BaTiO3 Powders Research Articles

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.

Study of ferroelectric and piezoelectric response of heat-treated surfactant-based BaTiO3 nanopowder for high energy capacitors

Barium titanate (BaTiO3) nanopowder was synthesized by the alkoxide-hydroxide sol–gel process in an inert (N2) atmosphere. The effect of surfactant sodium dodecyl sulfate (SDS) concentration on the dispersion of BaTiO3 powder was studied at different sintering temperatures, under microwave heating. The phase and structural analysis revealed that the addition of surfactant did not affect the phase transformation of barium titanate. The best outcome was obtained in the case of 0.5 % surfactant-based BaTiO3. At 1100 °C sintering temperature, 0.5 % surfactant-based BaTiO3 exhibited a maximum density of 97.7 %, dielectric constant of 9488, the leading parameters of breakdown strength as 3.12 kV/cm, the figure of merit as 9.98 × 103, and the piezoelectric constant (d33) as 153 pC/N. Moreover, the energy density of 86 kJ/m3 with an energy efficiency of 27.43 % was attained at 1100 °C. For pure BaTiO3 nanopowder, the energy density and the energy efficiency were found as 66.85 kJ/m3 and 50.42 % at 1250 °C, respectively.

Major factors affecting the dielectric properties and reliability of solid stated reacted BaTiO3 powders for capacitor

ABSTRACT In this study, solid-state BaTiO3 was successfully synthesized after the disintegration of the starting materials (BaCO3 and TiO2) under various conditions. By analyzing the microstructure, tetragonality, crystallinity, and particle size distribution of the synthesized powder, the factors that affected the properties of the BaTiO3 solid-state synthetic powder were successfully identified. Furthermore, the changes in the dielectric constants (temperature characteristic coefficients) of the sintered specimens were investigated using each powder, according to the dielectric characteristics, high-temperature resistance, and temperature, to identify the direct and indirect relationships between the disintegration conditions, synthetic powders, and sintered specimens. Finally, optimal conditions for the uniform solid-state synthesis of BaTiO3 powder for multilayer ceramic capacitor production were derived.

Low-temperature solid-state synthesis of tetragonal BaTiO3 powders from Ba(OH)2 and H2TiO3

Low-temperature solid-state synthesis of tetragonal BaTiO3 powders from Ba(OH)2 and H2TiO3

Abnormal grain growth in BaTiO3 nanoceramics by oriented attachment mechanism

The abnormal grain growth (AGG) behaviour was reported during the solid-state sintering of a nano-sized BaTiO3 powder using the spark plasma sintering technique. Microstructural observations revealed that coarse crystals containing large amounts of faceted pores burst into formation within minutes. The results challenged the traditional views that sintering was predominated by the atom-diffusion related processes. Instead, the phenomena were explained to be resulted from the oriented attachment of smaller BaTiO3 grains. A modified two-sphere model for nanoceramic sintering was also proposed.

Simply and Controllably Syntheszing Micro-Nano Barium Titanate Ceramics

The micro-nanoBaTiO3 ceramics of different sizes have been prepared simply and controllably via a self-assembly sintering method. The effects and scopes of the application of this method in the controllable synthesis of the micro-nanoBaTiO3 ceramics are investigated. Through the given size of BaTiO3 powders and the combination way, the ceramics with different grain sizes, such as 400~500 nm, can be controllably synthesized. Therefore, the use of this method is conducive to the realization of the controllable synthesis of the micro-nanoBaTiO3 ceramics.

