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Barium-titanium-peroxo type amorphous materials gained importance with the advent of wet-chemical methods for the production of crystalline perovskite barium titanate (BaTiO 3) electroceramics. In this paper, the chemical nature of the barium-titanium-peroxo precursor was determined by means of elemental (EPMA), spectroscopic (FT-IR and FT-Raman), XRD and thermal (DSC and TGA/DTA) analyses. Several synthesis parameters such as the barium source, the peroxide treatment time, the reaction temperature and the reaction time were investigated. The precursor was also thermally treated at varying temperatures between 30 °C and 1000 °C. Relatively high reaction temperatures are detrimental to the Ba∙O∙Ti structure, resulting in plain TiO 2 formation. Though relatively low temperatures (ice bath) are needed to suppress unwanted TiOCl 2 , ambient synthesis conditions and short reaction time (2 h) resulted in the desired single-source properties, i.e. amorphous Ba∙O∙Ti-peroxo structure with Ba/Ti ratio of unity (1.04 ± 0.04). The addition of an extra stirring step during H 2 O 2 addition lowered the chance of carbonate incorporation in the precursor. Thermal analysis under air and nitrogen atmosphere was performed and a stoichiometric formula of Ba 2,08 Ti 2 O(O 2) 1,9 (OH) 5,3 ∙3,1H 2 O was calculated, which was in very good agreement with literature data. The barium-titanium-peroxo-hydroxide material proved to be an excellent single-source precursor. Phase-pure, highly crystalline and facetted, stoichiometric BaTiO 3 particles with differently crystallographically oriented facets were obtained via the molten-salt solid-state method ({100} or {111} oriented facets) as well as the hydrothermal route ({100} oriented facets). [ABSTRACT FROM AUTHOR]

The structural, microstructural, dielectric, optical, ferroelectric, and magnetic properties of cobalt doped barium calcium titanate (BCT) (Ba 0.80 Ca 0.20 Ti 1-x Co x O 3 with x = 0.000, 0.005, 0.010, 0.015, and 0.020) ceramics have been reported in this paper. The ceramic samples were prepared by the conventional solid-state reaction method. For all of the prepared samples, the tetragonal structure with the space group P 4 mm has been confirmed using the refinement method through Rietveld refinement of X-ray diffraction patterns. Field Emission Scanning Electron Microscopy (FESEM) micrographs revealed that the average particle size exists in micrometre range (0.3–0.8) μm. Optical studies revealed a gradual decrease in the energy bandgap from 3.31 eV to 2.71 eV with increasing doping concentration. A decreasing trend was observed in the dielectric characteristics of the material with changing frequencies at room temperature. Ferroelectric (P-E loops) analysis displayed an increase in both remnant polarization and maximum polarization of the ceramic with the increasing applied electric field. The highest value for the energy storage efficiency (η) was calculated to be 20.51 %. Magnetic analysis conducted at room temperature revealed the enhancement in ferromagnetism with the increase in doping concentration. [ABSTRACT FROM AUTHOR]

Electrocaloric refrigeration shows the merits of environmental safeguarding, large efficiency, easy combination, and miniaturization as a novel solid-state refrigeration technique. In this paper, Sn4+ is doped into the B site of BLNT ceramics. By adjusting the doping content, the T-C phase transition peak was successfully shifted to room temperature and promoted the formation of relaxor ferroelectrics, resulting in a wider operating temperature range (T span) and improved adiabatic temperature change (ΔT). A comprehensive study was conducted on the crystal structure, surface morphology, dielectric properties, ferroelectricity, and electrical properties of BLNTS ceramics with varying levels of Sn4+ doping. Wherein, when the doping amount is 5Sn, a maximum adiabatic temperature change value (ΔT max) of 1.14 K was obtained, and the temperature span (T span) reached 45 °C (T span is defined as ΔT ≥ 80 % ΔT max). This work proposes a high-performance environmentally friendly electrocaloric effect (ECE) material suitable for solid-state cooling applications. [ABSTRACT FROM AUTHOR]

Joining of barium titanate (BaTiO 3 , BT) ceramics to metals plays an important role in their wide applications. However, conventional joining methods, including solid state diffusion joining and liquid state joining, have several drawbacks. In this paper, BT ceramic was flash joined to NiCrFe medium-entropy alloy (MEA) in seconds with an electric field (E-field) using current density of 10–80 mA/mm2 at 700–1000 °C. Shear strength of the joint first increased with applied current density and dwell time of the E-field and then decreased. It exceeded 40 MPa when the temperature was above 900 °C with current density of 60 mA/mm2 for 60 s. Both the real part (ε') and imaginary part (ε ") of complex permittivity of the joined sample were larger than those of the as-sintered BT ceramic at high frequency range. Microstructure of the joint suggests that a layer of chromium oxide was formed at faying surfaces, achieving effective bonding of BT and MEA. This research provides an efficient method for the manufacturing of BT based devices. [ABSTRACT FROM AUTHOR]

