Dielectric Properties Of BaTiO3 Research Articles

Enhanced densification and dielectric properties of BaTiO3 through a cold-sintering pre-treatment

Enhanced densification and dielectric properties of BaTiO3 through a cold-sintering pre-treatment

Dielectric properties of BaTiO3 and Ba0.95Ca0.05TiO3 sintered in a reducing atmosphere

The dielectric materials utilized in high-performance barium titanate-based base-metal electrode multilayer ceramic capacitors (BME MLCCs) must satisfy stringent criteria such as high dielectric constant, low dielectric loss, high insulation resistivity, and reliability. In this investigation, the effects of raw materials, BaTiO3 (BT), and Ba0.95Ca0.05TiO3 (BCT) on densification, microstructure, and dielectric behavior were explored by introducing acceptor and rare earth elements. The findings revealed that BCT could attain densification at a lower sintering temperature of 1275 °C than BT. Moreover, BCT samples displayed relatively smaller grain sizes, resulting in a greater number of grain boundaries, which in turn increased the insulation resistivity. BCT had a lower oxygen vacancy concentration, thus resulting in lower leakage currents at high temperatures than BT. Substituting BCT for BT resulted in higher activation energies for conductivity in the core, shell, and grain boundary. This investigation demonstrates that BCT can enhance the dielectric properties, insulation resistance, and reliability of the BME MLCCs.

Effect of yttrium (Y) substitution on the structure and dielectric properties of BaTiO3

As the rate of application of multilayer ceramic capacitors (MLCCs) in small electronic devices increases, the use of the raw material barium titanate (BaTiO3) with a small particle size and excellent dielectric properties becomes needed. Due to the size effect, small-sized BaTiO3 generally has a cubic phase structure with a low dielectric constant, which limits its use in MLCCs. We report the preparation of small cubic phase Y-doped BaTiO3 (BYT) nanoparticles by a hydrothermal method and the preparation of highly dielectric tetragonal phase BYT ceramics based on this method. XRD and Raman analysis showed that the BYT nanoparticles are in substable cubic phases. The particle size of the BYT nanoparticles, measured by TEM, XRD, and BET, was approximately 35 nm. The dielectric properties of the BYT ceramics were tested by an impedance analyzer, and the dielectric constant of the BYT ceramics was 7547 when the Y3+ doping amount was 0.5 mol%. In addition, the substitution mechanism of Y3+ doping in BaTiO3 crystals was proposed from XPS and EPR analysis. The results demonstrate for the first time that the 50 nm cubic phase BaTiO3 powder can meet the needs of next-generation high-capacity MLCCs. This work provides a reference for small cubic phase BaTiO3 as a dielectric material for high-capacity MLCCs.

Tuning the microstructure of BaTiO3@FeO core-shell nanoparticles with low temperatures sintering dense nanocrystalline ceramics for high energy storage capability and stability

A BaTiO3@FeO nanoceramic was successfully fabricated by chemical coating technique under sintering and achieved high energy storage capability. The FeO layer was coated onto BaTiO3 nanoparticles by sol-precipitation method. The structures, dielectric properties and energy storage capability of ceramics were systematically investigated. A high densification and nano-scale crystalline were observed after low temperatures sintering by this chemical coating technology and the grain size maintained about 70 nm. This chemical coating method is contributed to obtain dense nanocrystalline ceramics, benefiting to enhance the breakdown strength and energy storage density. The dielectric properties of BaTiO3@%FeO nanoceramics exhibit good temperature (−55 to 125 °C) and frequency(1 Hz–1 MHz) stability, indicating the fine dielectric quality of the ceramics. The BaTiO3@3%FeO nanoceramics present a high discharge energy storage density of 1.50 J cm−3 at 300 kV/cm-1 with a high energy storage efficiency about 88%. Moreover, the advanced energy storage properties with fast discharge features (τ0.9< 1.5 μs), prominent thermal stability (25–120 °C) and high cyclic stability (up to 1 × 105 times) were achieved in the BaTiO3@FeO nanoceramic. This nanoceramic prepared via the chemical coating could be a potential material for energy storage capacitor application.

