Papers by Keyword: Dielectric

Abstract: In this paper, a Ba_0.6Sr_0.4Fe_11.50Al_0.50O₁₉/MoS₂ composite with a weight ratio of 1:9 has been successfully created. The Ba_0.6Sr_0.4Fe_11.50Al_0.50O₁₉/MoS₂ was synthesized in HEM for 35 hours before sintered at 1000°C for 5 hours. The Ba_0.6Sr_0.4Fe_11.50Al_0.50O₁₉/MoS₂ composite was characterized using XRD for phase formation, crystal structure, and lattice parameters. Based on the XRD results, the Ba_0.6Sr_0.4Fe_11.50Al_0.50O₁₉/MoS₂ composite has two phases with different crystal structures. SEM characterization for surface morphology and particle size. SEM results show heterogeneous particles, but the particle size is not uniform at 0.2-0.6 µm. Measurements of the dielectric constant and dielectric loss are shown as a function of frequency. VSM is used to characterize samples magnetically. The VSM results show ferromagnetic behaviour in the Ba_0.6Sr_0.4Fe_11.50Al_0.50O₁₉/MoS₂ composite with the value of Mr, Ms, and Hc are about 20 emu/g, 40.769 emu/g, and 4.08 kOe, respectively.

Abstract: The electrical properties measurements have been performed in a homogeneous alignment parallelepiped cell containing 4-methoxy benzylidene- 4-butylaniline (MBBA) liquid crystal doped with 0.02%wt tetrabutylammonium bromide (TBAB). The measurement of the complex permittivity was conducted in the nematic phase, covering a frequency range of 42 Hz to 5 MHz. A new relaxation mode was observed in the low-frequency region, which was not present in pure MBBA. The obtained dielectric dispersion could be fitted using the double Cole–Cole formula to determine the relaxation frequencies. The steady-state current exhibited a nonlinear dependence on the applied voltage, and hysteresis was observed in the transient current-voltage characteristic curve.

Abstract: The existence of graphene-based Polyaniline nanocomposite has been demonstrated to be exceptional host matrices for entrapping nano-sized particles, and its composites are widely used in a variety of applications such as transducers, sensors, electrodes, microwave absorption, and thermoelectric applications. The purpose of this study is to investigate the dielectric properties and humidity sensing response of a Fe doped PANI/Graphene (PAFG) composite synthesized in-situ polymerization using adhathoda vasica plant extract. The FT-IR, XRD, and SEM-EDX techniques were used to characterize the sample. The dielectric measurements were performed at 298K over a wide frequency range 5x10¹ to 5x10⁶ Hz. Humidity response studies were performed at room temperature. Iron nanoparticles distributed homogeneously in the PANI matrix were ascertained from IR spectral data. At room temperature, the dielectric properties of the synthesized DS-4 powder outperform those of the synthesized pristine PANI and Fe nanoparticles, with superior dielectric constant and high dielectric loss. When the synthesized iron decorated composite was exposed between 10% and 97% RH, the electrical resistance decreased, which is attributed to the polarization process affecting electrical conductivity within these materials. The PAFG-40% composite exhibited high sensitivity at low humidity levels ranging from 30% to 70% RH.

Abstract: In this study, we investigated the impact of high-energy milling on the structural and dielectric properties of Pb[Zr_(1-x)Ti_x ]O₃ [PZT] ceramics synthesized using the solid-state reaction process. The sample was milled for 2, 4 & 6 hours using a high-energy ball milling machine. The unit cell structure for all of the samples was observed to be monoclinic, according to x-ray diffraction measurements (space group: C1m1). A significant reduction in crystallite size was observed, from 132 nm to 46 nm after 6 hours of milling. The dielectric study indicated a classical ferroelectric type behaviour for the un-milled sample and diffused phase transition for all milled samples. However dielectric constant dropped from 940 to 487 after 6 hours of milling.

Abstract: An electrical insulator known as a dielectric material is a substance that can be solid, liquid, or gaseous. Having a high specific resistance, a dielectric material is a non-metallic substance. A dielectric function as the perfect capacitor, storing and dissipating electrical energy. Due to the rising need for capacitors, semiconductor devices, Liquid Crystal Displays, electrical transformers, and other products, properties including electric susceptibility, dielectric polarisation, dispersion, relaxation, and tunability have received a great deal of attention. Advanced materials must be developed in order to further enhance their performance. Metal-organic frameworks (MOFs), a class of porous crystalline solids, have shown to be ideal models for synthesising functional materials that may be used to make supercapacitor electrodes. Greater electrical conductivity, a higher charge capacity, and variable electrochemical activity are just a few benefits that bimetallic MOFs and their derivatives have over monometallic MOFs. This study focuses on the usage of MOF-derived bimetallic in dielectric materials, with particular attention paid to understanding the cause of the enhanced performance and covering the most recent advancements in the area with a variety of applications.

