Increase Of BaTiO3 Content Research Articles

Structural, optical, and morphological properties of PVC-BaTiO3 nanocomposite films

This work aims to fabricate barium titanate (BaTiO3) nanoparticles and study the effect of adding different contents of BaTiO3 nanoparticles on the structural, optical, and electrical properties of PVC polymer matrices. The PVC/BaTiO3 nanocomposite films were characterized by X-ray diffraction, FT-IR spectroscopy, and SEM. In addition, dielectric properties were studied within the frequency range of 0.1 KHz–6 MHZ. The XRD analysis reveals an amorphous nature of pure PVC with two characteristic peaks at 2θ = 17.09° and 2θ = 23.25°, and it reveals that BaTiO3 has sharp and narrow peaks. In PVC/BaTiO3 nanocomposite films, all XRD peaks of BaTiO3 appeared in all the samples with an increase in the average particle size from ∼46 nm to 55 nm. There is no shift of IR position in PVC bands, but the decreased intensity of some bands suggests complexation between PVC and BaTiO3. The UV–visible absorption spectrum of pure PVC has a band at λ = 278 nm. This band was shifted to 252 nm after adding BaTiO3 content. UV–visible transmission spectra demonstrate a decrease in the transmittance as an increase of BaTiO3 content from 89.23 % for pure PVC to 5.23 % for 0.1 wt% of BaTiO3. The values of the optical bandgap decrease with increasing BaTiO3 contents due to defect formation in PVC matrices. The optical parameters of the prepared nanocomposite films were also enhanced. The AC conductivity shows an increase with both frequency and BaTiO3 concentration, leading to enhanced movement of charge carriers and relaxation of interface polarization.

Effect of thermal annealing on dielectric property and thermal conductivity of Si3N4–BaTiO3 composite ceramics

Si3N4–BaTiO3 composite ceramics were prepared by hot pressing sintering. The effects of the amount of BaTiO3 and annealing process on the microstructure, phase composition, dielectric properties and thermal conductivity of Si3N4 composite ceramics were studied. With the increase of BaTiO3 content, the density and the dielectric performance of the Si3N4-based composite ceramics are improved, while the thermal conductivity is reduced. The annealing treatment can not only inhibit the growth of β-Si3N4, refine the grain, reduce the content of intercrystalline glass phase and porosity, but also promote the precipitation of hexagonal barium titanate, all of which are beneficial to increase the dielectric constant and decrease the dielectric loss, but will slightly reduce the thermal conductivity of Si3N4–BaTiO3 composite ceramic. The sample A2BT15 with 15% BaTiO3 sintered at 1750 °C for 2 h and annealed at 1300 °C exhibited the maximum dielectric constant (ε = 10.57), the minimum dielectric loss (tanδ = 9×10-4), a high relative density (98.8%) and an acceptable thermal conductivity (14.5 W·m-1·K-1). Therefore, the selection of appropriate BaTiO3 content and annealing process can regulate the dielectric property, thermal performance and mechanical property of Si3N4–BaTiO3 composite ceramics in a certain range.

Study of the Crystallization and structural behavior of Bismuth Barium Titanate Glass-Ceramics

Bismuth Barium titanate glass-ceramics with composition (100-x)Bi2O3-xBaTiO3 synthesized via controlled crystallization have been explored for their structural and optical properties. X-Ray Diffraction data clearly confirmed the presence of crystalline phases in the prepared glass-ceramics with orthorhombic Ba2Ti13O22 phase being the leading and stable one. Additionally, the commencement of hexagonal BaTiO3 phase has been found in higher compositions above x ≥ 20 with increase in BaTiO3 content. FTIR and Raman spectroscopy revealed the conversion of Non-bridging oxygen atoms (NBO's) to Bridging oxygen atoms (BO's) takes place when BaTiO3 content increases in the sample and thus resulting in compactness of the network. UV-Visible spectroscopy has been performed to calculate their optical band gap energies (Eg). An increase in optical band gap energy has been found and same has also been confirmed using Urbach energy approach. The lower values of Urbach energy propose the creation of (BO's), decrease in disorder and hence support structural stability of the system. The electronegativity and electronic polarizability values reveal the covalent character of glass-ceramic samples.