Amorphous films have excellent breakdown strength and energy storage efficiency, and have broad application prospects in dielectric film capacitors. However, its low polarization greatly limits the increase of energy storage density. In this paper, (Ba 0.92-x Bi 0.08 La x)(Ti 0.96-0.5x Ni 0.04+0.5x)O 3 (BBLTN) amorphous films were fabricated by sol-gel method. The effects of Bi, Ni and La ion doping on the electrical properties and energy storage properties of the films were studied. When x = 0.04, the film can produce an ultra-high recoverable energy storage density of 121.7 J cm−3 and an efficiency of 70.6%, and possesses outstanding stability at 20 °C–130 °C and 1-105 cycles. Combined with X-ray photoelectron spectroscopy analysis, researchers believe that the improvement of energy storage performance may be related to the dipoles formed by N i N i.. and T i T i ′ defects induced by multi-ion doping. This contribution provides a feasible way for the research of high-performance dielectric film capacitors. [ABSTRACT FROM AUTHOR]

With the trend of electronic information technology towards miniaturization, integration and intelligence, higher requirements are put forward for the performance of dielectric ceramic materials. In this paper, a series of doped samples Sm 2 O 3 -xZnO (x = 0, 0.1, 0.2, 0.4, 0.6, 0.8) were successfully prepared by the traditional solid state reaction method, and the complex dielectric properties of the ceramic samples were investigated as a function of temperature (100 K–400 K) and frequency (102–106 Hz) separately. A new phase Zn 6.76 Sm 2.58 O 10.6 was found in all samples, and all samples were complex. At a higher temperature, 350 K, with the increase of ZnO doping content, the maximum dielectric constant is 434.7, the dielectric loss is as low as 0.0098, and the dielectric performance is significantly increased compared with room temperature. UV–Vis DRS test showed that the absorbance of the sample increased with the increase of ZnO content, and the side reaction showed that the dielectric constant and dielectric loss of the sample were improved under the action of UV light. These provide an experimental basis for the application of samarium based dielectric ceramics. [ABSTRACT FROM AUTHOR]

Dielectric elastomers have been widely used in flexible actuators, artificial muscles, soft generators, etc. However, there are still challenges in fabrication of dielectric elastomers with enhanced dielectric and mechanical properties through simple and environmentally friendly compound method. In this paper, graphene nanoplatelets (GNPs) and BaTiO 3 (BT) hybrid nanofillers are prepared by co-ball milling and then introduced into fluorosilicone rubber (FSR) to obtain composites with improved dielectric and mechanical properties. The X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscope results confirm the successfully exfoliation of GNP. With the increase of GNP content, the tensile strength and dielectric constant of FSR/GNP/BT nanocomposites both increase without the sacrifice of flexibility, while the dielectric loss tangent can be kept as low as 10−2 magnitude. The FSR-G7B30-BM composite exhibits a dielectric constant of 14.54 at 100 Hz, and the dielectric loss tangent of 0.016 at 100 Hz. Besides, the FSR-G7B30-BM composite displays the tensile strength of 1.19 MPa, and elongation at break of 332.12%. This work provides a facile strategy to design dielectric elastomers, which shows promising applications in modern electronic devices. [Display omitted] • The ball milling of BT could generate temporary potentials, which is beneficial for the activation and exfoliation of GNPs. • The incorporation of the prepared GNP/BT hybrids into the FSR matrix concurrently improved the dielectric and mechanical properties of the composites. • This study provides a simple strategy to not only exfoliate layered materials but also design dielectric elastomers applied in electric devices. [ABSTRACT FROM AUTHOR]

In this paper, the effect of rare-earth dopants (RE: Ce, Eu, Tb, Dy, and Er) in barium titanate (BT) on the shaping, sintering and microstructure was studied aimed mainly at selecting appropriate dopant for densification delaying while preserving optimal BT characteristics. The addition of dopant oxides into suspension resulted in the reduction of the deposition kinetics. The relative density of doped green bodies was lower than pure BT and decreased with dopant concentration. Only Ce enhanced green density up to 2%. The sintering process was studied using high-temperature dilatometry. The hindering densification caused by dopants was observed, but only 5 wt % of Tb and Er in BT shifted the onset of sintering to higher temperatures that has the potential applicability of these materials in layered ceramic harvesters. The significant positive impact of doping on the microstructure was attained almost in all cases manifesting themselves in higher sintered densities and markedly lower mean grain size compared to pure BT. The XRD and Raman spectroscopy analyses confirmed incorporation of the dopants into the perovskite structure and no significant existence of RE-enriched secondary phases in the microstructure. [ABSTRACT FROM AUTHOR]

