BaTiO3 Particles Research Articles

The influence of mechanical activation on the morphological changes of Fe/BaTiO3 powder

Crystal structure and morphology of mechanically activated nanocrystalline Fe/BaTiO3 was investigated using a combination of spectroscopic and microscopic methods. These show that mechanical activation led to the creation of new surfaces and the comminution of the initial powder particles. Prolonged milling resulted in formation of larger agglomerates of BaTiO3 and bimodal particle size distribution, where BaTiO3 particles were significantly larger than those of iron-containing phases. Milling times of 210min and above lead to a significant decrease in temperature of the oxidation of iron in the sample, indicating abrupt change in reactivity. Raman spectroscopy analysis has revealed that activation had a pronounced influence on Fe/BaTiO3 lattice, thereby affecting both the stability of the crystal structure and the phase transition phenomena.

A novel double-coating approach to prepare fine-grained BaTiO3@La2O3@SiO2 dielectric ceramics for energy storage application

We prepared submicron BaTiO3@La2O3@SiO2 particles with high uniformity and dispersity using a novel double-coating method. The monodispersed submicron BaTiO3 particles (diameter about 240 nm) formed a ferroelectric core that was coated with La2O3 and SiO2 as a modified layer and a layer with high electrical resistance, respectively, and the thickness of two shells was about 20 nm. We then obtained dense, fine-grained BaTiO3-based energy storage ceramics (grain size ≤ 300 nm) with the same particle structure by means of sintering in air at 1240 °C for 2 h. As the amount of SiO2 increased, the content of the tetragonal phase and the densification first increased and then decreased. When the amount of SiO2 exceeded 9.0 wt%, a secondary phase with Ba2TiSi2O8 appeared, and the core-shell structure disappeared. The BaTiO3@La2O3@SiO2 ceramics met the X8R requirements, with a maximum dielectric constant of 3362 at 6.0 wt% SiO2, and a low dielectric loss at room temperature (< 0.020, with a minimum of 0.011). The remnant polarization deceased from 13.80 to 1.21 μC/cm2, while the energy storage density first increased and then decreased as the amount of SiO2 coating increased from 0.0 to 12.0 wt%. The discharged energy storage density was highest (0.54 J/cm3) for samples containing 9.0 wt% SiO2 under a maximum polarization field of 13.6 kV/mm, and the energy storage efficiency of the ceramic was >85%.

Formation and Accumulation of Intragranular Pores in the Hydrothermally Synthesized Barium Titanate Nanoparticles

As highly integrated circuits are demanded for high‐performance electric devices, small sizes of barium titanate (BaTiO3) as a dielectric material are desirable for the application of multilayer ceramic capacitors. Since the small sizes of the particles degrade the dielectric property, especially below a certain critical size, understanding the probable cause is significant for the high‐performance capacitors. Here, we have demonstrated nanosized BaTiO3 with average size below 30 nm and a uniform size distribution. High‐resolution transmission electron microscopy (TEM) shows that the as‐synthesized BaTiO3 contains intragranular pores. We have analyzed the correlation between the intragranular pores inside nanoparticles and their phase ratio of cubic and tetragonal. We have found that the presence of the intragranular pores affects low tetragonality of BaTiO3 particles, and the intragranular pores are generated by the accumulation of hydroxyl groups during hydrothermal reaction. Formation and accumulation of intragranular pores have been investigated by ex‐situ synchrotron X‐ray diffraction and TEM analysis, suggesting the phase evolution model of nanosized BaTiO3.

Microstructure and properties evolution for textured PbMg1/3Nb2/3O3-PbTiO3 ceramics

Plate-like BaTiO3 (BT) particles were synthesized by the topochemical reaction method and BT textured PMNT ceramics were sintered from 1000°C to 1200°C. The microstructure and properties evolution were investigated in detail. Highly textured PMNT ceramics were obtained by sintering at temperature above 1150°C, and the microstructure also changed from small equiaxed grains to large cubic grains. Ferroelectric and piezoelectric properties improved with increase of sintering temperature. Textured PMNT ceramics sintered at 1150°C exhibit the largest electric field induced strain which was 2 times larger than that of untextured ceramics due to high degree of orientation and relative high density.