Direct current (dc) bias effect on the dielectric constant of Dy and Ho-doped BaTiO3-based ceramic and MLCCs

With the increasing demand for the miniaturization, high capacitance and high reliability of the Multilayer Ceramic Capacitor (MLCC), the thickness of single dielectric layer is less than 1 μm and the original partical size of the powder has reached the scale less than 300 nm. In this paper, BaTiO3 powder of various partical sizes (150–500 nm) was modified with Dy and Ho through a chemical coating method. The dense and uniform ceramics in accordance with EIA X7R-type temperature stability were sintered under low oxygen partial pressure and good dielectric properties of dielectric constant >2000 and dielectric loss <1% were obtained. The grain size effect on the dielectric properties under various dc-bias field were systematically investigated. It is found that the fine-grain ceramic exhibits a lower absolute change of the dielectric constant and a higher dc-bias stability. Furthermore, the modified 150 nm BaTiO3 powders was made into 1210-type MLCCs, and the dielectric behavior of the MLCCs with different dc-fields and ac-fields were study over −55 °C–125 °C. It is found that the ac electric field had a greater influence on the dielectric properties at room temperature and below, and the dielectric constant variation under a dc-bias field was also greatly advanced for the modified fine-grain MLCCs. The results provide a reference for the design of the next generation of BME-MLCCs.

Effects of annealing temperature on structural phase transition and microstructure evolution of hydrothermally synthesized barium titanate nanoparticles

Commercial hydrothermally synthesized BaTiO3 powder with a cubic structure was annealed in a temperature range of 650 °C–900 °C, and the cubic-tetragonal structure transition and microstructure evolution of the powder were investigated in relation to the annealing process. The BaTiO3 powder used had a cubic structure below an annealing temperature of 800 °C and a tetragonal structure above 850 °C. Particle growth occurred under a low activation energy of ∼33.2 kJ mol−1 because of the nanocrystalline size effect, while the crystallite size slightly decreased in the powder with the cubic structure and sharply increased in that with the tetragonal structure. This was because the OH group in the powder with the cubic structure influenced the lattice extension on the particle surface. This stabilized the cubic structure and reduced the crystal ordering, which retarded the crystallite size. When the annealing temperature was increased, the crystallite growth reduced the intrinsic strain and enhanced the tetragonality in the powder with the tetragonal structure as a result of the removal of the OH group.

Wrapping Assembly of BaTiO3 Nanoparticles with (Bi0.5Na0.5)TiO3 Nanosheets: A Novel Processing for Nanograined BT–BNT Complex Perovskite Relaxors

Hydrothermal syntheses of BaTiO3 (BT) nanoparticles and (Bi0.5Na0.5)TiO3 (BNT) nanosheets are explored to maximize the uniform distributions of the components in BT–BNT complex perovskite solid solution preparation. By introducing a “wrapping process,” which is a 2D nanosheet‐based process for preparing core–shell‐type assembly of the BT and BNT powder mixture, the solid solution formation and densification are accelerated effectively resulting in lowering the sintering temperature and homogeneous nanograined microstructure. The improved microstructure of the BT–BNT solid solution ceramics contributes to the enhancement in dielectric polarizations over a wide temperature range. Relaxor characteristics of the solid solutions, i.e., diffusivity of the ferroelectric–paraelectric transition, frequency dispersion of ε r′, and shift of T m with frequency deviation from the Curie–Weiss law, are determined. It is also confirmed that the BT–BNT samples prepared by the wrapping process exhibit stronger relaxor behavior compared to the conventionally prepared BT–BNT samples even in the identical chemical composition. These hydrothermal reaction‐based novel processing routes for the complex perovskite compositions are very effective to improve microstructure, sinterability, and dielectric properties.

Sintering Temperature Driven Structural, Dielectric, Ferroelectric, and Piezoelectric Properties of 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 Lead-Free Composites

Lead-free 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 composites have been synthesized via sol-gel chemical route. We have systematically investigated the influence of sintering temperature on the structural and electrical properties of the BZT-BCT composites. The 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 composites were prepared by combining Ba(Zr0.2Ti0.8)O3 (BZT) and (Ba0.7Ca0.3)TiO3 (BCT) powders and sintered at different temperatures 900-14000C. The electrical properties of BZT-BCT composites improve with increasing sintering temperature. The composites sintered at 1300 and 14000C exhibit enhanced ferroelectric properties with spontaneous polarization Ps ~ 11.2 μC/cm2 and 8.66 μC/cm2 respectively. The dielectric and piezoelectric properties of BZT-BCT composites also improve with increasing sintering temperature. The dielectric constant value εʹ ~ 2938, tan δ ~ 0.016 and piezoelectric co-efficient d33 ~ 278 pC/N were measured for BZT-BCT composite sintered at 14000C while observing a considerably high transition temperature of Tc ~ 1200C. The observed results are discussed in terms of structural and microstructural analysis as a function of sintering temperature.

