0.10, 0.14. Formation of BaSnO3 impurities in very low percentages in the doped samples. Their prevalence increases with increasing tin content, reaching 8.7% at the ratio y = 0.14. SEM images of the ceramic samples showed the formation of nano-ceramics with a high degree of condensation at the doping ratio y = 0.05. The dielectric analyses showed high thermal stability in the dielectric properties of the ceramic samples y = 0.05, 0.10, which was shown by the flatness of the dielectric constant curve over the entire temperature range studied, where this stability is attributed to the structure of the nano-grains that resist the ferroelectric-paraelectric phase transition. Furthermore, the dielectric properties were interpreted by accurately linking the dielectric measurements with the nano-structural and polar properties.

Double hysteresis (P-E) loops in the transparent composite containing BaTiO3 at room temperature

A transparent composite sample containing BaTiO3 was synthesized by using the melting quenching method. The presence of a glassy phase in this composite sample was detected through XRD analysis, and this was further confirmed by DSC study. TEM and SAED analyses provided evidence that the BaTiO3 nanoparticles/clusters are embedded within the borate glass matrix, establishing the composite nature of this sample. FTIR spectrum of the present sample revealed that the glass matrix is composed of two structural groups (BO3 with NBO’s, and BO4), along with the distinct groups for BaTiO3. XPS spectra of the present composite sample indicated the presence of more than one type of boron, barium, titanium and oxygen. DSC and dielectric studies of the present composite sample revealed the presence of the phase transition temperature (Tc). Dielectric constant (ɛr) and dielectric loss (tan δ) curves of the present composite sample displayed an anomaly peak in the vicinity of TC. The optical transmission spectrum of the present composite sample exhibit two transmission bands of Ti3+ (3d1) ions in tetragonal distorted sites. At room temperature, the present transparent composite sample exhibited double hysteresis loops for BaTiO3 at low electric fields. The results obtained can be used for the development of lead-free ferroelectric material.

The effect of A-site Mg substitution on energy-storage density and efficiency of Bi0.47Na0.47Ba0.06TiO3 ceramics by disordered induction

Lead-free dielectric ceramic capacitors are extensively studied for their environmental protection and excellent electrical properties. In this study, (1-x) Bi0.47Na0.47Ba0.06 TiO3-xMgTiO3 was synthesized by the classical solid-phase method. Perovskite materials usually have a complex structure, and the modification of the A-site and B-site doping can have a wonderful effect on the material. The effect of A-site Mg2+ doping on the phase structure and electrical properties of (1-x)BNBT-xMT was studied. Results showed that a wider optical band gap and a higher grain boundary density can be obtained by doping at the A-site, which greatly improved the breakdown electric field of the ceramics. X-ray diffraction, Raman scattering, transmission electron microscopy, and dielectric constant curves of (1-x)BNBT-xMT ceramics were also performed to characterize the transition between rhombohedral and tetragonal phases. The findings indicated that that doping at the A-site successfully induced the polar nanoregion, and the 0.94Bi0.47Na0.47Ba0.06TiO3-0.06MgTiO3 relaxation ferroelectric ceramics had high Wrec (5.82 J/cm3), stable frequency (Wrec = 2.53 J/cm3±3 %, 1–200 Hz), excellent temperature stability (Wrec≈2.37 ± 3 % J/cm3, 30–100 °C), and fast discharge rate (4μs). This work can provide ideas for the development of green and harmless dielectric capacitors with high charge/discharge rate and high energy-storage density.

Interface Structure, Dielectric Behavior and Temperature Stability of Ba(Mg1/3Ta2/3)O3/PbZr0.52Ti0.48O3 Thin Films.

Multilayer films can achieve advanced properties and a wide range of applications. The heterogeneous interface plays an important role in the performances of multilayer films. In this paper, the effects of the interface of Ba(Mg1/3Ta2/3)O3/PbZr0.52Ti0.48O3 (BMT/PZT) thin films on dielectric behavior and temperature stability are investigated. The heterogeneous interface structures are characterized by Auger electron spectroscopy (AES). The PZT-BMT interface is different from the BMT-PZT interface in thickness. For the PZT-BMT interface, the PZT thin films are diffused to the whole BMT layers, and the interface thickness is about 90 nm, while the BMT-PZT interface's thickness is only about 8.6 nm. The presence of heterogeneous interfaces can improve the performances of BMT/PZT thin films and expand their applications. The dielectric constant of BBPP thin films is significantly lower than BPBP thin films, while the dielectric loss is exactly the opposite. The more interfaces there are, the greater the dielectric constant. The relationship between the electric-field-dependent dielectric constant curve and the P-E curve is established. The equivalent interface barrier of the diode is used to show that the dielectric peaks under the positive and negative voltage are different. Similarly, heterogeneous interfaces show a certain improvement in dielectric tunability and temperature stability.