Enhanced piezoelectricity in plastically deformed nearly amorphous Bi12TiO20-BaTiO3 nanocomposites

Bulk Bi12TiO20-BaTiO3 (BTO-BT) nanocomposites are fabricated through the high-temperature interfacial reaction between nanometer-sized BaTiO3 particles and melting Bi12TiO20. Although the obtained BTO-BT nanocomposites are nearly amorphous and display very weak ferroelectricity, they exhibit relatively strong piezoelectricity without undergoing the electrical poling process. The volume fraction of crystalline Bi12TiO20 is reduced to less than 10%, and the piezoelectric constant d33 is enhanced to 13 pC/N. Only the presence of the macroscopic polar amorphous phases can explain this unusual thermal stable piezoelectricity. Combining the results from X-ray diffraction, Raman spectroscopy, and thermal annealing, it can be confirmed that the formation of macroscopic polar amorphous phases is closely related to the inhomogeneous plastic deformation of the amorphous Bi12TiO20 during the sintering process. These results highlight the key role of plastically deformed amorphous Bi12TiO20 in the Bi12TiO20-based polar composites, and the temperature gradient driven coupling between the plastic strain gradient and polarization in amorphous phases is the main poling mechanism for this special type of bulk polar material.

Roll to Roll Electric Field "Z" Alignment of Nanoparticles from Polymer Solutions for Manufacturing Multifunctional Capacitor Films.

A roll to roll continuous processing method is developed for vertical alignment ("Z" alignment) of barium titanate (BaTiO3) nanoparticle columns in polystyrene (PS)/toluene solutions. This is accomplished by applying an electric field to a two-layer solution film cast on a carrier: one is the top sacrificial layer contacting the electrode and the second is the polymer solution dispersed with BaTiO3 particles. Flexible Teflon coated mesh is utilized as the top electrode that allows the evaporation of solvent through the openings. The kinetics of particle alignment and chain buckling is studied by the custom-built instrument measuring the real time optical light transmission during electric field application and drying steps. The nanoparticles dispersed in the composite bottom layer form chains due to dipole-dipole interaction under an applied electric field. In relatively weak electric fields, the particle chain axis tilts away from electric field direction due to bending caused by the shrinkage of the film during drying. The use of strong electric fields leads to maintenance of alignment of particle chains parallel to the electric field direction overcoming the compression effect. At the end of the process, the surface features of the top porous electrodes are imprinted at the top of the top sacrificial layer. By removing this layer a smooth surface film is obtained. The nanocomposite films with "Z" direction alignment of BaTiO3 particles show substantially increased dielectric permittivity in the thickness direction for enhancing the performance of capacitors.

Analog switching in the nanocolloids of ferroelectric liquid crystals

Nanoparticle (NP) dispersion in liquid crystals (LCs) results in significant changes in the physical properties of the existing LC mixtures. Two ferroelectric liquid crystals (FLCs), 5F6T and 6F6T, have been studied for analog switching. The 5F6T sample is doped with titanium dioxide (TiO2) NPs of two different concentrations of the same average particle size and another FLC 6F6T is systematically doped with barium titanate (BaTiO3) NPs of two different average particle sizes at the same concentration. The frequency and temperature dependence of the coercive voltage of FLC nanocolloids has been studied. The V-shaped switching was observed in the case of nano-doped FLCs. The value of inversion frequency for the 5F6T+1.0 wt.% TiO2 doped sample is 30 Hz while it is 24 Hz for the 6F6T+0.5 wt.% BaTiO3 (particle size 5–10 nm) doped sample. The conductivity measurements show that the conductivity of doped samples is higher than the conductivity of their parental FLCs and can be considered the main reason for the V-shaped switching in the FLC nanocolloids, which was initially absent in their parental FLCs.