Effects of MWCNTs on the Tensile Properties and Thermal Conductivity of BaTiO3 /Epoxy Nanocomposites

This research studied the effects of modified BaTiO3 (BT) nanoparticles with coupling agent γ-APS (0.5wt. %) on the tensile and thermal conductivity of epoxy nanocomposites with respect to content (0.25, 0.5, 0.75, 1, 3 and 5wt. %). Multiwall carbon nanotubes (MWCNTs) at different concentration (0.2, 0.4, 0.8 and 1 wt. %) were added to the BaTiO3/epoxy nanocomposites. The influence of MWCNTs on the tensile properties and thermal conductivity was investigated. The tensile strength and Young’s modulus of BaTiO3/epoxy nanocomposites film were increased at up to 3 wt. % of added BT, but adding BT at more than 3 wt.% decreased the strength of epoxy. The tensile strength was increased with increasing MWCNTs content from 32 MPa for pure epoxy to the value 56.8 MPa for 1wt. % of MWCNTs content. The thermal conductivity of BaTiO3/epoxy nanocomposites improved with increase of BT content. At 3wt. % and 5wt. % of BaTiO3 the thermal conductivity of nanocomposites decreased. The increase of MWCNTs concentration from 0.2 wt. % to 1 wt. % resulted in a thermal conductivity enhancement.

Enhanced magnetic, ferroelectric, and photocatalytic properties of (1-x)BiFeO3-xBaTiO3 (0.0 ≤ x ≤ 0.4) powders

The magnetic, ferroelectric, and photocatalytic properties of (1-x)BiFeO3-xBaTiO3 (0.0 ≤ x ≤ 0.4) powders synthesized by sol-gel method have been investigated. X-ray diffractometry confirms that the phase of the samples changed from rhombohedral to cubic with the increase in BaTiO3 content. The grain size decreases and the particle shape becomes homogeneous with the introduction of BaTiO3. BaTiO3 substitution enhances the multiferroic properties of the ceramics and the maximum remnant magnetization (0.261 emu/g) and remnant polarization (20 μC/cm2) have acquired in 0.8BiFeO3-0.2BaTiO3 and 0.7BiFeO3-0.3BaTiO3, respectively. The absorbance in ultraviolet and visible light regions is improved obviously for powder with x = 0.3. The energy band gap of the samples decreases from 2.06 eV to 1.57 eV with the introduction of BaTiO3, indicating that the excitation rate of photogenerated electron-hole pairs is improved. The highest methylene blue degradation efficiency of ~62% within 3 h under the visible light is achieved in the 0.7BiFeO3-0.3BaTiO3 which can be attributed to its suitable energy band gap and large remnant polarization.

Preparation and characterization of BaCo0.5Nb0.5O3-based new high temperature NTC sensitive ceramics

A new type of high temperature NTC thermal sensitive ceramics BaCoxNbxTi(1−2x)O3 (BCNT) was synthesized via a solid-state reaction process. The as-prepared ceramics were obtained by sintering at 1300 °C for 1 h in air. According to the XRD and SEM analysis, BCNT form a solid solution with cubic phase, and the content of BaTiO3 (BT) has insignificant influence on the mean grain size of the ceramics. The BaCo0.5Nb0.5O3 (BCN) based materials show typical NTC effect in the whole temperature measuring range (25–500 °C). The room temperature resistivity (ρ25), thermal constant (B25/85) and activation energy (Ea) increase monotonously with the increase of BT content. The TG-DSC results show that there is no phase transition in the temperature range from 25 to 1000 °C, which indicate that the structure of the BCN-based ceramics is stable at high temperature.

Study on properties of barium titanate/polyethersulfone dielectric composites prepared by physical dispersion method

Composite materials applied to capacitors with high dielectric constant, low dielectric loss and outstanding thermal stability are concerned widely in the field of dielectrics. So committed to the development of dielectric materials with excellent performance is the key factor. In this work, the barium titanate/polyether sulfone (BaTiO3/PES) composite films were prepared by a physical dispersion technology, which utilized a ball milling machine by high-speed circulation, scattered the PES solution contained BaTiO3 in deionized water with the aid of a surfactant. Then, the BaTiO3/PES composite films were obtained through a series of operations, containing reclaimed organic solvent, washed with deionized water, filtered, dried and hot pressed. The morphology of the BaTiO3/PES emulsion was investigated by TEM and SEM. The results showed that the BaTiO3 particles were covered in the PES resin matrix homogeneously. For 50 wt% BaTiO3 reinforced PES composite film. The dielectric constant increased by ~ 227% compared with pure PES resin (4.1 at 1 kHz) and the dielectric loss maintained around 10−2 magnitude, which performed better dielectric properties. The tensile strength of 10 wt% BaTiO3/PES composite films (72 MPa) reached the highest value in comparison with those of pure PES (58 MPa) due to the strengthened interaction between particles and matrix. Further increase of BaTiO3 content, the tensile strength and elongation at break decreased slightly but remained an excellent flexibility from the PES matrix. The temperature at weight loss 5% (T5%) of composite film with 40 wt% of BaTiO3 content reached up to 503 °C in N2 atmosphere. All the BaTiO3/PES composite films performed the concentrated glass transition temperature (Tg) around 229 °C. In sum, excellent thermal stability and dielectric properties would make the BaTiO3/PES composite films become the fine potential candidates for dielectric composites in the capacitors.