Influence of particle size on 3D‐printed piezoelectric ceramics via digital light processing with furnace sintering

To improve the properties of BaTiO3 piezoelectric ceramics fabricated by 3D printing, effects of particle size were investigated on the properties of ceramic slurries and the electrical properties of BaTiO3 fabricated by Digital light processing (DLP) 3D printing method. It was found that the curing ability of the slurries decreased significantly when the particle size is close to the ultraviolet wavelength, while the viscosity kept decreasing with the increase of particle size. When the particle size in a range of submicron (d50<1 μm), the grain size of sintered ceramics decreased from 13.27 to 6.84 μm as particle size increasing. Moreover, the piezoelectric constant and relative permittivity of sintered ceramics were measured, and it turns out to reach 168.1 pC/N and 1512, respectively, while using the BaTiO3 powder with particle size of 993 nm. Finally, a cellular structural BaTiO3 ceramics was fabricated by using optimized powder and process parameters and packaged as a piezoelectric sensor, showing a good function of force-electricity conversion. These results demonstrate the feasibility of fabricating high-quality functional ceramics with designed geometry by DLP.

Effect of Sb2O3 Addition on Properties of BaTiO3 Ceramics

This research aimed to study the effect of Sb2O3 addition on the properties of BaTiO3 ceramics. Pure and doped BaTiO3 powders were synthesized by the mixed oxide method using BaCO3 and TiO2 as starting materials, and the Sb2O3 was added with x wt% (x = 0-2). The mixed powders were then calcined at 1200 °C for 4 h, before pressing into pellets and sintered at 1250 °C for 4 h. Pure and 0.4 wt% Sb2O3 doped BaTiO3 ceramics also showed the BaTiO3 phase with tetragonal structure. The 0.4 wt% Sb2O3 condition showed the highest tetragonality (c/a). When BaTiO3 was doped with Sb2O3 at more than 0.4 wt%, the tetragonality decreased. Decreasing tetragonality of the BaTiO3 lattice indicated the transforming structure from tetragonal to pseudo-cubic. Pure BaTiO3 ceramic showed the largest grain size of about 1.40 µm. With the addition of Sb2O3, the grain size reduced. The 0.4 wt% Sb2O3 condition showed the highest density value size of 5.10 g/cm3, and the highest dielectric constant at 10 kHz of about 4271 at Curie temperature (Tc = 112 °C). Dielectric loss of this condition decreased by about 50% compared to the pure BaTiO3 ceramic and the dielectric constant decreased with increasing frequency. The BaTiO3 ceramic was doped with Sb2O3 at higher than 0.4 wt%, the dielectric constant decreased and the peaks became increasingly flat due to these conditions transform to the pseudo-cubic lattice structure.

The Effect of Calcination Temperature on the Structural Properties of BaTiO&lt;sub&gt;3&lt;/sub&gt; and (Ba&lt;sub&gt;0.85&lt;/sub&gt;Ca&lt;sub&gt;0.15&lt;/sub&gt;)(Zr&lt;sub&gt;0.1&lt;/sub&gt;Ti&lt;sub&gt;0.9&lt;/sub&gt;)O&lt;sub&gt;3&lt;/sub&gt; Using the SSR Method

This paper studies how the various calcination temperatures affect the structural properties of Barium Titanate (BaTiO3) and (Ba0.85Ca0.15)(Zr0.1Ti0.9) (BCZT) using solid-state reaction methods. BaTiO3 and BCZT powders are calcined at various temperatures ranging from 1100°C–1300°C. Using X-ray diffraction, the phase formation, crystal structure and crystallite size of BaTiO3 and BCZT powders were determined. The cubic crystal structure has been formed for BaTiO3 and BCZT. At 1200°C, the reaction between BaCO3 and TiO2 was complete to produce BaTiO3 composition. For BCZT composition were not fully react based on the phase structure in XRD due to impurity peak. Next, the crystallite size of BaTiO3 powder becomes larger with increasing calcination temperature. Meanwhile, BCZT crystallite size becomes smaller when the calcination temperature is increased has discussed at the end of this paper.