NaNbO 3 -based lead-free ferroelectric ceramics are considered to be one of the most promising energy storage materials. In this paper, The (1- x)Na(Nb 0 · 95 Ta 0.05)O 3 - x (Bi 0 · 5 Na 0.5)TiO 3 ceramics have been investigated in detail. The SEM images presented that the addition of BNT obviously improved the bulk densities which reached a maximum at x = 0.4, corresponding to a high breakdown field strength of 240 kV/cm. The XRD patterns showed that the strongest diffraction peak was observed in the case of x = 0.4 and 2 θ = 33.2°, implying that the two phases formed a superior mutual solubility, because of which a significant polarization intensity of 38.2 μC/cm2 was obtained. As a result, the 0.6NaNbO 3 -0.4(Bi 0 · 5 Na 0.5)TiO 3 ceramics exhibited an excellent discharge energy density of 3.607 J/cm3, while the energy storage efficiency was calculated to be 72%. [ABSTRACT FROM AUTHOR]

The fabrication of barium titanate (BaTiO 3) lead-free piezoelectric ceramics using additive manufacturing technology, especially digital light processing (DLP), has been gaining a growing interest for electrical applications. The particle size of the ceramic powders plays a key factor on the performance of sintered ceramic components. In this paper, BaTiO 3 ceramic components were fabricated by adopting different suspensions filled with the submicron powder particle size of 200 nm, 500 nm and 600 nm, respectively. Subsequently, the effects of particle size on the rheological properties and photopolymerization behaviors of the suspensions, as well as the density, grain size, piezoelectric and dielectric properties of the ceramic components, were investigated. The result indicated that the suspensions with the coarsest powder showed the lowest viscosity and the highest cure depth; when the grain size distributed in submicron range, the piezoelectric constant (d 33) and relative permittivity (ε r) of sintered BaTiO 3 ceramic are direct positively correlated to the grain size. The value of ε r and d 33 were related with domain structure affected by grain size. This work can provide a potential valuable guidance for researchers in selecting suitable BaTiO 3 powders to obtain high-performance piezoelectric ceramic components when using the DLP process. [ABSTRACT FROM AUTHOR]

Humidity sensors are often used in industries where humidity levels must be monitored due to their possible effects on the manufacturing processes and products. These sensors must possess high sensitivity that can detect changes in the environment's humidity level. This paper presents a novel technique to improve the sensing performance of humidity sensors by varying the microstructure of the BaTiO 3 humidity sensing layers by optimizing the mixing ratios of the bimodal inks deposited by the inkjet printing technique. By varying the mixing ratio of bimodal inks, the surface area, pore size, and packing density of the humidity sensing layers were modulated because of the incorporation of smaller particles into larger particles. The optimal sensor was produced by a 70:30 mixing ratio due to its higher surface area, which allowed a higher area for water adsorption and therefore improved the humidity sensitivity. Microstructural analyses, such as Focused-Ion-Beam Field-Emission Scanning Electron Microscope (FIB FE-SEM), image analysis, and Brunauer–Emmett–Teller (BET) were performed to examine the microstructural differences of the sensors. The fully inkjet-printed BaTiO 3 capacitive sensors, which had the optimal mixing ratio, exhibited a high sensitivity of 5.75 × 105 pF/%RH, which exceeded that of most reported humidity sensors, good repeatability, a linearity of 0.989, an acceptable response and recovery time of 41 s and 34 s, respectively, low hysteresis, and good stability over a long period of time. The fabricated BaTiO 3 -based capacitive humidity sensor exhibited an outstanding performance that can be utilized toward various applications. [ABSTRACT FROM AUTHOR]

