Dielectric Properties Of BaTiO Research Articles

Facile preparation and dielectric properties of BaTiO3 with different particle sizes and morphologies.

BaTiO3 nanoparticles were prepared by the hydrothermal method, and the effect of 1-(propyl-3-methoxysilyl)-3-methylimidazole chloride on the size of BaTiO3 particles was investigated. The obtained BaTiO3 was characterized by XRD, SEM, TEM, and Raman spectroscopy; and the dielectric properties of BaTiO3 ceramic sheets were tested. The results indicate that the spherical BaTiO3-N prepared without an ionic liquid was in a tetragonal phase with an average particle size of 129 nm. When an ionic liquid was added, the size of the BaTiO3-IL decreased and the degree of agglomeration increased. In addition, with increasing quantity of ionic liquid, the tetragonal-phase content of BaTiO3-IL gradually decreased until complete transformation into cubic phase. The dielectric constant of the BaTiO3-N ceramics was the highest, and the dielectric constant decreased with decreasing BaTiO3 particle size. Moreover, two types of BaTiO3 nanoparticles (bowl- and sea urchin-shaped) were prepared by changing the hydrothermal conditions and additives. The average particle size of the former was 92 nm, the tetragonal-phase content was ca. 90%, and the dielectric constant was large; whereas the sea urchin-shaped BaTiO3 consisted of small particles in the cubic phase, and the dielectric constant was small.

Study of structural and dielectric properties of Nickel-doped BaTiO3 material

<p><span lang="EN-US">In this work, the effect of nickel (Ni) insertion on the structural and dielectric properties of BaTiO<sub>3</sub> material was investigated. A series of powders of composition <span>Ba<sub>1-x</sub>Ni<sub>x</sub>TiO<sub>3</sub> </span>(x = 0, 0.05, 0.1, 0.15 and 0.20) were synthesized by solid method. The analysis by X-Ray Diffraction (XRD) shows that the obtained compounds crystallize in a phase of perovskite type. All the peaks are indexed in a phase of quadratic symmetry. Characterization by the Scanning Electron Microscope (SEM) indicates a heterogeneous microstructure of the grains. <span>The study by spectroscopy of impedance in</span> the frequency range [500Hz-1MHz] <span>highlighted the effect of the nickel insertion on </span>the transition temperature and the dielectric constant value.</span></p>

Influence of ZrO_2 Addition on the Structure and Dielectric Properties of BaTiO_3 Ceramics

6th International Congress and Exhibition on Advances in Applied Physics and Materials Science (APMAS) -- JUN 01-03, 2016 -- Istanbul, TURKEY

Effect of mechanical milling on the structural and dielectric properties of BaTiO 3 powders

Barium titanate (BaTiO3) is a well-known ferroelectric material and widely used in electronic industries for the multi-layer ceramic capacitor. In this reported work, commercially available tetragonal BaTiO3 (BT) powders were taken to study the size effect on the structural and dielectric properties of the BT ceramics during high-energy ball milling (0–110 h). The same perovskite when kept under a normal atmospheric condition after milling shows gradual increase of additional crystalline phase that occurred because of the absorption of atmospheric CO2 gas, which is characterised as orthorhombic BaCO3. The milled BT samples were characterised by X-ray diffraction and small-angle X-ray scattering and a dielectric analyser. The purpose of this work was to study how the dielectric property of nanoBT ceramics varies with reduction of particle size, structural changes and the absorption of carbon by these nanopowders. It was observed that the dielectric constant of the BT powders increases with particle size reduction during milling. The dielectric behaviour of the BT ceramics significantly changes with polymorphic phase transformation in nanocrystalline BT at different stages of milling. The capacitance of nanoBT powders is significantly changed with the absorption of carbon by the nanoBT powders in a humid atmosphere.

Effect of a Boron Additive on the Microstructure and Dielectric Properties of BaTiO<sub>3</sub> Thin Films Formed by Nanocrystal Deposition

Highly crystallized BaTiO3 thin films were fabricated by a nanocrystal sintering process. Boron alkoxide was introduced into a slurry of Mn-doped BaTiO3 nanocrystals with particle sizes of 5-7 nm. The deposited nanocrystal film on a (111)-oriented Pt/TiO2/Al2O3 substrate was sintered at a low temperature of 800 °C and the obtained film had highly densified and oriented microstructures. We found that the boron additive enhanced the grain growth of nanoparticles and as a result the dielectric constant of the thin film increased to 1100 at 10 kHz, which is much higher than that of undoped BaTiO3 thin films.