Multi-phase coexistence and temperature-stable dielectric properties in BaTiO3/ZnO composite ceramics

BaTiO3:100xZnO composite ceramics with different ZnO particle sizes were prepared by using a conventional solid-state method. Phase constitution, microstructure and dielectric properties of BaTiO3:100xZnO composite ceramics are investigated. Compared to micrometer scaled ZnO particles, nanometer scaled ZnO particles tend to agglomerate at lower ZnO contents in the BaTiO3:100xZnO composite ceramics. The introduction of ZnO in BaTiO3 leads to the reduction of grain size, decrease of the tetragonality and shift of phase transition temperature. The optimum composition is BaTiO3 with 20 wt. % nanometer scaled ZnO particles, which has stable permittivity and low dielectric loss from -100 to 160 °C. The stable dielectric properties are proposed to be beneficiated from the stress induced multi-phase coexistence.

Dielectric properties and microstructure of BaTiO3-SiO2 nanocomposites using vacuum treated barium titanate nanoparticles

Effect of vacuum treatment on the microstructure and dielectric properties of BaTiO3 (BT)-SiO2 nanocomposites is systematically studied using BT nanoparticles with a process of vacuum treatment, and coated with a SiO2 layer by a wet chemical process. It is found that the vacuum treatment induced not only the oxygen vacancies but also permanent changes in the crystal structure of nanocomposites. Comparing with the nanocomposites sintered from untreated BT nanoparticles, the nanocomposites sintered from vacuum treated BT exhibit a significantly higher dielectric constant, a lower loss and, therefore, a higher energy storage density. It is believed that the electric dipoles formed by the treatment caused defects are responsible for the high dielectric performance observed. The dipoles also result in a pinching effect in the polarization - electric field hysteresis loop. For the composites with 20.0 wt% SiO2, the composites sintered from BT treated at 950 °C exhibit a dielectric constant that is more than 6 times of that of the composites sintered from untreated BT and this high dielectric constant is almost independent of the temperature over a temperature range from −50 to 140 °C.

Effect of 80 MeV O6+ ion irradiation on structural, morphological, dielectric, and ferroelectric properties of (1-x)PVDF/(x)BaTiO3 nanocomposites

The polyvinylidene fluoride/barium titanate (1-x)PVDF/(x)BaTiO3 nanocomposite films (x = 0.2 and 0.5) were prepared by solution mixing method. The dielectric constant (e′) was increased by the BaTiO3 incorporation in the PVDF matrix. The pristine PVDF and nanocomposite films were uniformly irradiated with 80 MeV O6+ ion beam over an area of 1 cm2 at room temperature under the high vacuum of ~ 5 × 10−6 Torr with ion fluences, 5 × 1010, 2 × 1011, and 2 × 1012 ions/cm2. After irradiation, recrystallization and α→β phase transition were observed in PVDF through X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy analysis. However, almost complete amorphization was observed in BaTiO3 filler in (1-x)PVDF/(x)BaTiO3 nanocomposite samples. After irradiation, the dielectric constant (e′) increases at lower fluence (5 × 1010 ions/cm2) while decreases at higher fluence (2 × 1012 ions/cm2) as compared with the pristine samples. The creation of free radicals in PVDF due to chain scission and crosslinking observed upon irradiation is responsible for the observed behavior of dielectric constant (e′). While in nanocomposites, the change in the dielectric properties of BaTiO3 in nanocomposites samples after irradiation can be associated with the radiation-induced amorphization of BaTiO3. After irradiation, both the remanence polarization and coercive field increase for PVDF while decrease for nanocomposite samples. The observation of amorphousity in BaTiO3 phase through swift heavy ion irradiation is interesting and important from a fundamental point of view.

Effect of domain switching contribution on polarization current, leakage current and switching charge density studied by PUND method in (Ba1−x,Cax)TiO3 ceramics

The present study illustrates the effect of domain switching on polarization current and leakage current in (Ba1−xCax)TiO3 (0 ≤ x ≤ 0.4) lead-free ceramics prepared by sol-gel method. The influence of Ca2+ concentration on the structural, microstructure and dielectric properties of BaTiO3 (BT) was investigated. The study shows that domain switching has a significant effect on polarization current and switching leakage current behavior. Un-switching leakage current was observed to be lower than the switching leakage current in whole range of electric field due to restrict the space charges contribution in the absent of domain switching effect. The highest polarization current and lowest leakage current were achieved in the composition x = 0.2. Effect of frequency into polarization current has been introduced, where the current peak increased and shifted to higher electric field by increasing the applied frequency due to the high rate change of electric field corresponding domain switching rate. The difference between remnant polarization estimated by P-E loop and Positive Up Negative Down (PUND) methods has been highlighted. The results show that the remnant polarization appraised by PUND method is lower than the value estimated by P-E loop due to absence of the leakage current contribution.