Discrete Element Simulation of Ceramic Powder Processing

Abstract Discrete element modeling (DEM) was applied for simulating the powder packing dynamics during electrophoretic deposition of electrostatically stabilized ZrO2 (powder size 1 μm) and tape casting of BaTiO3 (powder size 0.3 μm) stabilized by polymer adsorption. The results indicate that a transition zone of ordering is supposed to exist ahead of the growth front of the solid sediment during electrophoretic deposition. Local variation of the shear rate in the tape casting process with increasing distance from the blade gives rise for the generation of particle clusters under low shear, and cluster disintegration (shear thinning) under high shear conditions. Thus, DEM simulation provides a detailed insight into local variations of particle interaction processes during consolidation which can be used for optimization of the shaping process of colloidal ceramic powder suspensions.

Electrocatalytic Properties of a BaTiO3/MWCNT Composite for Citric Acid Detection

Although barium titanate (BaTiO3) shows prominent dielectric properties for fabricating electronic devices, its utilization in electrochemical applications is limited. Thus, this study examined the potential of a BaTiO3-based composite in the detection of a food additive, i.e., citric acid. First, a submicron-scale BaTiO3 powder was synthesized using the solution combustion method. Then, a BaTiO3/multiwalled carbon nanotube (MWCNT) composite was hydrothermally synthesized at BaTiO3:MWCNT mass ratios of 1:1 and 2:1. This composite was used as a working electrode in a nonenzymatic sensor to evaluate its electrocatalytic activity. Cyclic voltammetric measurements revealed that the BaTiO3/MWCNT composite (2:1) exhibited the highest electrocatalytic activity. Reduction reactions were observed at applied voltages of approximately 0.02 and −0.67 V, whereas oxidation reactions were detected at −0.65 and 0.47 V. With acceptable sensitivity, decent selectivity, and fair stability, the BaTiO3/MWCNT composite (2:1) showed good potential for citric acid detection.

Effect of Sm2O3 addition on the dielectric behaviour of BaTiO3

BaTiO3 is a widely used ferroelectric ceramic having applications in transducers, capacitors, thermistors, non linear optics etc. BaTiO3 exhibits Curie temperature (Tc) of 120 °C. Recent research in BaTiO3 based thin films has resulted in a significant rise in their Tc. The most prominent increase in Tc has been reported in BaTiO3 – Sm2O3 system in which Sm2O3 nanorods were incorporated in BaTiO3 matrix resulting in the Tc ∼ 800 °C. Such a remarkable increase in the Tc was attributed to the high elastic modulus of Sm2O3 (E = 125 GPa) w.r.t. that of BaTiO3 (E = 67 GPa). Higher elastic modulus of the second phase resulted in the generation of strain in the matrix thereby delaying the onset of tetragonal – cubic transition. The improvement in the Tc of BaTiO3 thus opened possibilities of use of BaTiO3 based systems for high temperature piezoelectric applications. Since BaTiO3 based thin films exhibited a remarkable increase in the Tc, it needed to be studied if such a phenomenon could be replicated in bulk ceramics. Hence, BaTiO3 – Sm2O3 ceramics were prepared by the conventional ceramics processing route. Submicron-sized BaTiO3 and Sm2O3 powders were used as starting materials and compositions with Sm2O3 content varying between 5 and 30 wt% were prepared. BaTiO3 and Sm2O3 powders were milled using a jar mill for 48 h in ethanol followed by drying of slurries and room temperature uniaxial pellet pressing. Green pellets were sintered by pressureless sintering at 1350 °C for 4 h. X-ray diffraction (XRD) analysis of BaTiO3 and BaTiO3 – 5 wt% Sm2O3 ceramics confirmed the presence of tetragonal phase. However, further increase in Sm2O3 content resulted in the transformation of tetragonal BaTiO3 to cubic BaTiO3. Since cubic phase is centrosymmetric and cannot exhibit ferroelectricity, compositions with Sm2O3 > 5 wt% became redundant for any ferroelectric application. Moreover, BaTiO3 – 5 wt% Sm2O3 exhibited Tc of just 100 °C with lower dielectric constant thereby making this composition ineffective for high temperature piezoelectric application. While it had been anticipated that incorporation of Sm2O3 in bulk BaTiO3 ceramics would increase their Tc as in thin films, none of these compositions exhibited the anticipated behaviour. This paper discusses why BaTiO3 – Sm2O3 bulk ceramics failed to exhibit similar dielectric behaviour to their thin film counterparts in light of the phase formation, microstructure and dielectric behaviour.