Remarkably minimized domain and elevated energy storage properties in Na0.48Bi0.48Ba0.04TiO3-based relaxor antiferroelectrics by interposing Bi(Mg2/3Ta1/3)O3

Lead-free dielectric capacitors have been embraced recently due to their tiny volume, large energy density and superfast charge–discharge speed. Here, a recoverable energy storage density of ∼ 10.73 J cm−3 and an efficiency of ∼ 80.5% were simultaneously revealed in traditional sintering (1 − x) (Na0.48Bi0.48Ba0.04TiO3)-xBi(Mg2/3Ta1/3)O3 (x = 0.16) ceramics (BNBT-0.16BMT) under an applied electric field of 540 kV cm−1 via disordering B-site ions and modifying the B-site cation ratio. Specifically, the disorder of B-site ions was found to alter the crystal structure, delaying maximum polarization. Phase switching between rhombohedral and tetragonal was characterized with transmission electron microscopy, Raman scattering and dielectric constant curves. Mg/Ta dopant was shown to cause electric charge mismatch and change dielectric anomaly peaks, leading to a large maximum polarization value. Finally, BNBT-0.16BMT stabilizes the relaxor antiferroelectrics (RAFE) system, with a significant broad frequency (0.5–120 Hz), broad temperature stability (20–160 °C), and excellent discharge performance (WD ∼ 5.23 J cm−3; Ea ∼ 350 kV cm−1). This preparation shows potential for broad application in dielectric capacitors.

Effect of Sr-doping on structural, morphological and dielectric properties of BaTi0.93Sn0.07O3 ferroelectric ceramics

In this report, we studied the Ba1-xSrxTi0.93Sn0.07O3 (x = 0.00, 0.10, 0.20, and 0.30) Perovskite ceramics produced by solid-state reaction (SSR) method and investigated their structural, morphological and dielectric properties by XRD, SEM, and LCR meter respectively. The Rietveld refinement of the XRD pattern confirms the samples crystallize in the Perovskite structure and transform from tetragonal for x = 0.0 to the co-existence of both cubic (Pm-3m) and tetragonal (P4mm) phases near room temperature for x ≥ 0.10. The Williamson-Hall (W–H) method has been used to determine the crystallite size and microstrains from the XRD peaks analysis, which showed the crystallite size value decreases with increased doping with Sr. The surface morphology shows the formation of ceramic grains with well-defined grain boundaries, as well as a decrease in grain size with an increase in the doping ratio. Moreover, the elemental ratio of doped ions was confirmed by EDS. The dielectric properties (έ, and tanδ) were studied as a function of temperature (20–150 °C) and a frequency (20 kHz - 3 MHz). The values of the dielectric constant έ decrease with the higher the frequency used. A diffuse phase transition was observed when doped with Sr. Where doping with Sr causes outstanding stability of έ values, which is evident by the flattening the dielectric constant curve, addition to increasing the dielectric constant values over range studied temperatures.

Magneto-electric effect in Y1-xRxFeO3 (R = Sm and Er) ceramics

In the present work, we synthesize a series of Y1-xRxFeO3R=Er,Sm&0.≤x≤1 polycrystalline compound by solid-state reaction method to study the A-site substitution effects on physical properties in YFeO3. The Rietveld refinement of X-ray diffraction analysis indicates that with Er3+ substitution, the lattice parameters have decreased, and more structural distortion has been shown compared to Sm3+ substitution. The obtained magnetic hysteresis loops reveal that Er3+ ions have induced an antiferromagnetic behavior in YFeO3 because of a reduction in the Dzyloshinskii-Moriya interaction. The Y1-xSmxFeO3 family, however, shows a weak ferromagnetic behavior. Furthermore, due to the spin reorientation (SR) transition, a distinct anomaly has been detected in the temperature dependence of Ac susceptibility and dielectric constant curves. With substituting Sm at the Y-site in the YFeO3 compound, SR transition happens at a temperature, TSR, in which the spin structure changes high-temperature Γ4 to Γ2 configuration, and therefore the starting and ending of the SR region depend on Sm concentration. Interestingly, we have observed a gigantic dielectric constant in Y0.7Sm0.3FeO3, Y0.5Er0.5FeO3, and Y0.25Er0.75FeO3. It, however, has demonstrated that Y0.7Sm0.3FeO3 is the only compound that shows a relaxor ferroelectric behavior. The observed peak in the temperature dependence of the dielectric constant has also described a magnetic transition temperature indicating the magneto-dielectric effect in our studied samples.