Abstract: Conductive and flexible electronics have attracted great demands and attention in the field of stretchable and wearable electronic devices. In this work, polydimethylsiloxane (PDMS) was composited with different drops of graphene solution to produce flexible, conductive and optically transparent PDMS/Graphene composite using the drop-cast method. The dielectric constants of PDMS and PDMS/Graphene composite were measured using Agilent dielectric probe. I-V characterization was used to measure the conductivity of the flexible substrate in flat and bending conditions. The UV-VIS was used to measure the transmittance properties of the substrate. Comparing the electrical properties of the pristine PDMS substrate with graphene composited PDMS substrates, the current shows a slight decrease due to the physical morphology of PDMS/Graphene composite that creates a small hole on the surface. No significant changes can be found between 1 drop, 2 drops, 3 drops and 4 drops of graphene in PDMS solution. For the dielectric measurement, the result of composited PDMS/Graphene sample had shown a lower value of dielectric constant (1.1 F/m) compared to pure PDMS (2.33 F/m). This shows that the existence of graphene in PDMS reduces the dielectric constant of pristine PDMS. The result of UV-VIS shows the samples with 4 drops of graphene having the lowest visible transmittance. The PDMS/Graphene composite can be concluded as a dielectric material with a lower dielectric constant. It has the potential to be used as a conductive substrate for further flexible interconnect materials since it has a unique electrical feature and robust mechanical strength.

Abstract: Metal oxide semiconductor (MOS) capacitor is a trilayer device that comprises of metal, dielectric, and semiconductor layer. The advancement of MOS technology has greatly give huge improvement to MOS devices which lead to scaling down the MOS devices. The reduction of dielectric thickness of conventional dielectric material has coming to an end, therefore as alternative new material with high mobility carrier is suggested to overcome the problem. The objectives of this work are to study the performance of MOS capacitor. Two parameters were varied, first the semiconductor material which is silicon (Si), germanium (Ge) and silicon germanium (SiGe) and second is the dielectric material that is silicon dioxide (SiO₂) and silicon nitride (Si₃N₄). The performance of the MOS capacitor is evaluated based on the capacitance-voltage (C-V) and current-voltage (I-V) characteristics. Silvaco TCAD tool were use as as simulation tool for the method of investigation. Result shown that the performance of the MOS capacitor increased when Ge and SiGe were used as semiconductor material and Si₃N₄ as dielectric layer. It can see that with V_T of 4.15 V for MOS with Ge and 4.28 V for MOS with SiGe. For the C-V properties C_max value for both devices are F and F, respectively. The results show that there is around 100% increment in capacitance value when Ge is used as semiconductor layer but there is no increment or decrement in capacitance value when SiGe is used. Based on the obtained results, Ge is chosen as the best semiconductor material.

Abstract: The magnetite (Fe₃O₄) nanoparticles have been green-synthesized using Moringa Oleifera extract (MO) with variations of 5, 10, 15, and 20 ml. The X-ray diffraction results confirmed that the microstructure of Fe₃O₄ nanoparticles is a cubic inverse spinel structure with an average particle size of 5.0-8.9 nm and lattice parameters in the range of 8.14-8.22 Å. The results of UV-VIS data presented that the absorption edges of Fe₃O₄ MO 5 ml were 193.4 nm and the band gap energy of Fe₃O₄-MO is in the range of 2.62-3.31 eV. Dielectric properties were measured using impedance spectroscopy in the frequency range of 10-900 kHz. The results of measurement were in the form of real dielectric (ε'), imaginary dielectric (ε''), and tangent loss (tan δ). The dielectric constant decreased with increasing frequency due to interfacial polarization. In addition, MO affected the dielectric properties of Fe₃O₄ nanoparticles. The dielectrics of green-synthesized Fe₃O₄ with various MO of 5, 10, 15, and 20 ml at a frequency of 10 kHz are 248.5, 276.9, 289.0, and 308.1, respectively. The results measurement of the dielectric properties showed the optimality of the green synthesized sample with MO concentrations of 10 and 15 ml with values ​​of 276.9 and 289.0 at a frequency of 10 kHz. So, green synthesis Fe₃O₄ magnetite nanoparticles are used for Surface Plasmon Resonance (SPR) and Electromagnetic Interference (EMI) Shielding because these two applications are dependent on frequency and dielectric constant.

Abstract: Strontium Oxide (SrO) nanoparticles have a specific structure, and excellent optical, mechanical, and thermal properties, within direct bandgap semiconductors applications. SrO impact on the optical and electrical properties of newly (PVA-PEG/ SrO) nanocomposite were investigated. The electrical properties were measured at 100 Hz – 6 MHz frequencies. An increase in frequency caused a reduction in the dielectric loss (δ) and dielectric constant (ɛ). ɛ value revealed an improvement with an increased loading ratio of SrO. The optical properties of the (PVA-PEG/SrO) nanocomposite showed a reduction in the energy gap values. In contrast, the absorption, extinction coefficient, absorption coefficient, optical conductivity, refractive index, and dielectric constant (imaginary, real) increased with the increased concentration of SrO NPs.

Abstract: Polymer dispersed liquid crystals are composite functional materials having a variety of application ranging from display to smart window. These materials consist of liquid crystal in which micron size droplets of polymer is dispersed. In the present study the effect of different concentration of polymer 2-ethyl hexyl acrylate on optical and electrical properties of nematic liquid crystal 4-cynophenyl 4-n-hexyl benzoate were investigated by various techniques. The investigation of textures at different temperatures was performed by polarizing optical microscopy for the determination of phase transition temperature. The fabry perot scattering studies using low powered laser beam was used for the confirmation of phase transition temperature. Various textures were found according to the orientation of liquid crystal and polymer. The optical and electrical properties of pure liquid crystal were found to enhance after dispersing polymer. Our investigation suggest that after dispersing polymer into nematic liquid crystal, the material shows more stability, less flicking and sticking of image for display applications.