Evaluation of Stereolithography-Based Additive Manufacturing Technology for BaTiO3 Ceramics at 465 nm

A piezoceramic BaTiO3 material that is difficult for 3D printing was tested with a homemade laser-based stereolithography (SLA) setup. The high light absorbance of BaTiO3 in the spectral range of 350–410 nm makes this material hardly usable with most commercial SLA 3D printers. The typical polymerization depth of BaTiO3 ceramic pastes in this spectral range hardly reaches 30–50 µm for 40 vol % powder loading. A spectral change to 465 nm was realized in this work via a robot-based experimental SLA setup to improve the 3D printing efficiency. The ceramic paste was prepared from a preconditioned commercial BaTiO3 powder and used for 3D printing. The paste’s polymerization was investigated with variation of powder fraction (10–55 vol %), speed of a laser beam (1–10 mm/s, at constant laser power), and a hatching spacing (100–1000 µm). The polymerization depths of over 100 µm were routinely reached with the 465 nm SLA for pastes having 55 vol % powder loading. The spectral shift from 350–410 nm spectral region to 465 nm reduced the light absorption by BaTiO3 and remedied the photopolymerization process, emphasizing the importance of comprehensive optical analysis of prospective powders in SLA technology. Two multi-layered objects were 3D-printed to demonstrate the positive effect of the spectral shift.

Synthesis of Tetragonal Batio3 Powder with Size and Dispersity Optimization Via Synergy Mechanisms of Combined Dispersants

Synthesis of Tetragonal Batio3 Powder with Size and Dispersity Optimization Via Synergy Mechanisms of Combined Dispersants

Electron Density Distribution and Microstructural Spherical Harmonic Calculation of Batio3 Powders and Ceramics

Electron Density Distribution and Microstructural Spherical Harmonic Calculation of Batio3 Powders and Ceramics

Sonochemical activation in aqueous medium for solid-state synthesis of BaTiO3 powders

BaTiO3-based oxide compounds are important ceramic materials for multilayer ceramic capacitors. In this paper, we report a sonochemical activation process of BaCO3 and TiO2 in an aqueous medium for the synthesis of BaTiO3 powders through a solid-state process. Owing to the physical and chemical effects of the ultrasonication in aqueous medium on the raw materials, BaTiO3 powders could be successfully synthesized at relatively low temperatures through a solid-state reaction, which was significantly enhanced as compared to the case in ethanol medium. Detailed investigations on the resulting BaTiO3 powders and ceramics were performed, and a model to understand the role of aqueous medium on the enhancement of the solid-state reaction was proposed in terms of Ba2+ ion leaching and zeta potential of TiO2, which are strongly affected by the pH of the aqueous medium. Our results are not only helpful for cost-effective synthesis of BaTiO3 through the highly reliable solid-state reaction process, but they also provide an understanding of the role of aqueous medium for the sonochemical process using raw materials with partial solubility in water.