This paper reports the first fabrication of high-entropy Ba(Ti,Hf,Zr,Fe,Sn)O 3 films on fluorine-doped tin oxide substrates through spin coating and hydrothermal synthesis. A homogeneous distribution of all constituent elements was observed through energy-dispersive x-ray spectroscopy mapping. High distortion (approximately 1.7%) of the lattice structure was caused by the underlying substrate and partial substitution of Ti with other larger elements of Hf, Zr, Fe, and Sn on B sites. Two types of Ba(Ti,Hf,Zr,Fe,Sn)O 3 films were studied: high-density and slightly textured polycrystalline particles (Sample A), and randomly distributed [110]-oriented nanorods with marginal crystallinity (Sample B). In the piezoelectric experiment, Samples A and B substantially outperformed the medium-entropy oxide (MEO) samples and single-crystal ZnO bulk. Sample A also exhibited the highest piezoelectric coefficient (d 33 ∼ 60 pm/V) among all studied samples. Its superior performance was attributable to a combination of high crystallinity, strong out-of-plane distortion, slightly textured polycrystalline structures, and cocktail effects. Furthermore, enhanced piezoelectricity was achieved after poling for the high-entropy oxide (HEO) and MEO samples, indicating their ferroelectric effect. The d 33 of Sample A more than doubled (≈126.7 pm∙V−1), and the increase was substantially higher than that of Sample B. Our HEO samples have promise for use in piezoelectric- and ferroelectric-related applications. [ABSTRACT FROM AUTHOR]

In the present paper, synthesis and characterizations of flexible dielectric and ferroelectric polymer films combining different ratios of graphene, barium titanate and polydimethylsiloxane are presented. Broad range of characterization techniques were carried out to confirm their, morphological, structural, chemical, thermal and mechanical (flexibility, stretching, bending and twisting) characteristics. Dielectric studies showed that a high dielectric constant of the nanocomposite was dependent on the ratio of graphene:bariumtitanate:polydimethylsiloxane, showing that ratio of 15:25:100 had a high dielectric constant at high frequency range and the ratio 15:30:100 at the low frequency range. At 2 Hz the ratio 15:30:100 showed a dielectric constant of 116.9 which decreased to 30.6 at 2 MHz, thus showing capacitive nature at full frequency range. Meanwhile dielectric loss was very low i.e., 1.3 at 20 Hz and 0.02 at 2 MHz and AC conductivity was 1.6 × 10−7 S/m. Ferroelectric properties like energy density, energy loss and efficiency were calculated and compared. At an electric field of 0.92 kV/cm, remanant polarization and coercive field were 3.9 × 10−4 μC/cm2 and15.82 kV/cm, respectively. Energy density of 0.64 J/m3, energy loss 0.358 J/m3 and efficiency 64.2% were confirmed respectively. Results indicate that the nanocomposite films having desirable performances such as flexibility, thermal stability, high dielectric constant, high energy density are good candidates to be considered in energy storage and memory device applications. [ABSTRACT FROM AUTHOR]

Barium titanate ceramic is frequently used as a ferroelectric material and can be applied in the pulse power field in energy storage devices. Its properties, including dielectric, ferroelectric, and energy storage properties, can be significantly improved through doping. In this work, we prepared a series of (1- x)Ba 0.65 Sr 0.245 Bi 0.07 TiO 3 - x ZnO (x = 0.005, 0.01, 0.02, 0.03) lead-free bulk relaxor ferroelectric ceramics by a traditional die-pressing processing route. The uniformity of the grain sizes for these ceramics was improved, and the grains were refined when a certain amount of ZnO was introduced into BaTiO 3 -based ceramics. In addition, the breakdown strength was improved in the case where the relaxor behavior was not significantly improved. It should be noted that the sample doped with 0.02 mol Zn showed the maximum room-temperature storage density (1.51 J/cm3) at the largest electric field strength (210 kV/cm). At the same time, this ceramic exhibited good stability to temperature (60–150 °C) and frequency (10–100 Hz) variations, as well as fantastic fatigue resistance (10,000 charge-discharge cycles). This paper presents in-depth studies of the structure, morphology, electrical properties, and energy storage performance of ZnO-modified BaTiO 3 -based ceramics. [ABSTRACT FROM AUTHOR]

In this paper, the structural, microstructural, dielectric, ferroelectric and magnetic properties of vanadium-doped Barium Calcium Titanate (BCT) ceramics have been reported. All the ceramic samples were prepared by the conventionalsolid-state reaction method. By Rietveld refinement of X-Ray diffraction patterns, we confirm the pervoskite structure of all the prepared samples. A decrease has been observed in lattice parameters (a and c) and lattice volume on the substitution of Ti4+ ions by vanadium ions in BCT lattice. SEM micrographs revealed change in microstructure from irregular, large grain porous structure to a regular small and compact structure. The dielectric constant data above T c has been fitted with both Curie-Weiss Law and Power Law. The dielectric behavior of the presently studied system is more accurately explained by Power law. Feeble ferromagnetism has also been observed with vanadium substitution in BCT ceramics. [ABSTRACT FROM AUTHOR]