Short-range magnetic correlation, metamagnetism, and coincident dielectric anomaly in Na5Co15.5Te6O36

Here we explore the structural, magnetic and dielectric properties of Co based compound Na$_5$Co$_{15.5}$Te$_6$O$_{36}$ as a candidate of short-range magnetic correlations driven development of dielectric anomaly above N$\acute{e}$el temperature of ($T_N$=) 50 K. Low temperature neutron powder diffraction (NPD) in zero applied magnetic field clearly indicates that the canted spin structure is responsible for the antiferromagnetic transition and partially occupied Co form short range magnetic correlation with other Co, which further facilitates the structural distortion and consequent development of dielectric anomaly above antiferromagnetic transition. Additionally, the temperature dependent magnetic heat capacity and electron spin resonance measurements reveal the presence of short-range magnetic correlations which coincides with an anomaly in the dielectric constant vs temperature curve. Moreover, significant changes in the lattice parameters are also observed around the same temperature, indicating presence of noticeable spin-lattice coupling. Further, sharp jump in the magnetic field dependent magnetization clearly indicates the presence of metamagnetic transition and magnetic field dependent NPD confirms that rotations of Co spins with applied magnetic field are responsible for this metamagnetic phase transition. As a result, this transition causes the magnetocaloric effect to be developed in the system, which is suitable for the application in low temperature refrigeration.

Off-Stoichiometry Thiol-Ene Polymers: Inclusion of Anchor Groups Using Allylsilanes.

The use of polymers in silicon chips is of great importance for the development of microelectronic and biomedical industries. In this study, new silane-containing polymers, called OSTE-AS polymers, were developed based on off-stoichiometry thiol-ene polymers. These polymers can bond to silicon wafers without pretreatment of the surface by an adhesive. Silane groups were included in the polymer using allylsilanes, with the thiol monomer as the target of modification. The polymer composition was optimized to provide the maximum hardness, the maximum tensile strength, and good bonding with the silicon wafers. The Young's modulus, wettability, dielectric constant, optical transparency, TGA and DSC curves, and the chemical resistance of the optimized OSTE-AS polymer were studied. Thin OSTE-AS polymer layers were obtained on silicon wafers via centrifugation. The possibility of creating microfluidic systems based on OSTE-AS polymers and silicon wafers was demonstrated.

Exploring the Lunar Regolith's Thickness and Dielectric Properties Using Band‐Limited Impedance at Chang’E‐4 Landing Site

AbstractThe Yutu‐2 rover onboard China's Chang’E‐4 was the first to land in the Von Kármán crater on the lunar farside, where structural and dielectric properties may provide previously unknown clues to lunar formation and evolution. Based on the Lunar Penetrating Radar (LPR) with 500 MHz onboard the Yutu‐2 rover, we proposed a band‐limited impedance (BLIMP) inversion method to generate continuous dielectric 2‐D profiles with the help of dielectric constants retrieved from point reflectors (e.g., buried rocks), which provide low‐frequency information that may be lost or distorted in the LPR data pre‐processing. The dielectric constants retrieved from point reflectors were transformed from dielectric constant fitting curves, where these discrete dielectric constants were calculated using the hyperbolic fitting method. We estimated that the top fine‐grained regolith thickness along the rover path varies from ∼5.3 to ∼15.0 m in the first 27 lunar days of operation. The thickness variation could most likely be attributed to changes in ancient surface topography buried underground and ejecta from nearby craters. Compared to methods based on a singular dielectric constant, the estimated 2‐D dielectric profile in this study can reduce the uncertainties in lunar regolith thickness estimation, especially in the shallow layers. The BLIMP method and the estimated regolith thickness can improve our understanding of lunar subsurface structure and formation.

Influence of sintering temperature on electrical properties of Fe substituted NdCrO3 relaxor perovskite ceramic materials