Microwave heating behavior and microwave absorption properties of barium titanate at high temperatures

The temperature dependence of the microwave absorption behavior of BaTiO3 particles was investigated over various frequencies and temperatures of 25-1000 ∘C. First, using both the coaxial transmission line method and the cavity perturbation method by a network analyzer, the real and imaginary parts of the relative permittivity of BaTiO3 (εr′ and εr″, respectively) were measured, in order to improve the reliability of the data obtained at 2.45 GHz. The imaginary parts of the relative permittivity as measured by the two methods were explored by their heating behaviors. Furthermore, the temperature dependence of the microwave absorption behavior of BaTiO3 particles was investigated for frequencies of 2.0-13.5 GHz and temperatures of 25-1000 ∘C using the coaxial transmission line method.

First principles insights into improved catalytic performance of BaTiO3- graphene nanocomposites in conjugation with experimental investigations

The present work aims to provide first principles insights into the catalytic performance of composites based on BaTiO3 particles decorated over reduced graphene oxide (rGO). Examination regarding the orbital contributions of valence states, conduction states, interaction surface and anchoring of perovskite over rGO have been carried out. Theoretical results thus obtained have been validated using experimental investigation. Further experiments have also been conducted to analyze the catalytic performance of composites with respect to multiple advanced oxidation processes. Charge separation has been improved due to rGO acting as macromolecular photosensitizer. Degradation of xanthene dye (Rhodamine B) and methyl orange (MO) assisted in evaluation of the catalytic performance. Acoustic irradiation provides an additional route to improve degradation by ameliorating catalytic activity (from 0.036min to 0.099min in RhB especially). Synergistic effect obtained through conjugated benefits of oxidation processes with proposed composite, played a crucial role in improving the overall efficiency. The cumulative outcome of the results indicates superior performance of BaTiO3-rGO composites for green and sustainable water treatment applications.

Preparation of BaTiO3/Cu2O and BaTiO3/Cu2O/Au Complexes: Their Photocatalytic and Antipathogenic Effect.

BaTiO3/Cu2O and BaTiO3/Cu2O/Au complexes were prepared from CuCl2, HAuCl4 solution, and BaTiO3 by the solution method. BaTiO3 particles were dispersed in a CuCl2 solution, and the BaTiO3/CuO complex was produced through crystallization of CuO onto the BaTiO3 surface by hydrolysis of CuCl2 in the first stage. After the reaction, CuO was reduced to Cu2O by treatment with glucose, thereby yielding the BaTiO3/Cu2O complex. The BaTiO3/Cu2O/Au complex was prepared by treating the BaTiO3/Cu2O particles with HAuCl4. Under visible light, the obtained BaTiO3/Cu2O0/Au complex showed higher photocatalytic activity than the Degussa P-25sample. In addition, the BaTiO3/Cu2O complex showed excellent antipathogenic effect.

Material Integration for Flexible Electronics for Energy Application Using Nanoparticulated Dense and Stress-Free Ceramic Thick Film

Material Integration for Flexible Electronics for Energy Application Using Nanoparticulated Dense and Stress-Free Ceramic Thick Film

Sintering and Microstructure of BaTiO3 Nano Particles Synthesized by Molten Salt Method.

In order to establish thinner dielectric layers in thick film electronic components such as MLCC (Multilayer ceramic capacitor), BaTiO3 nanoparticles have been utilized. However, studies on the synthesis of nanoparticles smaller than 20 nm, the characteristics of the BaTiO3 powder, and the powder's sintering are lacking. Therefore, this paper aims to synthesize BaTiO3 particles smaller than 20 nm by using the molten salt method and evaluate the microstructure and dielectric properties by varying the sintering temperature from 750 degrees C to 1200 degrees C. Through the molten salt method and by using KOH-KCl mixed salt, 20 nm BaTiO3 powder was synthesized at a low temperature of 150 degrees C. Sintering the pellets formed from the synthesized 20 nm BaTiO3 nano powder led to the observation of an unusual phenomenon where the particles grew to approximate sizes below 850 degrees C where densification progressed. At sintering temperatures above 950 degrees C, particles that expanded into rod shapes were observed and these particles were identified to be unreacted TiO2 based on the results of the EDX (Energy Dispersive X-ray Spectroscopy) analysis and phase analysis results.