The paper presents the results of a study of structural, optical and conductive properties of ferroelectric microparticles based on ATiO x (A = Ba, Ca, Sr) obtained by solid-phase synthesis. According to the data obtained, as a result of the synthesis microparticles of dendroid form were obtained. During the study, the dependences of the change in the phase composition and crystallographic characteristics on the choice of component A in the structure of a ferroelectric are established. Studies of conductive and optical characteristics of investigated microparticles were conducted. During tests of conductive characteristics of microparticles, the nonlinearity of the current – voltage characteristics was established due to the presence of impurity inclusions in the structure and a high concentration of vacancy and dislocation defects, which have a significant effect on the ballistic nature of charge transfer. [ABSTRACT FROM AUTHOR]

Abstract In this paper, we report the influence of Ni doping on the structural, electrical, magnetic and magnetoelectric properties of BaTiO 3 (BTO) ceramics. X-ray diffraction (XRD) analysis indicates a phase transition from tetragonal to hexagonal at x = 2.5 mol%. Further, XRD data has been refined using Rietveld method to extract the phase formation, lattice parameters, and the phase fraction of BaTi 1-x Ni x O 3 (BTNO) (0 ≤ x ≤ 10 mol %) ceramics. The ferroelectric polarization decreases with Ni doping concentration. The relative permittivity of BTNO compositions decreases while the corresponding dielectric loss increases with Ni doping concentration. Room temperature magnetic hysteresis (M-H) loop of all BTNO samples exhibit ferromagnetic nature with a saturated loop except for x = 2.5 mol% Ni doping concentration. At x = 2.5 mol% Ni doping concentration, a small amount of diamagnetism is observed at higher fields along with ferromagnetism. The origin of ferromagnetism is due to the F- center exchange interaction via oxygen vacancies. The highest remnant magnetization (M r) is 11.76 memu/g for x = 10 mol%. The Magnetodielectric coefficient (MD) and magnetoelectric coefficient (ME) gradually increases with increasing Ni doping concentration, and are 1.72% and 4.51 mV cm − 1 Oe − 1 respectively for x = 10 mol%. [ABSTRACT FROM AUTHOR]

Abstract It is challenging to achieve high energy density in conductive fillers/polymer nanocomposites due to their extremely low breakdown strength. In this paper, a novel multi-component and multilayer-structured nanocomposite was designed and investigated, consisting of Ba 0.8 Sr 0.2 TiO 3 decorated graphene (BST @ RGO)/poly(vinylidene fluoride-chlorotrifluoroethylene) copolymer (P(VDF-CTFE)) composites (R-Layer) as interlayer, and BaTiO 3 /P(VDF-CTFE) composites (B-Layer) as surface layer. The multilayer-structured nanocomposites were prepared through layer-by-layer solution casting method. Enhanced breakdown strength, energy density, dielectric constant and low dielectric loss were simultaneously obtained in the nanocomposites by the multilayer structure. The maximum dielectric constant of the composites with multi-layered structure was approximately 14, which was increased by 16.67% compared to the pure P(VDF-CTFE) layer, and the dielectric loss was as low as 0.047 at 1 kHz, even lower than pure P(VDF-CTFE) in frequency range from 10 kHz to 1 MHz. The breakdown strength and energy storage density of BRB-3 nanocomposites with 3 R-Layers reached to 220 kV mm−1 and 6.49 J cm−3, respectively. These results demonstrated that designing multi-component and multilayer-structured nanocomposites was an effective approach to fabricate high performance dielectric nanocomposites. [ABSTRACT FROM AUTHOR]

Electromagnetic radiation (EMR) responses from cement–BaTiO 3 (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 V 2 –sec/sec to 0.00047 V 2 –sec/sec, 0.000065 V 2 – sec/sec to 0.000214 V 2 – sec/sec and 0.000032 V 2 – sec/sec to 0.000135 V 2 – 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. [ABSTRACT FROM AUTHOR]

The electrocaloric effect (ECE) in the ferroelectric ceramics is determined by both the composition and the microstructure. This paper demonstrated the influences of the microstructure features on the ECE in BaTiO 3 ceramics. When the sintering temperature rises, the particles are fused together, the grain size is enlarged and the pore amount decreases, so the ECE ΔT max increases significantly. If the sintering temperature further rises to 1300 °C, the intergranular pores transform to intragranular, so the ΔT peak is enhanced but the value other than the peak is reduced. The ΔT max lowers slightly since the amount of intragranular pores gradually reduces after a second sintering for long time. The clarification of the influences of the microstructure features is instructive for the ECE material design for practical applications. [ABSTRACT FROM AUTHOR]