Temperature-dependent dielectric properties of NdCr1-xFexO3 (0 ≤x≤1) (NCFO) perovskite nanocrystalline materials were successfully studied at 1 kHz, 10 kHz, 100 kHz, and 1 MHz selected frequencies. Temperature dependent real part of dielectric constant (ε′) curves of all samples exhibit step like relaxations. Capacitance (C) have been calculated for x = 0, 0.5, 1 samples of both 450 °C, 900 °C sintered systems at 1 kHz & 315 K and are found to be 4.5x 10-11 F, 1.5x 10-10 F, 3.7x 10-12 F; 1.4x 10-9 F, 2.6x 10-10, 9.3x 10-12 F respectively. Temperature variation real part of impedance (Z′), dielectric loss (tan δ) and imaginary part of modules (M″) plots have shown relaxor behavior. These plots obeyed Arrhenius law, and activation energies (Ea) are found to be in the order of 0.7–0.94 eV indicating semiconductor behavior. It is also noticed that ac conductivity (σac) is progressively increased with augment in temperature. σac have been estimated for x = 0, 0.5, 1 samples of both 450 °C and 900 °C sintered systems at 10 kHz & 315 K which are 4.5x 10-5 S/m, 1x 10-3 S/m, 1.4x 10-7 S/m; 1.8x 10-3 S/m, 1.2x 10-2 S/m, 1x 10-6 S/m respectively. High sintered (900 °C) samples possess high grain growth, and densification, which leads to significant structural and structural and electrical properties. Significant results of samples are suitable for high-power-density capacitors and microwave applications.

Influence of glycine and ammonium dihydrogen phosphate on their growth and characterization of l-Alanine single crystal for nonlinear optical applications

A non-linear optical single crystal of l-Alanine has been synthesized using the glycine and l-Alanine doped with various concentration of ammonium dihydrogen phosphate (ADP) (0.25, 0.30, 0.35 & 0.45 M%) through slow evaporation technique at ambient temperature. The characterization of single and powder XRD crystal reveals their crystal structure, lattice parameters and various reflecting planes. Different vibration modes of functional groups in the crystal can be identified by FTIR. The optical transmission property and their corresponding band gap value were determined by UV–Vis study. Thermal stability and melting point were investigated using TG-DTA analysis. Vickers micro hardness study used to find out the mechanical strength and Meyer's index value ‘n’ of the crystal. Dielectric constant and dielectric loss response curves were plotted over the frequency range from 50 Hz to 1 MHz. The existence of nonlinear property produces the SHG efficiency that is 0.75 times higher than KDP through the Kurtz-Perry powder technique.

Effect of Mn-doping on the morphological and electrical properties of (Ba0·7Sr0.3) (MnxTi1−x)O3 materials for energy storage application

Lead-free (Ba0·7Sr0.3) (MnxTi1−x)O3 (x = 0.0, 1.0, 2.0, 4.0, 6.0, and 8.0%) ceramics were effectively synthesized by the sol-gel process. XRD and Raman spectroscopy confirm the single-phase perovskite structure with tetragonal symmetry, for all compositions. An in-depth analysis of the chemical composition and thermochemistry of the ceramics was carried out via FT-IR and TG-DTG. Morphological analyses of the samples revealed that doping Mn at higher concentrations suppresses the grain size and grain growth rate. The dielectric properties increased first and then decreased with increasing Mn content. The ferroelectric properties represented similar trend in polarization and energy storage efficiency as showed in dielectric properties. 2% Mn-doped sample exhibits the best dielectric and energy storage performance which is attributed to increased densification and grain size effects. Dielectric anomaly caused by defect dipole polarization was observed in temperature-dependent dielectric constant curves, for 6% and 8% Mn-doped samples. This study is helpful to establish the relationship between the structure, morphology, dielectric and ferroelectric properties of Mn substituted Ba0·7Sr0·3TiO3 ceramics.

The antiferromagnetic ordering and metamagnetic transition induced magnetodielectric effect in Dy2Cu2O5

Ferroelectricity and magnetism seldom coexist due to mutual exclusiveness. Recent attempts have been made to achieve the coexistence of ferroelectricity and magnetism in polar magnets. In this paper, we investigated the magnetic properties, dielectric relaxation, and magnetodielectric (MD) effect of polar Dy2Cu2O5 ceramic. At the antiferromagnetic ordering temperature, the dielectric constant (ɛ) curves exhibit a spontaneous change in slope, indicating strongly coupled charge and spin degrees of freedom. With increase in the magnetic field intensity, the simultaneous suppression of the dielectric anomaly and the antiferromagnetic transformation demonstrates the existence of the MD effect. It is important to note that ɛ varies nonmonotonically with the magnetic field. Below the magnetic ordering temperature, ɛ increases continuously before the metamagnetic transition and then decreases after that. The results are discussed in terms of the magnetic field-induced change of spin configuration and spin–phonon coupling. Moreover, two dielectric relaxation-related steps are observed, which are correlated with the electrons hopping within and among the zigzag chains of Cu2+, respectively. This work helps understand the dielectric behavior and the MD effect in materials with complicated spin structures.