Effect of silicone coupling agent on dielectric properties of barium titanate/silicone elastomer composites

BaTiO3 is a type of ceramic with a high dielectric constant, while silicone is a type of elastomer with low elastic modules. Composites made by blending these two materials together can obtain both of their advantages, which has many possible applications in the area of actuators or mechanical sensors. In this study, to improve the dispersity of the BaTiO3 particles, a novel silicone coupling agent was used to modify the surface of the particles. TG and FTIR results showed that the coupling agent was successfully coated on the surface. Raw BaTiO3 and BaTiO3 modified by the silicone coupling agent were incorporated into the silicone elastomer to fabricate the BaTiO3/silicone membranes. Particle size distribution measurements and SEM observations showed that the BT particles can obtain a higher compatibility with the silicone, and both the dispersity of the BaTiO3 particles and the dielectric properties of the BaTiO3/silicone membranes were improved after the surface modification, even without a poling process during the fabrication or measurement. The measuring circuit containing the BaTiO3/silicone membrane is expected to have several applications such as mechanical sensors.

Formation of local electric fields in the ferroelectric BaTiO3 particles-liquid crystal colloids

ABSTRACTInfluence of ferroelectric BaTiO3 particles on dielectric and electro-optic properties of liquid crystals (LC) 5CB and H37 has been investigated. It has been shown that the presence of particles decreases the clearing temperature, increases dielectric permittivity and losses, changes the Freedericksz transition voltage and switching times. A rise time of the BaTiO3-5CB colloid improved while a decay time worsened in comparison with the pure 5CB at all applied voltages. The inverse trends were observed for the H37 matrix.Experimental results are explained by appearance of local electric fields near the polarized ferroelectric particles at application of external electric field.

Reinforced properties of ethylene–propylene–diene monomer composites by vinyltrimethoxysiloxane functionalised barium titanate

In this study, non-conductive ethylene–propylene–diene monomer (EPDM)/barium titanate (BaTiO3) composites with high dielectric constant and low dielectric loss are prepared. Fourier transform infrared (FT-IR) spectra show the chemical adherence of vinyltrimethoxysiloxane oligomer (SG-Si6490) to the surface of BaTiO3 particles. Functionalised BaTiO3 particles have better compatibility with EPDM matrix and promote the cure properties of EPDM composites. It is found that when the content of BaTiO3 increases to 40 vol.-%, the resistivity, rheological, dielectric and mechanical properties of EPDM/BaTiO3 composites change drastically. The dielectric constant of EPDM with 50 vol.-% BaTiO3 at 10 MHz is 15, which is 7.5 times higher than that of EPDM control. Meanwhile, the volume resistivity results show EPDM with 50 vol.-% BaTiO3 is still non-conductive. As for mechanical properties, the tensile and tear strength of EPDM control increase from 1.45 MPa and 8.73 kN m−1 to 10.02 MPa (about seven times higher) and 24.65 kN m−1 (about three times higher), respectively.

Improved photon to current conversion in nanostructured TiO2 dye-sensitized solar cells by incorporating cubic BaTiO3 particles deliting incident

Different structures of dye-sensitized solar cells (DSCs) were fabricated with various compositions and arrangement modes of the photoanodes. The solvothermally grown TiO2 nanoparticles and sol–gel derived spherical TiO2 and BaTiO3 particles were employed as the active and scattering layers of DSCs. TiO2 nanoparticles and spherical particles had pure anatase structure with particle size of 15–30nm and 200–400nm, respectively, whereas 300–800nm BaTiO3 particles showed cubic perovskite structure. The efficiency improvement of mono-layer cells made of TiO2 nanoparticles (i.e., 7.22%) was achieved by light harvesting mechanism. Further enhancement of photovoltaic performance was achieved by light scattering mechanism using two different approaches (e.g., in forms of mono- and double-layer structures). For the mono-layer cells, composed of a mixture of TiO2 nanoparticles and BaTiO3, the highest efficiency of 8.63% was achieved for BaTiO3:TiO2=20:80. The double-layer cell containing the active layer composed of nanoparticles and a mixture of spherical TiO2 and BaTiO3 particles as the scattering layer showed the highest efficiency of 8.81%. Such enhancements were attributed to higher incident photon to current conversion yield due to greater fraction of light scattering, high refractive index of BaTiO3 particles, as well as less recombination of photo-generated electrons.