Influence of Oxygen Substoichiometry on the Dielectric Properties of BaTiO3‐δ Nanoceramics Obtained by Spark Plasma Sintering

Oxygen‐deficient BaTiO3‐δ nanoceramics were prepared by spark plasma sintering. Partially reduced raw nanopowders led to unusual dielectric properties. A short postsintering treatment was performed to reach a high εr/tan δ, which makes them attractive for industrial applications such as low‐frequency capacitors. Surprisingly, our ceramics also remained black even after annealing for 5 days at 850°C in air, indicating the presence of barriers against oxygen diffusion. This exceptional behavior in pure barium titanate was consistent with a core–shell structure made of semiconductive grains and insulating grain boundaries, due to the presence of Ti3+/Ti4+ and oxygen vacancies.

Effect of particle size on the densification and dielectric properties of BaTiO3 ceramics prepared by liquid phase sintering

AbstractUsing starting BaTiO3 powders of various particle sizes, we investigated the densification and dielectric characteristics of BaTiO3 ceramics sintered at low temperature with the addition of ZnO‐B2O3‐SiO2 (ZBS) glass as sintering aids. Scanning electron microscopy, X‐ray diffraction, Raman spectroscopy, and LCR meter were used to examine the structure and dielectric properties. The results indicated that the particle size of raw powders had a dramatic influence on the densification and dielectric properties of BaTiO3 ceramics. The grain size of the final ceramics was almost proportional to the particle size of the starting BaTiO3 powder. Moreover, the tetragonality (c/a ratio) and Curie temperature is increased with the increase of grain size of the BaTiO3 ceramics. The relative density of 96% and the dielectric constant of 1440 were obtained for the BaTiO3 ceramics prepared with the raw powders of average particle size of 800 nm. In addition, the sintering temperature was reduced to 1100 °C due to the addition of 5 wt% ZBS glass.

Effect of Cerium Doping on Microstructure and Dielectric Properties of BaTiO 3 Ceramics

A solid state reaction method was used to synthesize barium titanate (BT) and barium cerium titanate (BCT) ceramics at sintering temperature of 1473 K for 4 h. The effect of cerium (Ce) on the structure, microstructure and dielectric properties of BCT was investigated. The scanning electron microscopy (SEM) investigations revealed that the grain size increases with increasing Ce content. The X-ray diffraction (XRD) patterns showed mostly the BT phase, where the lattice parameter decreased with the addition of Ce. The temperature dependence of dielectric constant showed decrease in the phase transition temperature with higher Ce content. The dielectric constant decreased slightly with increasing frequency. The direct current (dc) density-voltage characteristics of the ceramics showed ohmic behavior for both the BT and BCT. As the temperature increased, the dc resistivity of the ceramics decreased. The activation energy increased with increasing Ce content.

Effects of Kaolinite addition on the densification and dielectric properties of BaTiO 3 ceramics

Commercial Kaolinite was employed as sintering aid to reduce the sintering temperature of BaTiO 3 ceramics. The effects of Kaolinite content and sintering temperature on the densification, microstructure and dielectric properties of BaTiO 3 ceramics have been investigated. The density characterization results show that the addition of Kaolinite significantly lowered the sintering temperature of BaTiO 3 ceramics to about 1200 °C. XRD results show BaTiO 3 ceramics with a low amount of Kaolinite exhibited perovskite structure, but 10.0 wt% Kaolinite additions resulted in the formation of a secondary phase, BaAl 2Si 2O 8. BaO–TiO 2–Al 2O 3–SiO 2 glass phase was formed and improved the average breakdown strength of ceramics, which was supported by SEM-EDX results. The Kaolinite content had shown a strong influence on the dielectric constant and the diffuse transition. BaTiO 3 ceramic with 4.0 wt% Kaolinite addition possessed well temperature stability of dielectric constant.

The dielectric properties of BaTiO 3 based ceramics co-doped with Bi/Mn

BaTiO 3 based ceramics (with some additives such as ZrO 2, SnO 2, etc.) were prepared by solid state reaction. Mn 2+ or Mn 3+ as an acceptor substituting for Ti 4+ in B site and Bi 3+ as a donor substituting for Ba 2+ in A site were co-doped in BaTiO 3 based ceramics. The dielectric properties of BaTiO 3 based ceramics co-doped with Bi/Mn were investigated. The results show that the dielectric properties of BaTiO 3 based ceramics co-doped with Bi/Mn are affected by the mole ratio of donor and acceptor (Bi/Mn). When the mole ratio of donor and acceptor is high, dielectric dispersion behavior was observed and the dielectric constant decrease and remnant polarization, coercive field and piezoelectric constant will varied. When Bi varied from 1.0% to 2.0 mol% (Mn = 0.8 mol%), remnant polarization from 10.35 to 2.25 μC/cm 2, coercive field from 4 to 2.75 kV/cm, and piezoelectric constant d 33 from 137 to 36 pC/N respectively.