Effects of Bi2O3 and MgO on microstructure and dielectric properties of BaTiO3–(Na1/4Bi3/4)(Mg1/4Ti3/4)O3 system

Bi2O3- and MgO-doped BaTiO3–(Na1/4Bi3/4)(Mg1/4Ti3/4)O3 (BT–NBMT) ceramics were synthesized from a solid-state approach, and then the impacts of Bi2O3 and MgO dosages on the structures and dielectric characteristics were studied. Obvious dual peaks were observed with Bi2O3 dosage to 0.04 and MgO dosage to 0.02. The low-temperature dielectric stability and grain size of the Bi2O3 dopant were improved, while those of the MgO dopant hardly changed with MgO dosage to 0.02, indicating the core/shell microstructure of BT–NBMT was formed following the dissolving-precipitating mechanism of BT systems doped with low-melting-point substances. The low-temperature dielectric stability of the Bi2O3- or MgO-doped BT–NBMT ceramics first improved and then deteriorated with the increase of doping concentrations. High-temperature stability and diffuse-state transition were found in the optimal ceramics. The second phases of Bi2O3 and MgO, magnesium titanium compounds were observed in Bi2O3 and MgO dopants, respectively. Bi2O3-doped and MgO-doped ceramics exhibited a fine-grained microstructure and significant grain growth, respectively, and the core/shell microstructure was responsible for the dielectric temperature stability for Bi2O3 dopants and collapsed to a homogeneous one with remarkable grain growth and the second phases for MgO dopants.

The defect and dielectric properties of Nb and Mn co-doping BaTiO3 ceramics

abstractThe effect of Nb and Mn as dopants on the dielectric properties of BaTiO3 based ceramics was investigated. When the content of Nb <1.0% mol (Mn =1.6% mol), a diffuse phase transition (DFT) character appeared, and a normal-like ferroelectrics character was observed as the content of Nb is 1.0% mol. When the content of Nb increases up to 1.1% mol, it showed a dielectric relaxation. The binding energy for different defect associations [] and [] calculated using computer simulation techniques and the dielectric properties related to polar nanoregions (PNRs) were discussed.

Microstructure and dielectric properties of BaTiO3–(Bi0.5Na0.5)TiO3–NiNb2O6 ceramics

0.9BaTiO3–0.1(Bi0.5Na0.5)TiO3–x mol% NiNb2O6 (x = 0, 0.5, 1.0, 1.5, 2.0, 2.5) ceramics were prepared through traditional solid-state reaction method. The effects of NiNb2O6 doping on the dielectric properties and the microstructure of ceramics were investigated systematically. The results showed that the grain size of the ceramics decreased with the increase of NiNb2O6 doping amount. Ba11(Ni,Ti)28O66+x and Nb2O5 were detected in the X-ray diffractions patterns. The Curie point Tc increased slightly with the increase of NiNb2O6 doping amount. It was interesting to find that the dielectric constant at low temperature of the ceramics first increased and then decreased with the increase of NiNb2O6 concentration. Dielectric temperature stability of 0.9BaTiO3–0.1(Bi0.5Na0.5)TiO3 ceramics greatly depended on NiNb2O6 content. The optimum dielectric properties meeting the X9R specification were obtained in the composition of 0.9BaTiO3–0.1(Bi0.5Na0.5)TiO3 with 1.5 mol% NiNb2O6 sintered at 1200 °C, er = 1652 and tanδ = 1.8% at room temperature.