Detection of deformation induced electromagnetic radiation from cement- barium titanate composite under impact loading

Electromagnetic radiation (EMR) responses from cement–BaTiO3 (BT) composites under impact loading have been presented in this paper. The bulk density, dielectric constant and piezoelectric charge coefficient of the cement-BT composites are observed to increase while the loss tangent decreases with increase in BT content in the composites. Measurements have been carried out using cylindrical, semi-cylindrical and quarter cylindrical antennae. Marked enhancement in the values of EMR voltage for all experiments at different heights of impact and with different antennae is observed as the content of BT is increased from 5% to 40% in the cement–BT composites. The EMR voltage increases, respectively from 0.58 V to 1.16 V, 384–732 mV and 259–520 mV for cylindrical antenna, semi-cylindrical antenna and quarter cylindrical antenna with the increase in BT content from 5% to 40% in cement–BT composites at the same level of impact (height of impact = 21 cm). Also average EMR energy release rate increases from 0.00007 V2–sec/sec to 0.00047 V2–sec/sec, 0.000065 V2 – sec/sec to 0.000214 V2 – sec/sec and 0.000032 V2 – sec/sec to 0.000135 V2 – sec/sec with the increase in BT content from 5% to 40% in cement–BT composites impacted from a height of 21 cm as measured by cylindrical antenna, semi-cylindrical antenna and quarter cylindrical antenna respectively. The EMR voltage is observed to decrease smoothly initially and then attain constancy with increase in distance of measurement location from the sample. In addition, the EMR responses were found to be proportional to the height of impact in all the cement–BT composites indicating that EMR measurement technique can effectively be used for structural health monitoring.

Structure and Charge Density Properties of (1 − x)(Na1−y K y NbO3)-xBaTiO3 Lead-Free Ceramic Solid Solution

(1 − x)(Na1−yKy)NbO3-xBaTiO3 (abbreviated as NKN-BT, x = 0.1, 0.2; y = 0.01, 0.05) ceramics were synthesized by the solid-state reaction method. Powder x-ray diffraction analysis in combination with the profile refinement method was employed for quantitative phase analysis and structural refinement. The x-ray diffraction study shows that phase transition occurs from tetragonal to distorted cubic with the compositions between x = 0.1 and x = 0.2. The spatial arrangements of the electron distribution and bonding nature of the samples have been analyzed through the maximum entropy method. The optical band gap energy of the prepared solid solutions has been determined using UV-visible spectrophotometry. The optical band gap energy of the solid solutions decreases with the increase in BaTiO3 content. The elemental composition of these ceramics has been studied using energy dispersive x-ray analysis and the microstructure has been examined by scanning electron microscopy. The piezoelectric coefficient (d33) measurement of the ceramics shows the enhancement of piezoelectric properties in the tetragonal phase. The maximum value of the piezoelectric coefficient (d33) obtained for the solid solution is 120 pC/N. With increasing BaTiO3 content in the solid solutions, the ferroelectric behavior weakens.

Electromagnetic properties and microwave-absorption properties of BaTiO3/BaZn2Fe16O27 composite in 2–18 GHz

BaTiO3/BaZn2Fe16O27 composites were prepared by traditional solid state method, BaTiO3 nano particles were coated around with the BaZn2Fe16O27 ferrite with hexagonal plate structure. The prepared composite particles were characterized with X-ray diffraction, scanning electron microscopy, and vector network analyzer. With the increase of BaTiO3 content, the complex permittivity of the composites increases, while the complex permeability decreases; The sharp peaks of the magnetic loss appear at 8.72 and 14.0 GHz, and the peak values are 1.64 and 0.69, respectively, when the mole ratio of BaZn2Fe16O27/BaTiO3 is 10:5; The matching thickness of BaTiO3/BaZn2Fe16O27 composites is 2.5 mm when the mole ratio of BaZn2Fe16O27/BaTiO3 is 10:5, and the minimum reflection loss reaches −33.49 dB at 8.56 GHz; There are more than one loss peak appeared in the reflection loss cures, and the effective absorption frequency (RL < −10 dB) ranges from 7.92 to 14.96 GHz with a thickness of 3 mm.

