High Dielectric Constant Barium Research Articles

Silicone composites cured under a high electric field: an electromechanical experimental study

AbstractRecently, dielectric elastomers (DEs) become enviable materials for the applications of electromechanical transducers. However, requirements of enhanced properties like high dielectric constants, low elastic moduli, high stretchability, and minimum viscous and dielectric losses are major challenges for actuator and generator applications. To enhance dielectric properties, particle‐filled DE can be prepared in the presence of an electric field during the curing process, which leads to aligned particles in a regular fashion. In this work, we develop a holistic experimental characterization approach to assess how particle alignments enhance mechanical, electrical and electro‐mechanical properties over the randomly particle filled composites. For that, a commercially available silicone polymer (Ecoflex) is used and filled with high dielectric constant barium titanate fillers. In order to substantiate electromechanical performance enhancements, mechanical, electrical, electro‐mechanical, and morphology experiments are conducted on both types of silicone composites. Dielectric composites prepared under an electric field during curing process outperform in almost all aspects of electromechanical tests. This comprehensive study provides a framework that will guide future dielectric composite preparations and electrical, mechanical, and electromechanical experiments especially for the oriented dipole fillers prepared under an electric field.

BaTiO3 assisted PAN fiber preparation of high performance flexible nanogenerator

Recently, polyacrylonitrile (PAN) fiber films have shown greater advantages over polyvinylidene fluoride (PVDF) in the field of energy harvesting. Adding other substances with high piezoelectric coefficient is worth exploring to further improve the output voltage of PAN. Here, we successfully dispersed high dielectric constant barium titanate in PAN nanofiber films with different dosages using an electrospinning technology. The X-ray diffraction and Fourier transform infrared spectroscopy results indicated that BaTiO3 nanoparticles aid in transforming PAN from a 31-helical conformation to a planar zigzag conformation, thus improving the output voltage of PAN nanofibers significantly and also promoting its mechanical properties. In addition, the human body function monitoring experiment showed a good response current to the rhythm of elbow bending, knee bending, running, and breathing. Besides, when a simple rectifier circuit was applied, the capacitor could be charged to 2 V in less than 2 min and light a commercial LED through repeated tapping.

Dielectric Resonator Antenna on Ba TiO3 embedded with TiO2 Nano composite for Wi-Fi applications

A cylindrical dielectric resonator antenna (DRA) energized using microstrip line for Wi-Fi applications is discussed in this paper. The cylindrical DRA of 14mm diameter and 2mm height are fabricated using titanium dioxide (TiO2) nanoparticle embedded in high dielectric constant barium titanate (BaTiO3) material. It is found that the BaTiO3: TiO2 composite is very effective as a radiator. The fabricated DRA radiates in Wi-Fi frequency of 5.5 GHz with good reflection and radiation performance.

Embedded nonlinear passive components on flexible substrates for microelectronics applications

This paper describes nonlinear dielectric composite passive components on flexible metallic substrates for transient protection of electronic devices, most notably against electrostatic discharge (ESD) and electrical overstress (EOS) conditions. In this case, the passive device comprises a polymer composite that contains nonlinear inorganic fillers, an electric field switchable dielectric ceramic Calcium Copper Titanate (CaCu3Ti4O12, CCT), in a metal insulator metal (MIM) configuration. Compatibility with PCB (printed circuit board) in line processing is demonstrated since the fabrication process described is a relatively low temperature process. Advantageously, the construction of such components are such that they can be embedded within a PCB (printed circuit board), thereby allowing miniaturization of the circuit design and can potentially be adopted in an industrial roll to roll manufacturing process. The dielectric characteristics of the CCT filler polymer composites are compared with well-known high dielectric constant Barium Titanate filler polymer composites for capacitor applications. Theoretical models based on effective medium theory are used to predict the dielectric properties of the CCT epoxy composites as a function of filler loading fractions. Maxwell Garnett model was found to provide the best fit to experimental data.