In the present paper, the effect of addition of a small amount (8 wt%) of barium titanate (BT) on electrical properties of bismuth sodium titanate (BNT) forming a solid solution of a composition (0.92)(Bi 0.5 Na 0.5 TiO 3 )+(0.08)(BaTiO 3 ) (BNT-BT-8) has mainly been reported. The solid solution of BNT-BT-8 was prepared by a cost effective and standard mixed-oxide method. Preliminary structural analysis using X-rays diffraction pattern and data showed the existence of two phases; orthorhombic (major) and tetragonal (minor impurity/secondary) phase. Analysis of scanning electron micrograph and energy dispersive spectrum of the pellet sample reveals the formation of high density with homogeneously distributed grains of varying dimension. The locations, phonon modes statistics, width and intensity of peaks of Raman spectra of BNT-BT-8 was analyzed by Raman spectroscopy and provided some data on molecular structure of the material. The effect of temperature and frequency on some ferroelectric characteristics of the material were studied. The frequency-temperature dependence of electrical characteristical such as impedance of the material was studied by impedance spectroscopy. The electric conductivity follows the Arrhenius equation and provided activation energy at different frequency. The dielectric and impedance spectroscopy suggest the existence of a non-Debye relaxation mechanism in the material. [ABSTRACT FROM AUTHOR]

In this paper, a core-shell structure, where the BaTiO 3 (BT) particles were coated with 0.25Bi(Zn 1/2 Ti 1/2 )O 3 -0.75BaTiO 3 [BT@x(0.25BZT-0.75BT)] by sol-gel method, was fabricated and confirmed by transmission electron microscopy (TEM). The impedance data of BT, 0.25BZT-0.75BT and BT@x(0.25BZT-0.75BT) (x=0.5–1.0) ceramics was collected and fitted by different equivalent circuits. The core and shell regions of BT@x(0.25BZT-0.75BT) (x=0.5–1.0) ceramics can be separated in complex impedance plots (fitted by a 4RC equivalent circuit), according to the activation energies of BT and 0.25BZT-0.75BT. The calculated activation energy of the core part in BT@x(0.25BZT-0.75BT) ceramics is relatively stable, being closer to the activation energy (0.86 eV) of BT, while the activation energy of the shell was found to increase from 0.28 eV to 0.53 eV with increasing the shell thickness. The average core/shell ratio (d gc /d gs ) for BT@0.8(0.25BZT-0.75BT) ceramics was found to be on the order of 7.26, calculated by a modified two-layer dielectric model. In addition, Lichtenecker formula was used to simulate the dielectric constant of BT@0.8(0.25BZT-0.75BT) ceramics at room temperature and the simulated results are in agreement with the measured values. [ABSTRACT FROM AUTHOR]

This paper is concerned with the microstructure of adhesive joints composed of BaTiO 3 ceramic material and two kinds of adhesives, with a special emphasis on the numerical modelling of grain size, shape and material porosity. BaTiO 3 powder for use in stacked-disk multilayer actuator production is manufactured using the solid-state technique. The properties of BaTiO 3 material at each stage of its fabrication that influence its application for the stacked-disk multilayer actuator are presented and discussed. The parameters characterising the properties of the fabricated pellets are also described. Implicit time-discretisation and consistent tangent operators are employed. A 3D microstructure model of BaTiO 3 using Digimat-FE software is generated. Then, effective elastic constants of BaTiO 3 and epoxy adhesive composites are calculated by numerical simulation. The Mori-Tanaka homogenisation scheme for representative volume elements of BaTiO 3 and epoxy adhesives composites is carried out using Digimat-MF software in order to obtain failure characteristics of the composite material. [ABSTRACT FROM AUTHOR]

In this paper, barium titanate nanopowders were obtained by combination of sol–gel and hydrothermal methods, starting from tetrabutyltitanate and barium acetate. Our work was focused on low-temperature synthesis route, as well as structural and morphological characterization of the resulted nanopowders. Moreover, the structure type of barium titanate and magnetic behavior were established. [ABSTRACT FROM AUTHOR]

Previously published results on electrical and mechanical properties of BaTiO 3 coatings prepared by atmospheric plasma spraying showed anomalies in their dielectric response. This paper provides a study of electrical and mechanical properties of BaTiO 3 coatings after thermal posttreatment. The spraying was carried out by a direct current gas-stabilized plasma gun. BaTiO 3 was fed into the plasma jet as a feedstock powder prepared by reactive sintering of micrometer-sized powders of BaCO 3 and TiO 2 . In the next step the coatings were annealed in air. Microstructure and phase composition are reported and discussed in relation to electric and mechanical properties. Dielectric properties are reported for the radio frequency (RF) range. [ABSTRACT FROM AUTHOR]