Highly efficient visible light mediated azo dye degradation through barium titanate decorated reduced graphene oxide sheets

This study investigates BaTiO3 decorated reduced graphene oxide sheets as a potential visible light active catalyst for dye degradation (Rhodamine B). The composites were prepared through conventional hydrothermal synthesis technique using hydrazine as a reducing agent. A number of techniques have been employed to affirm the morphology, composition and photocatalytic properties of the composites; these include UV-visible spectrophotoscopy that assisted in quantifying the concentration difference of Rhodamine B. The phase homogeneity of the composites was examined through x-ray powder diffraction (XRD) and high resolution transmission electron microscopy (HRTEM) was employed to confirm the orientation of the BaTiO3 particles over the reduced graphene oxide sheets. Photoluminescence (PL) emission spectra assisted in determining the surface structure and excited state of the catalyst. Fourier transformed-infrared (FTIR) spectra investigated the vibrations and adsorption peak of the composites, thereby ascertaining the formation of reduced graphene oxide. In addition, diffuse reflectance spectroscopy (DRS) demonstrated an enhanced absorption in the visible region. The experimental investigations revealed that graphene oxide acted as charge collector and simultaneously facilitated surface adsorption and photo-sensitization. It could be deduced that BaTiO3-reduced graphene oxide composites are of significant interest the field of water purification through solar photocatalysis.

Synthesis and investigation of temperature effects on barium titanate (BaTiO3) nanostructural and electrical properties

In the present work, BaTiO3 samples were synthesized by sol–gel method and then they were coated on Si substrate for 30 min at 1500 rpm. The samples were finally calcined at T1 = 85 °C, T2 = 200 °C, T3 = 400 °C and T4 = 600 °C to investigate temperature effects on them. The nano structural and nano compositional properties of the samples were also investigated by using thermo gravimetric analysis, X-ray diffraction (XRD), scanning electron microscopy, energy dispersive X-ray, X-map and atomic force microscopy techniques. According to XRD technique, the particle’s sizes were 10–38 nm. The BaTiO3 particles size increased relatively with increasing temperature. According to Fourier transfer infrared radiation technique, the junctions between Ba, Ti and O were strong. In this research, current–voltage (I–V), capacitance–voltage (C–V) and current density–voltage (J–V) curves were used for determining temperature effects on electrical properties of BaTiO3 nanostructure. Dielectric constant and impedance (Z) of BaTiO3 samples were investigated, as well.

Effect of surface hydroxyl groups on the dispersion of ceramic powders

The effect of surface hydroxyl groups (OH) on the dispersity of ceramic powders was explored using the common ceramic powder barium titanate (BaTiO3) as the study model. To simulate the presence of OH on the powder, which is generally formed because of atmospheric storage, oxidative hydroxylation with hydrogen peroxide was used to produce and adjust the concentration of surface OH. Owing to the presence of a lot of surface OH, BaTiO3 particles aggregated because of hydrogen bonding and required a large amount of dispersant such as the ammonium salt of poly(acrylic acid) (PAA-NH4) for its dispersion stabilization. In addition, the commonly used binder poly(vinyl alcohol) (PVA) became more competitive with PAA-NH4 for adsorption onto the hydroxylated BaTiO3, thereby reducing the efficiency of the dispersant and impeding the dispersion of the powder.

Enhanced dielectric permittivity of BaTiO3/epoxy resin composites by particle alignment

Barium titanate (BaTiO3)/epoxy resin composites with a novel structure, in which the BaTiO3 particles were directionally aligned in the epoxy resin matrix, were fabricated using the ice-templating method. The effects of the filler particle alignment and the filler fraction on the dielectric permittivity as well as the dielectric loss of the composites were studied. The results show that the aligning filler particles can significantly improve the dielectric permittivity while maintaining the dielectric loss compared with the traditional composite structure (homogeneously distributed). Due to the feasibility of the enhancement of the dielectric properties of the composites, the particle alignment that is achieved via the ice-templating method can be used in the field of high energy density capacitors.