Low-insertion loss phase shifter for millimeter-wave phased array antennas

This paper proposes a compact, low-loss, and low-cost phase shifter for millimeter-wave/sub-THz applications. The basic idea is to perturb the propagation constant of a high resistivity silicon image guide by high-dielectric constant barium lanthanide tetratitanates (BLT) ceramic loading. Three different BLT ceramic samples have been tested. The measured maximum phase-shift variation reaches 150° at 100 GHz with an average insertion loss of 2.85 dB and an insertion loss variation <0.7 dB for a sample of a 5-mm length. The proposed phase shifter has a bandwidth from 95 to 105 GHz. A low-cost fabrication technology has been developed and used to realize this phase shifter.

Electrical and chemical analysis of zinc oxide interfaces with high dielectric constant barium tantalate and aluminum oxide in metal-insulator-semiconductor structures fabricated at Low temperatures

Zinc oxide (ZnO) was incorporated into metal-insulator-semiconductor (MIS) structures featuring high dielectric constant (high-κ) barium tantalate (BaTa 2 O 6 )or alumina (Al 2 O 3 )as the insulator, and the structures were electrically evaluated for potential applications in transparent thin film transistors. The ZnO films were deposited by radio-frequency magnetron sputtering at 100 °C whereas the dielectric films were deposited by the same method at room temperature. The leakage currents of both the BaTa 2 O 6 and Al 2 O 3 structures were on the order of 10 −7 A/cm 2 . The trap density and trapped charge concentration at the BaTa 2 O 6 /ZnO interface were determined to be 6.18 × 10 11 eV −1 cm −2 and 5.82 × 10 11 cm −2 from conductance–voltage and capacitance–voltage measurements. At the Al 2 O 3 /ZnO interface the trap density and trapped charge were more than an order of magnitude smaller at 1.09 × 10 10 eV −1 cm −2 and 1.04 × 10 10 cm −2 respectively. The BaTa 2 O 6 structures had significantly larger frequency dispersions due to the larger number of interface traps. Chemical analysis using X-ray photoelectron spectroscopy with depth profiling indicates that acceptor type defects associated with a deficiency of oxygen are related to the observed electron trapping in the BaTa 2 O 6 MIS structure. Overall, the results indicate that Al 2 O 3 would be better suited for transparent thin film transistors deposited at low temperature or without substrate heating.

High Dielectric Ceramic Nano Particle and Polymer Composites for Embedded Capacitor

Polymer-ceramic nanocomposites based on new concepts were developed for embedded capacitor applications. The dielectric constant was above 80 at 1 MHz and the specific capacitance was successfully achieved 8 nF/cm2. By use of this nanocomposites, multilayer printed wiring boards with embedded passive components were fabricated for prototypes. High dielectric constant Barium titanate (BaTiO3) beads surface modification based on a new concept was applied to improve the affinity between BaTiO3 particles and polymer matrix. Next, the blend polymer of an aromatic polyamide (PA) and an aromatic bismaleimide (BMI) was employed as the matrix as from a view-point of both the processabilty during fabricating the substrates with embedded passive components and the thermal stability during assembling LSI chips. Finally, these technologies were combined and optimized for embedded capacitor materials.

Elaboration of perovskite by decomposition of coprecipitated oxalates for electronic ceramics

Abstract • The present work is an application of the chemistry of coprecipitation oxalates. • The process developed by Lucien and Paul EYRAUD in the “Genie Electrique et Ferroelectricite'’ Laboratory is basis of the decomposition of the coprecipitated oxalates. • The manufacturing of different powders of fine piezoceramics is possible like: BaTiO3 PbTiO3 SrTiO3 PbZr1 -x Ti x O3 PbNb2O6 and so on. I. BaTiO3 The manufacturing of a high dielectric constant barium titanate is obtained by decomposition of a tetrahydrated barium titanyl oxalate. The aim of the study is to obtain a component with dielectric constant higher than 4000 where the relative variation between - 55°C and + 125°C does not exceed ±15%.