Magnetic properties of mixed spinel BaTiO3-NiFe2O4 composites

Solid solution of nickel ferrite (NiFe2O4) and barium titanate (BaTiO3), (100-x)BaTiO3–(x) NiFe2O4 has been prepared by solid state reaction. Compressive strain is developed in NiFe2O4 due to mutual structural interaction across the interface of NiFe2O4 and BaTiO3 phases. Quantitative analysis of X-ray diffraction and X-ray photo electron spectrum suggest mixed spinel structure of NiFe2O4. A systematic study of composition dependence of composite indicates BaTiO3 causes a random distribution of Fe and Ni cations among octahedral and tetrahedral sites during non-equilibrium growth of NiFe2O4. The degree of inversion decreases monotonically from 0.97 to 0.75 with increase of BaTiO3 content. Temperature dependence of magnetization has been analyzed by four sublattice model to describe complex magnetic exchange interactions in mixed spinel phase. Curie temperature and saturation magnetization decrease with increase of BaTiO3 concentration. Enhancement of strain and larger occupancy of Ni2+ at tetrahedral site increase coercivity up to 200 Oe. Magnetostructual coupling induced by BaTiO3 improves coercivity in NiFe2O4. An increase in the demagnetization and homogeneity in magnetization process in NiFe2O4 is observed due to the interaction with diamagnetic BaTiO3.

Multiferroic Properties of (Bi0.9Gd0.1FeO)1−x (BaTiO3) x Ceramics

Conventional solid-state reaction method has been employed for the synthesis of polycrystalline (Bi0.9Gd0.1FeO)1−x(BaTiO3)x for x=0.1, 0.2 and 0.3, ceramics samples. The effect of BaTiO3 content on the multiferroic properties of Gd-doped BiFeO3 ceramics has been presented. Pure perovskite phase with high density has been obtained by optimizing the synthesis approach, calcination and sintering strategies. Structural analysis carried out using X-ray diffraction confirms the formation of desired morphotropic phase. The dielectric properties have been investigated at different concentration of BaTiO3 as function of temperature, revealing that by increasing the BaTiO3 content dielectric constant increases while dielectric losses decrease. Magnetic study shows that initially saturation magnetization increases with increase in BaTiO3 content up to x=0.1; however, afterwards it decreases for higher concentration of BaTiO3. According to ferroelectric measurements, PE loops (with low coercive field) are observed at room temperature. The remnant polarization (Pr) has been found to be 0.169, 0.619 and 0.760 μC/cm2, respectively, for samples with x=0.1, 0.2 and 0.3. Magnetoelectric coupling in as-synthesized samples has been indirectly deduced by an anomaly observed at magnetic transition temperature.

MORPHOTROPIC PHASE BOUNDARY AND DIELECTRIC RELAXATION STUDY OF (Bi0.5Na0.5)TiO3–BaTiO3 LEAD-FREE CERAMIC

We report the temperature and frequency dependence impedance spectroscopy of (1 - x) ( Bi 0.5 Na 0.5) TiO 3-x BaTiO 3 (abbreviated as BNT–BT) ceramics with 0 ≤ x ≤ 0.07 prepared by conventional solid-state route. X-ray diffraction analysis indicated that a solid solution is formed when BaTiO3 diffuses into the (Bi0.5Na0.5)TiO3 lattice and a morphotropic phase boundary between rhombohedral and tetragonal locates at x = 0.07. The microstructure indicated that the grain size reduces and the shape changes from rectangular to quasi-spherical with increase in BaTiO3 content. Complex Impedance Spectroscopy analysis suggested the presence of temperature-dependent relaxation process in the materials. The modulus mechanism indicated the non-Debye type of conductivity relaxation in the materials, which is supported by impedance data. The activation energies have been calculated from impedance, electric modulus studies and dc conductivity which suggests that the conductions are ionic in nature. The activation energy increases with increase of BT content up to x = 0.05 and decreases at x = 0.07 which also indicates the presence of morphotropic phase boundary at x = 0.07.