Effect of Na 0.5Bi 0.5TiO 3 on dielectric properties of BaTiO 3 based ceramics

In this work, Na 0.5Bi 0.5TiO 3 (NBT) was used to improve the high temperature dielectric properties of Nb, Co-doped BaTiO 3 (BT). Different x was selected ( x = 0, 0.02, 0.04, 0.06, 0.08, 0.1, 0.2, 0.3, 0.4) to optimize the ratio of BT to NBT in (1 − x) BT– xNBT solid solution. The dielectric constant of the original X7R material is about 4900 at room temperature, decreasing to 2500 with NBT addition ( x = 0.2). Of important is that the temperature stability was improved with dielectric constant variation being less than ±15% up to 160 °C.

Effect of Cu Content on Dielectric Properties of BaTiO<SUB>3</SUB>/Cu Composite Ceramics

用传统固相法制备了(1- x )BaTiO 3 / x Cu( x =5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%,30 wt%)复相陶瓷, 研究了Cu含量对复相陶瓷材料的显微结构、渗流阈值及介电性能的影响. 研究结果表明BaTiO 3 /Cu复相陶瓷材料的电阻率随着铜含量的增加而下降, 且在渗流阈值( x =25wt%)附近呈现非线性的下降趋势, 复合材料从绝缘体逐渐变为导体. 室温下1 kHz当Cu含量达到 x =30wt%时复相陶瓷的介电常数为~9000, 这是由于在导体和绝缘体的相界面处积累大量的空间电荷, 并由此产生界面极化, 导致介电常数的显著增大, 且随着导体含量的增加, 这种界面效应更加明显. 复相陶瓷的介电损耗随着铜含量的增加而增大, 但随着频率的升高, 由于空间电荷的减少又会使损耗呈现下降的趋势. 在25~115℃的温度范围内, 复相陶瓷温度系数小于5%,具有很高的介电常数温度稳定性.

Core-shell structure and size effect in barium titanate nanoparticle

A quantitative core-shell structure model on the grain size effect of nano-BaTiO 3 ceramics has been proposed on the basis of the Ginsburg–Landau–Devonshire thermodynamic theory. In this study, we have considered the existence of surface effects, which leads to the core-shell structure in BaTiO 3 nanoparticles consisting of inner tetragonal core, gradient lattice strain layer, and surface cubic layer. The size effects on the spontaneous polarization, Curie temperature, c/ a ratio, and electrocaloric and dielectric properties of BaTiO 3 ferroelectric nanoparticle are successfully explained. Theoretical and experimental results for BaTiO 3 nanoparticle are compared and discussed.

How grain boundaries modify the high-temperature dielectric response of ferroelectric electroceramics like BaTiO 3?

Dielectric properties of BaTiO 3 ferroelectric ceramics were studied over wide frequency and temperature ranges. The materials showed complex dielectric behaviors, which included an anomalous increase of permittivity towards higher temperatures. Important, this property tended however to saturate to values that varied with grain-boundary density. Application of impedance spectroscopy and consideration of the series-layer model allowed a coherent discussion of these and other interesting observations from this work. In particular, analysis of the relationship existing in this model between macroscopic and microscopic dielectric properties rendered possible to account for grain vs. grain-boundary dielectric behaviors, in harmony with microstructure features, and to know the dielectric anomaly strength to be in fact expected from grain boundaries in such polycrystalline materials.

Dielectric Properties of BaTiO$_3$-ceramic Prepared by Freeze Drying Method

Dielectric Properties of BaTiO$_3$-ceramic Prepared by Freeze Drying Method

Effects of impurities on the properties of BaTiO 3 synthesized from barium titanyl oxalate

The effects of impurities, such as H +/Cl − and Zr 4+, on the tetragonality (= c/ a) of BaTiO 3 were examined to determine their effect on the synthesis of nano-sized particles with a high dielectric constant. The quantity of incorporated impurities was adjusted by controlling the milling and washing processes, which are essential for the preparation of BaTiO 3 using an oxalate method. The tetragonality decreased with increasing impurity concentration, which can be actual proof of the assumption that impurities decrease the tetragonality due to the enhanced internal strain fields. Moreover, the experimental results showing a tetragonality of 1.0068 for a particle size of 119 nm suggest that the dielectric properties of BaTiO 3 prepared by the oxalate route may be comparable with those prepared by solid-state reactions by optimizing the process parameters.