Determination of the atomic cohesive energy and Debye temperature from thermal stiffening of the dielectric constant of semiconductors

From the perspective of bond-order-length-strength correlation, we have formulated the thermally stiffened dielectric constant and refractive index for semiconductors. It is clarified that: (i) The dielectric constant and refractive index of semiconductors turn from non-linear to linear thermal stiffening at one third of its Debye temperature; (ⅱ) The Debye temperature determines the width of the non-linear part and the reciprocal atomic cohesive energy determines the slope of linear part at high temperatures of the dielectric constant and refractive index curves.

Swift Heavy ion irradiation effects on dielectric constant and dielectric loss in poly (ether ether ketone) (PEEK)

The dielectric constant (ε') and dielectric loss (ε״) of pristine and C5+ (70 MeV) ion irradiated samples of the PEEK have been investigated with the variation of temperature at different frequencies (100 Hz, 1 kHz, 10 kHz and 100 kHz). The maxima are obtained around 170 oC in dielectric constant (ε') vs. temperature (T) curve. This relaxation is linked with the movement of ketone (>C=0) dipoles linked to the main chain. The irradiation of polymers increases the orientational polarization due to increase in number of dipoles with fluence. The increase in dielectric constant (ε') and dielectric loss (ε'') is attributed to chain scissioning at higher fluence which results in an increase of free radicals and unsaturations. Copyright © 2018 VBRI Press.

Structure and Dielectric Behavior of Yb2O3-MgO Co-Doped 0.92BaTiO3-0.08(Na0.5Bi0.5)TiO3 Ferroelectric Relaxor.

Dielectric properties and structure of 0.015Yb2O3-xMgO doped 0.92BaTiO3-0.08(Na0.5Bi0.5)TiO3 ceramics with x = 0.0–0.025 have been investigated. As Yb2O3-MgO was added into the BT-NBT, the phase changes from tetragonal to pseudo-cubic, with the tetragonality c/a decreases from 1.011 to 1.008 and XRD peaks broadened. The combined study of XRD and TEM image revealed a formation of core–shell structure in grains with core of 400–600 nm and the shell of a thickness 60–200 nm. There is a slowly phase transition against temperature from the variable temperature Raman analysis. The ferroelectric relaxor peak of BT-NBT decreases from ~4000 to ~2000 and a new broad dielectric peak with an equivalent maximum (εr′~2300) appears in the temperature dependent dielectric constant curve (εr′-T), which produces a flat εr′-T curve. Sample 0.92BaTiO3-0.08(Na0.5Bi0.5)TiO3-0.015Yb2O3-0.005 MgO and 0.92BaTiO3-0.08(Na0.5Bi0.5)TiO3-0.015Yb2O3-0.01MgO give a εr′ variation within ±14% and ±10% in 20–165 °C. The core–shell microstructure should take account for the flattened εr′–T behavior of these samples.

Effect of BaTiO3 on the Properties of PVC-Based Composite Thick Films.

Flexible PVC/BT (Polyvinyl chloride/Barium Titanate) composite thick films with (0–30%) volume fractions of BaTiO3 were fabricated via the solution casting method. The effects of BaTiO3 filler on the phase, microstructure and dielectric properties of composite films were investigated. The XRD results revealed that BT particles are embedded in the PVC matrix with no chemical reaction taking place between the two phases. It was observed that the glass transition temperature of PVC had increased with the addition of BT. The frequency dispersion in the dielectric constant versus temperature curves indicated the relaxor nature of the composites. The dielectric constant (εr) measured at 40 °C, increased from 7.6 for pure PVC to 16.1 for 30% of BaTiO3 content in PVC polymer matrix. It is suggested that BaTiO3 ceramic powder enhanced the dielectric properties of PVC and may be used as a flexible dielectric material.

Multiferroic properties in [formula omitted] ceramics

The effect of Er3+ substitution on the physical properties of SmFeO3 was studied through magnetic and electrical measurements. The X-ray diffraction patterns of Sm1-xErxFeO3 samples showed that the lattice constants decrease with increasing Er content. As a result, the distortion of Er -doped SmFeO3became significant. The magnetic hysteresis loops of samples indicate that the antiferromagnetic trend increases with Er concentration. The anomaly in Ac susceptibility (χ) and dielectric constant curves for Sm1-xErxFeO3 provided evidence for occurring spin reorientation transition (SRT) in these compounds and are also observed the gradual decrease in SR temperature with increasing Er3+ions. Furthermore, the electrical measurements exhibited a considerable enhancement in the dielectric constant. Sm0.3Er0.7FeO3 is the only compound that presented a colossal dielectric constant (CDC) (103) at room temperature which is attributed to relaxor-ferroelectrics. Likewise, the appearance of magnetic and ferroelectric hysteresis loops indicated the coexistence of magnetism and ferroelectricity.