Structure and Electrical Characteristics of BaTiO&lt;sub&gt;3&lt;/sub&gt; and Ba&lt;sub&gt;0.99&lt;/sub&gt;Er&lt;sub&gt;0.01&lt;/sub&gt;TiO&lt;sub&gt;3&lt;/sub&gt; Ceramics

Conventional solid state reaction method was used to prepare BaTiO3 and Ba0.99Er0.01TiO3 ceramics. Influence of Er3+ ion incorporation on their structural, microstructural and electrical properties was studied. The phase pure samples were obtained when heated at 1400 °C for overnight. The tetragonal perovskite phase of BaTiO3 and Ba0.99Er0.01TiO3 was confirmed by using X-ray Diffraction (XRD) analysis which is in agreement with results obtained from Rietveld refinement analysis. The lattice parameters and unit cell volume of BaTiO3 increased when doped with Erbium. Microstructural analysis of BaTiO3 and Ba0.99Er0.01TiO3 ceramics showed that the grain sizes of BaTiO3 and Ba0.99Er0.01TiO3 significantly decreased. The dielectric properties of BaTiO3 and Ba0.99Er0.01TiO3 were investigated as a function of temperature and frequency. It revealed that the Curie temperature (TC) increased by doping Er content from 110 °C to 120 °C. Ba0.99Er0.01TiO3 exhibited the high value of dielectric constant (ε=5929) at TC of 120 °C. The capacitance-voltage characteristic revealed that the voltage breakdown for both BaTiO3 and Ba0.99Er0.01TiO3 exceeded 30 V.

Effects of Nb5+ Addition on Microstructure and Dielectric Properties of BaTiO3

Effects of Nb⁵⁺ Addition on Microstructure and Dielectric Properties of BaTiO₃

Effect of Sintering Time on Dielectric Properties of Barium Titanate and Nb Doped Barium Titanate

Barium titanate (BaTiO3) with its perovskite structure is a promising dielectric material for many applications such as transducers, actuators, high-k dielectrics and multilayer ceramic capacitors (MLCC). In this study, we have investigated the effect of sintering time on dielectric properties of BaTiO3 and Nb-doped BaTiO3. BaTiO3 was doped with 0.3 mol % niobium oxide (Nb2O5). At first, nanosized pure BaTiO3 and Nb2O5 doped BaTiO3 were milled, dried and pressed into pellets to prepare green samples. Then, the samples were sintered at 1275°C for different time periods ranging from 2 to 5 hrs. Single stage sintering was adopted for the densification of prepared samples. Microstructure of the sintered samples was investigated employing Field-emission scanning electron microscope (FESEM). Dielectric properties of the samples were measured using an impedance analyzer. Finally, a correlation was established between the dielectric properties of the sintered samples and their microstructure. Nb has shown to provide strong inhibiting effect after sintering the samples in the range of 2 to 5 hours at 1275°C thereby, resulted in higher dielectric properties of doped BaTiO3 ceramics compared to that of pure BaTiO3. The best room temperature dielectric constant of 7200 was obtained for Nb doped BaTiO3 sintered at 1275°C for five hours. Such improved dielectric constant is attributed to the optimum grain size of about 1 micron at this sintering temperature.

Relaxor Behaviors in xBaTiO3-(1-x)CoFe2O4Materials

Dielectric properties of xBaTiO₃–(1-x)CoFe₂O₄ composite materials have been investigated. Dielectric properties of BaTiO₃, CoFe₂O₄ and 0.5BaTiO₃–0.5CoFe₂O₄ samples show frequency dependence, which is classified as relaxor behavior with different relaxing degree. The relaxor behaviors were described using the modified Curier-Weiss and Vogel–Fulcher laws. Among three above samples, the BaTiO₃ sample has highest relaxing degree. Photoluminescence spectral indicated defects, which might in turn control relaxing degree.

Structure, magnetic and dielectric properties of BaTiO3–Co multi-layer nano-composite films

The BTO–Co multi-layer nano-composite films have been deposited successfully, which consist of amorphous BTO layers and Co nano-particles layers. By controlling Co layer thickness from 6.3 to 0.3nm, the resistivity of BTO–Co films increases from 100 to 106μΩm. And the magnetization of films changes from 0.73 to 0.01T. Noteworthy, when the Co layer thickness is 2.5nm, the films show superparamagnetic properties. HRTEM observation clearly shows that these films have the nanometer-sized metal Co particles of around 2nm in diameters and a homogeneous dispersion. With lower Co layer thickness, the BTO–Co films exhibit high electrical resistivity. The dielectric constant tested at 1kHz of these BTO–Co films increases from about 10–40, by controlling the Co layer thickness.