Fabrication of barium titanate (BaTiO 3 ) specimens was accomplished with binder jetting additive manufacturing, and build parameters (e.g., binder saturation and layer thickness) and sintering profiles were modified to optimize the density achieved and the crystal structures obtained in the 3D printed parts. Surface and cross sectional grain morphology was characterized by scanning electron microscopy (SEM) revealing grain growth on localized areas of BTO fabricated specimens after sintering. Crystal structure was analyzed by X-ray diffraction (XRD) where the presence of a hexagonal phase was observed for BaTiO 3 only when sintered at 1400 °C. The dielectric constant of the fabricated BaTiO 3 specimens sintered at 1260 °C was obtained by using a K u -band wave-guide and vector network analyzer setup in which the relative permittivity was measured from 8.6 to 6.23 for a frequency range of 12.4–18 GHz, respectively. When sintered at 1400 °C for 4 h, a density of 3.93 g/cm 3 was obtained, which corresponds to 65.2% of the theoretical density. Piezoelectric properties exhibited a d 33 value of 74.1 for specimens also sintered at 1400 °C. Results reported in this paper demonstrate the feasibility of BTO as a binder jetting material for 3D printed dielectric structures, ceramic capacitors and gas and pressure sensors. [ABSTRACT FROM AUTHOR]

A new approach, based on fractal geometry and correlation between microstructure–nanostructure and rare-earth properties and other additives doped BaTiO 3 -ceramics and electronics properties, is applied. The grain contacts geometry based on different stereological models and especially intergranular contact surface fractal morphology was the subject of several papers of these authors. The main conclusion was that intergranular capacities have higher values then expected which is induced by contact surfaces sizes augmentation as a consequence of their fractal nature. Bigger micro-capacities were justified by virtually having bigger dielectric constants which was achieved by introducing fractal correction factor α 0 >1, as a multiplier to the usual dielectric constant ε r to gain a bigger value of α 0 ε r . In further BaTiO 3 -ceramics micro-electronics fractal theory development, different fractal methods were used to describe complexity of the spatial distribution of BaTiO 3 -grains, as well as pores. This led to a fractal correction factor revisited model, which considers existence of surfaces fractality, pores fractality and the inner liquid dynamics and solid state sintering phase within ceramics material represented by the Brownian motion model. The new correction factor α is a function of these three ceramics fractality “sources”. Here, the relationship between α and α 0 is established for doped BaTiO 3 -ceramics using the Curie–Weiss law and temperature as an omnipresent sintering parameter. Also, the model of two grains contact impedance is studied for different α and frequency values. Ву the control of shapes and contact surfaces numbers on the entire BaTiO 3 -ceramic sample level, the control over structural properties of these ceramics can be achieved, with the aim of correlation between material electronic properties and corresponding microstructure. The fractal nature for analysis of the ceramics structure provides a new approach for modeling and prognosis of the grain shape and relations between the BaTiO 3 -ceramic structure, micro- and nano-, and all other electronic properties in the light of new frontier for higher level electronic circuits integration. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a comparison of properties of BaTiO3 ceramics prepared by two different production methods: gas-stabilized plasma spraying (GSP) and spark plasma sintering (SPS). Samples of both materials were evaluated by various techniques, the goal being to detect the Curie temperature of the ferroelectric transformation between the tetragonal and the cubic phase. All tests, resonant ultrasound spectroscopy, dielectric measurements, differential scanning calorimetry and temperature-resolved X-ray diffraction (XRD), used in combination, proved the absence of this transformation in the case of GSP coating up to 500°C. Similarly, the tetragonal-to-orthorhombic transition temperature is shifted downwards, this transition probably taking place in a small fraction of the volume of coating. The SPS samples exhibit several anomalies, such as a strong anisotropy of relative permittivity, but their phase transformations were detected in the usual temperature ranges. [Copyright &y& Elsevier]

Abstract: Ceramic capacitors are an indispensable component in electronic circuits, since they are used in various applications such as timing, filtering, and decoupling. These capacitors are doped with REEs that improve their operating life and electrical properties. In this paper, the economics of rare earth elements (REEs) are reviewed in light of their importance in ceramic capacitors. The developing rare earth element supply and demand crisis that can negatively impact the ceramic capacitor industry and, hence, the global economy, is explained. The cause of this crisis and the response of the world are also discussed. [Copyright &y& Elsevier]

