Papers by Keyword: BaTiO₃

Abstract: In this work, 0.33BaTiO₃-0.67BiFeO₃ multiferroic ceramics doped with x mol% MnO₂ (x= 0.1-1.0) were fabricated by solid-state reaction method, and their microstructure and dielectric property were also investigated. The perovskite phase structure of the solid solutions was confirmed by X-ray diffraction patterns, and the formation of minor impure phase of Bi₂Fe₄O₉ was prevent effectively by Mn-doping. With increasing the Mn-doped concentration, the dielectric constants of Mn-doped 0.33BaTiO₃-0.67BiFeO₃ multiferroic ceramics first increased, and reached a maximum value of 340 (measured @1MHz) at the Mn-doped concentration of 0.60 mol%, and then decreased. On the other hand, the dielectric losses first decreased, and reached the minimum value at the Mn-doped concentration of 0.30 mol%, and then increased along with increasing the Mn-doped concentrations. The ferroelectric domain structures in the Mn-doped 0.33BaTiO₃ - 0.67BiFeO₃ multiferroic ceramics with rhombohedral symmetry were also revealed by TEM image and selected area electron diffraction patterns, and tweed-like domain structures were observed.

Abstract: This paper discussed fabrication of TiO2 and BaTiO3 nanotubes by sol-gel method and used anodic aluminum oxide (AAO) as template. The mechanical properties of TiO2 or BaTiO3 NTs are not great, so a longer tube can crack easily, leading to the peeling off of the NTs film from the Ti substrate. Therefore, we propose to use AAO as a template, followed by deposition of TiO2 and BaTiO3 NT inside AAO to make a working electrode for further electronic devices.

Abstract: Lead-free (Ba1-xCax)(Ti0.96Zr0.02Sn0.02)O3 (BCTZS) (x=0, 0.01, 0.02, 0.03) ceramics were prepared using conventional solid-state reaction technique. The effects of Ca content on the microstructure and electrical properties of the BCTZS ceramics were investigated. High piezoelctric coefficient was obtained for the sample at x=0.02.

Abstract: In recent years, the interest in the application of organic materials in electronic devices (light emitting diodes, field effect transistors, solar cells), has shown a rapid increase. Polymer memory devices (PDMs) is a very recent addition to the organic electronics. The polymer memory devices can be fabricated by depositing a blend (an admixture of organic polymer, small organic molecules and metal or semiconductor nanoparticles) between two metal electrodes. We demonstrate the memory effect in the device with simple structure based on blend of polymer with different materials like ionic compound (NaCl), ferroelectrical nano-particles (BaTiO3) and small organic molecules In 2007 Paul has proposed a model to explain memory effect a switching between two distinctive conductivity states when voltage is applied based on electrical dipole formation in the polymer matrix. Here, we investigate if our memory devices based on different types of materials are fitted with the proposed model.

Abstract: For Barium Titanate Ceramics doped with the trivalent and hexavalent chromium oxides, the influence of Cr valence state on dielectric-temperature stability was investigated with Atomic force microscopy, X-ray diffraction, Raman spectroscopy, and dielectric measurements. The application of the trivalent Cr2O3 dopant can give rise to a temperature-stable X7R specification and a lower dielectric loss (< 0.02) when the sample was prepared at 1240 °C, but the dielectric permittivity is lower (~600); Cr ions exist predominantly as Cr4+ and slightly as Cr3+. Increasing sintering temperature will destroy the core-shell structure of the samples. The application of the hexavalent CrO3 dopant can not produce a temperature-stable X7R ceramic; Cr ions exist as Cr4+ and Cr5+. Cr5+ can not enter the perovskite lattice owing to the valence mismatching.

Abstract: A facile one-pot hydrothermal method has been developed for synthesis of porous and non-porous BaTiO3 ceramics using Ba(OH)2.8H2O, BaCO3 as barium source. In this paper, we research the effect of different barium source on the nanostructure of BaTiO3 ceramics in a solid state reaction, and the results indicated that the two different morphologies of BaTiO3 ceramics can be easily prepared by using these two different barium source. The phase composition and morphology of the as-obtained products were investigated by X-ray diffraction and field emission scanning electron microscopy (SEM).

Abstract: Microstructure control in thin-layer multilayer ceramic capacitors (MLCCs) is one of the nowaday challenges for increasing capacitive volumetric efficiency and high voltage dielectric properties. In this paper, the ultrafine-grained BaTiO3 dielectric ceramics with uniform grain size distribution were prepared by chemical coating approach. The doping effects of rare-earth element (Ho) on the microstructures and dielectric properties of the ceramics were investigated. The addition of Ho in nano BaTiO3-based ceramics was found to improve the temperature coefficient of capacitance (TCC) performance, which could be attributed to a significant reduction in the grain size. Moreover, the effects of two-step sintering (TSS) method on the microstructures and dielectric properties, compared with conventional sintering (CS) method, were also discussed. The dielectric constant of ceramics sintered by the TSS method was higher than that of ceramics prepared by CS method. The results reveal that the adoption of TSS method could control the grain size and suppress the abnormal grain growth more effectively, which improves the TCC characteristics.

Abstract: BaTiO₃/ which has good dielectric properties, they were widely used in ceramic capacitors, thermistors, etc. In this study, BaTiO₃/ ceramics prepared by sol-gel powder, then mixed in the organic polymer polyether imide (PEI) and dispersant (surface active agents) and silane coupling agent (Silane Coupling Agent) of the composite material on flexible substrates, And analysis of its properties and electrical properties. Increase by a ceramic powder, to explore the impact of the substrate. In the physical analysis is used XRD, SEM to measure the intensity of crystalline phase and surface uniformity of the electrical measurement using HP4294 measuring dielectric constant and dielectric loss.

Abstract: Lead-free piezoelectric ceramics, (Ba0.85-xSrxCa0.15)(Zr0.1Ti0.9)O3 (BSCZT, x=0.01-0.07), were prepared via a solid-state reaction route. The dielectric properties, ferroelectric properties, piezoelectric and strain properties of BSCZT ceramics were studied. The phase structure and microstructure were investigated by X-ray diffraction and scanning electron microscope, respectively. Results showed that dense ceramics with pure perovskite phase were obtained. At room temperature, the samples with x=0.03 exhibited excellent properties with large piezoelectric coefficient d33=534pC/N, planar mode electromechanical coupling coefficient kp=47.7%, thickness mode electromechanical coupling coefficient kt= 42% and high strain levels of 0.34%. In addition, the study of electrical properties suggested that the Curie temperature decreased linearly from 92oc to 73oc with the increasing doping content of strontium in BCZT ceramics. The remnant polarizations, piezoelectric coefficient and strain levels were all increased as the Sr content increased and then decreased with further increased Sr doping level, giving the maximum values at the Sr content of 3mol%. These results indicated that the BSCZT system is a promising lead-free material for applications in the future.

Abstract: High density BaTiO₃ ceramics have been prepared by the addition of CuO-Bi₂O₃-B₂O₃ mixed oxide. The results indicate that the sintering temperature of BaTiO₃ bulk can be decreased by about 300°C and high dielectric behavior can be remained. The CuO-Bi₂O₃-B₂O₃ additives can increase the breakdown strength, and leads to an obvious enhancement of the energy density, which is nearly 2 times of pure BaTiO₃.