Effects of multi-doping of rare-earth oxides on the microstructure and dielectric properties of BaTiO 3

Effects of multi-doping of rare-earth oxides (R = Yb, Sm, Ho, La and Nd) on the microstructure development and electric properties of BaTiO 3 ceramics were studied. The addition of samarium oxide leads to poor densification and small grains, whereas ytterbium oxide develops large grains and secondary phases along the grain boundary, and Ho ion with an intermediate ionic radius gives rise to higher densities with fine grains. The grain size of Yb-doped BaTiO 3 decreased with increasing Sm contents. The system coated with 2.0 at.% Sm and 2.0 at.% Yb exhibited dense microstructures with uniform small grains, and Yb-rich second phases were not observed. It was confirmed that an appropriate ratio of donor to acceptor is necessary to the optimum microstructure. Curie temperature of rare-earth doped BaTiO 3 was strongly dependent on the unit-cell volume associated with the ionic sizes of rare-earth ions.

Effect of domain wall on the dielectric properties of the BaTiO 3/SrTiO 3 superlattices

Based on a phenomenological thermodynamical theory, the effect of the domain wall on the dielectric properties of the polydomain BaTiO 3/SrTiO 3 superlattices with 180° electric domains in the BaTiO 3 layer is investigated. Theoretical analysis indicates that complete polarization suppression and the largest dielectric response take place at approximately 72% and 53% of the critical volume fraction of the SrTiO 3 layer for the domain wall energy parameter A=3×10 7 and 5×10 7, respectively. The dielectric properties largely depend on both the volume fraction of the SrTiO 3 layer and the domain wall energy parameter. Moreover, the gigantic dielectric response which occurs in single-domain BaTiO 3/SrTiO 3 superlattices cannot appear due to the 180° polydomain state in the BaTiO 3 layer, which is in agreement with the previous prediction. The high domain wall energy parameter results in the stabilization of the paraelectric state in the BaTiO 3 layer, however, the enhancement of the domain wall energy parameter within a certain scale increases the dielectric properties greatly.

Surface modification of BaTiO 3 particles by silane coupling agents in different solvents and their effect on dielectric properties of BaTiO 3/epoxy composites

The surface of BaTiO 3 particles was modified by 3-glycidoxypropyltrimethoxysilane (GPTMS) to attach epoxy groups on them and to improve their compatibility with epoxy resin. First, in order to analyze the effect of solvents on the degree of surface modification of BaTiO 3 particles, the surfaces of BaTiO 3 particles were modified with GPTMS in water, ethanol, and xylene at 80 °C. FT- nIR analysis showed that due to the ring-opening reaction, the epoxy group on BaTiO 3 particles was reduced after surface modification in ethanol and disappeared after surface modification in water. In contrast, when BaTiO 3 particles were modified in xylene, the epoxy groups remained. Then, the relationships among these surface structure differences, viscosity of BaTiO 3/epoxy/N-methyl-2-pyrrolidinon (NMP) suspensions, the surface morphologies of BaTiO 3/epoxy composites, and the dielectric properties of BaTiO 3/epoxy composites were investigated. While there was no relationship between the suspension viscosity and the dielectric properties of BaTiO 3/epoxy composites, a BaTiO 3/epoxy composite with a smooth surface and high dielectric properties was obtained when the BaTiO 3 surface was modified in xylene and the epoxy groups were effectively retained on the surface.

Phase transition and dielectric properties of BaTiO 3 ceramics containing 10 mol% BaGeO 3

Dielectric properties and the cubic ⇆ tetragonal phase transition temperature of dense BaTiO 3 ceramics containing 10 mol% BaGeO 3, sintered between 840 and 1350 °C, have been investigated. The ceramic bodies were prepared from a nano-sized BaTi 0.9/Ge 0.1O 3 powder consisting of both BaTiO 3 and BaGeO 3 phases. The addition of BaGeO 3 leads to a reduction and broadening of the permittivity maximum, and to a small downshift of the paraelectric ⇆ ferroelectric phase transition temperature, compared to a pure BaTiO 3 ceramic. Lower sintering temperatures and thus small grain sizes of the ceramics cause an additional reduction of the maximum permittivity down to 2800. Both DTA and dilatometric measurements reveal also a downshifting of the phase transition temperature, as well as a decrease of the latent heat.