Abstract: The structure of BaTiO3 based materials can be controlled by using different technological parameters and different additives. In this paper, microstructure and dielectrical properties of Er2O3 doped BaTiO3-ceramics, sintered from 1320°C to 1380°C have been investigated. Microstructural investigations were carried out using scanning electron microscope equipped with energy dispersive spectrometer. Grain size distribution was determined by quantitative metallography method. The new correlation between microstructure and dielectric properties of doped BaTiO3-ceramics, based on fractal geometry and contact surface probability, has been developed. Using the fractals and statistics of the grains contact surface, a reconstruction of microstructure configurations, as grains shapes or intergranular contacts, has been successfully done. Obtained results indicated that fractal analysis and statistics model for contact surfaces of different shapes were very important for the prognosis of BaTiO3-ceramics microstructure and dielectric properties. The morphology of ceramics grains pointed out the validity of developing new structure analytical methods, based on different grains’ shape geometries. The grains contact model based on ellipsoidal geometry is presented as new modeling tool for structure research of BaTiO3-ceramics materials. The directions of possible materials properties prognosis are determined according to the correlations synthesis–structure–property.The statistical approach to the investigation of BaTiO3-ceramic grains concerning the relationship between the temperature and the area of the contact surface is also introduced. [Copyright &y& Elsevier]

Abstract: Non-lead barium zirconate titanate (BZT)-Portland cement (PC) composites have been seen as promising new non-lead composites. This paper reports research work on the dielectric and piezoelectric properties of 1–3 non-lead barium zirconate titanate (BZT)-Portland cement (PC) composites. The 1–3 non-lead composites with different BZT contents at 40–70% by volume were fabricated by the dice-and-fill method. The results show that the dielectric loss of the 1–3 non-lead composite was lowest at 0.08 at 70% BZT composites. The models are applied for the calculation with the dielectric constant, piezoelectric coefficient and piezoelectric voltage constant and the results were found to fit closest to that of the parallel model. At 70% BZT content or higher, piezoelectric coefficient was found to have values higher than 130pC/N. In addition, the new 1–3 non-lead composites can be tuned to an ideal compatible value that match the requirement of concrete structure. [Copyright &y& Elsevier]

Abstract: In this paper, we investigated the effect of microwave sintering parameters on the development of the microstructure of nano-grained BaTiO3 materials co-doped with Y and Mg species. It is observed that the materials can not only be sintered densely at a lower temperature (1150°C) and a shorter soaking time (20min), but also the grain growth can be suppressed by 2.45GHz microwave heating process. However, the grain growth exhibits a unique tendency in some processing conditions such as microwave sintering for longer intervals (≧60min) or at higher temperatures (1200°C). The grain growth behavior after densification was investigated in terms of the phenomenological kinetics, and the activation energy for grain growth using microwave sintering (59.4kJ/mol) is considerably less than that of the conventionally sintered ones (96.0kJ/mol), which indicates that microwave sintering process can accelerate the densification rate of the BaTiO3 materials comparing with the conventional sintering process. [Copyright &y& Elsevier]

Abstract: Development of a low-temperature sintered dielectric material derived from barium titanate for X7R characterized dielectric ceramics application is discussed in this paper. By addition of SiO2–B2O3–Li2O sintering additives to commercial BaTiO3 powder, more than 95% of the theoretical density was obtained at a sintering temperature of 950°C in H2/N2 atmosphere. The influence of the composition and procedures on the microstructures, lattice parameters and properties of ceramics materials were systemically studied. After explaining the reason for lower isolated resistivity (IR) in the previous experiment, several methods are tried out to improve the IR properties, which have reached the application requirement level of 1012 Ωcm. These ceramics sintered between 900°C and 950°C in H2/N2 atmosphere are promising candidates for fabrication of Cu electrode MLCCs. [Copyright &y& Elsevier]

Abstract: This paper investigated dielectric properties of rare earth (Dy, Tb, Eu)-doped barium titanate sintered in pure nitrogen. The substituting concentration of rare earth (Dy, Tb, Eu) was 2.0mol%. The doping behaviors of intermediate rare-earth ions (Dy, Tb, Eu) and their effects on the dielectric property of barium titanate were investigated. Eu3+ ion was substituted in the A-site of the perovskite lattice. Dy3+ and Tb3+ ions substituted partially for Ti4+ site and partially for Ba2+ site. The different rare earth element had a crucial effect on dielectric properties of rare-earth-doped BaTiO3. Among these doped samples, Tb-doped BaTiO3 had the largest dielectric constant (70,000–80,000); the smallest dielectric loss (less than 4%), and good capacitance-temperature coefficient, which satisfies the X7R specification of the Electronic Industries Association Standards (TCC within ±15% from −55°C to 125°C). [Copyright &y& Elsevier]