Enhanced low-field-magnetoresistance and electro-magnetic behavior of La0.7Sr0.3MnO3/BaTiO3 composites

We report the structural, magentoresistance and electro-magnetic properties of ferromagnet–ferroelectric–type (1−x)La0.7Sr0.3MnO3/xBaTiO3 (with x=0.0%, 3.0%, 6.0%, 12%, 15.0% and 18.0%, in wt%) composites fabricated through a solid-state reaction method combined with a high energy milling method. The insulator–metal transition temperature shifts to a lower temperature and resistivity increases while the feromagnetic–paramagnetic transition temperature remains almost unchanged with the increase of BaTiO3 content. Magnetoresistance of the composites at an applied magnetic field H=3 kOe is enhanced in the wide temperature ranges with the introduction of BaTiO3, which could be explained by the enhanced spin polarized tunneling effect induced by the introduction of BaTiO3. The low-field magnetoresistance of the composite is analyzed in the light of a phenomenological model based on the spin polarized tunneling at the grain boundaries. Furthermore, the temperature dependence of resistivity for this series has been best-fitted by using the adiabatic small polaron and variable range hopping models. These models may be used to explain effect of BTO on the electronic transport properties on high temperature paramagnetic insulating region.

Thermal and electrical properties of nitrile‐containing polyimide/BaTiO3 composite films

AbstractPolyimide composite films were prepared by mixing the BaTiO3 particles into poly(amic acid) solution followed by film casting and thermal imidization under controlled temperature conditions. The poly(amic acid) was synthesized by solution polycondensation reaction of 4,4′‐oxydiphthalic anhydride with 2,6‐bis(4‐aminophenoxy)benzonitrile, using N‐methyl‐2‐pyrrolidone as solvent. The surface of BaTiO3 particles was modified by treating with an aminosilane coupling agent, 3‐aminopropyltriethoxysilane. Fourier transform infrared spectroscopy, X‐ray diffraction and scanning electron microscopy were used to characterize the structure and properties of the composites. The influence of BaTiO3 content on the composite film properties was evidenced. The films exhibited good thermal stability having the initial decomposition temperature above 520°C. They had stable dielectric properties over large intervals of temperature and frequency. The dielectric constant and the dielectric loss increased with the increase of BaTiO3 content. The dynamic mechanical analysis and dielectric spectroscopy revealed subglass transitions γ and β. At higher temperature an α‐relaxation that corresponds to the glass transition and a conductivity process were evidenced. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers

Dielectric properties of polymer/ceramic composites based on thermosetting polymers

A series of thermosetting polymer/ceramic composites were prepared. Three kinds of thermosetting polymers, i.e. cyanate resin, bismaleimide resin, and epoxy resin, were used as matrixes, and BaTiO3 particles were as fillers. The dielectric properties of these composites were investigated. Experimental data of the dielectric constants were fitted to several theoretical equations in order to obtain the best-fitting equations of the dielectric constants of these composites. The result indicates that the dielectric constants of composites all increase with the increase of BaTiO3 content. Using bismaleimide resin and epoxy resin as matrixes, the dielectric losses both increase obviously as the amount of BaTiO3 particles is increased, but the dielectric loss of cyanate/BaTiO3 composite decreases. With the increase of the frequency, the variation ranges of the dielectric constant and dielectric loss of cyanate/BaTiO3 composite are both the smallest. The predications of the effective dielectric constants by Lichterecker mixing rule are in good agreement with experiment data.

Effect of sintering temperature on electrical transport in La0.67 Ca0.33 MnO3/BaTiO3composites

It is shown that the electrical transport in ferromagnet–ferroelectric–type La0.67Ca0.33MnO3/BaTiO3 composites fabricated by the sol–gel method strongly depends on sintering temperature (Ts). For the Ts > 1000 °C samples, the insulator–metal transition temperature (TIM) decreases with increasing BaTiO3 content and the magnetoresistance (MR) is enhanced at low temperature (T < TIM). For the Ts = 1000 °C samples, the TIM value initially increases with an increase of BaTiO3 content and thereafter it decreases as BaTiO3 content further increases. For the Ts = 900 °C samples, the TIM value increases throughout the increase in BaTiO3 content and MR is enhanced over the whole temperature range studied. The experimental results have been discussed in terms of the magnetoelectric coupling effect and the interfacial diffusion reaction, especially at grain boundaries.