Substitutional behavior and dielectric property of x(Na0.5K0.5)NbO3–(1−x)BaTiO3 using x-ray absorption fine structure spectroscopy

The doping effect of (Na0.5K0.5)NbO3 (NKN) on the dielectric properties of BaTiO3 have been investigated through the local atomic structure analyses. The dielectric constant of a specimen with x=0.05 was about 105% higher than that of pure BaTiO3. Through Ti K-edge x-ray absorption near edge structure (XANES) spectroscopy, it could be determined that the improved dielectric properties are due to the donor substitution by Nb-doping in the B-site. An increase in the XANES intensities with x indicates an increase in degree of hybridization, relating to the donor level, which leads to an increase in conduction electrons. Thus, the enhancement of the dielectric properties is attributed to the increased polarization interaction between the conduction electrons and the relaxation mode. The polarization of the electrons is confirmed by the comparative analysis of bond length data between TiO and NbO, derived from Ti and Nb K-edge extended x-ray absorption fine structure (EXAFS) spectroscopy.

Effects of Nb2O5 addition on the microstructure and dielectric properties of BaTiO3–Bi0.5Na0.5TiO3 ceramics

The influence of Nb2O5 on the microstructure and dielectric properties, including temperature dependence of permittivity, dielectric loss, and Curie temperature, has been investigated on BaTiO3–Bi0.5Na0.5TiO3 (abbreviated as BBT) ceramics. Experiments reveal that incorporation of a proper content of Nb2O5 in BBT ceramics can control the grain growth, reduce the dielectric loss, shift the Curie temperature to higher temperatures and significantly improve temperature characteristics of the BaTiO3–Bi0.5Na0.5TiO3 ceramics. As a result, a novel X10R material is developed in the system, which is very promising for practical use in X10R multilayer ceramic capacitors. With the addition of 2.0 wt% Nb2O5, the ceramics sintered at 1,150 °C showed favorable dielectric properties at 25 °C (er = 1,730, tanδ = 1.39 × 10−2, and TCC = 12.0 %).

Effect of a BaO-CuO-Bi2O3-B2O3 glass flux, and its processing on the dielectric properties of BaTiO3

A series of BaTiO3 along with various flux oxides has been sintered step-wisely to yield a low sintering temperature flux glass composition. The developed glass flux (Ba-Cu-Bi-B system) was added to BaTiO3 with different amount, and eventually yielded a low sintering temperature of BaTiO3 at 900°C with 7wt% flux glass addition. To investigate the influence of processing methods, a flux glass shell-BaTiO3 core structure was developed by using separate ball milling schedule of glass and barium titanate powders. Comparison of resultant dielectric properties was made among different processing methods, and this flux shell processing methods notably modifies the dielectric properties of sintered samples comparing to conventional processing methods. The subsequent structural information, morphology, and phase stability of sintered samples were investigated by Infrared spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and X-ray diffraction (XRD) respectively. 93wt% BaTiO3-7wt% glass with the flux shell structure displayed an inhibited cubic phase grain growth, and a reduced tetragonality associated with Cu doping was confirmed by X-ray diffraction. A high dielectric constant (>3000) as well as a low lossy factor (<0.03) of this particular series of sample was reported. X-ray photoelectron spectroscopy showed that bridging oxygen species decreases with increasing Nd addition, indicating that the Nd bonds to the glass network as a network modifier instead of being doped into BaTiO3 lattice through the flux shell. Thus, we concluded that the glass flux shell plays the role of sintering additive, Cu doping ion (contained in glass) carrier, and Nd alien dopant block.

Dielectric properties of BaTiO3 by molecular dynamics simulations using a shell model

We calculated the susceptibilities of BaTiO3 by molecular dynamics (MD) simulations using an isotropic shell model of Tinte et al. (S. Tinte, M.G. Stachiotti, S.R. Phillpot, M. Sepliarsky, D. Wolf, and R.L. Migoni, Ferroelectric properties of BaxSr1-xTiO3 solid solutions obtained by molecular dynamics simulation. J Phys Condens Matter, 16, pp. 3495–3506, 2004). The anisotropy of the susceptibilities was reproduced for the ferroelectric phases. However, the susceptibilities were significantly underestimated with respect to experimental ones especially for the a direction. The densities of probabilities of the local polarisations in this model for both the macroscopically polarised and not polarised directions were strongly localised around their average values, leading to the small fluctuation of the total dipole moment of the MD cell and resulting in the underestimated susceptibilities. The order–disorder character was found to be stronger in this model than in the effective Hamiltonian based on the first principles calculations.