Enhancement Of Dielectric Constant Research Articles

Exploration of structural and dielectric properties of orthorhombic Ta2O5 nanoplatelets towards the potential optoelectronic devices

The dielectric characteristics of tantalum pentoxide (Ta2O5) nanostructures, synthesized by hydrothermal process, have been investigated in the temperature range of 80 K to 400 K and frequency range of 20 Hz to 2 MHz. X-ray diffraction (XRD) confirms the formation of highly crystalline and orthorhombic phase of the nanostructures sintered at 950 ºC. The electron microscope images reveal that the synthesized nanostructures change their morphology to nanoplatelets upon increasing the sintering temperature. Further, UV–visible absorbance, FTIR and Raman spectra of the synthesized nanostructures were obtained to investigate their optical properties. The experimentally obtained dielectric results indicate that both the dielectric constant (ε) and dielectric loss (D) values increase with increasing operating temperature. Also, the dielectric constant increases to 20 while the dielectric loss decreases to <0.025 at room temperature on increasing the sintering temperature. At 300 K and 1 kHz, the value of ε becomes almost twice that of as-synthesized nanostructures i.e. from 10 to 20 on increasing the sintering temperature to 950 ºC. The enhancement in dielectric constant can be justified by the thermally activated orientational and interfacial polarization associated with the increase in the grain size of the Ta2O5 nanoplatelets at higher sintering temperatures. Furthermore, the frequency dependence of ε indicates the high effect of the distribution of relaxation time in the Ta2O5 nanoplatelets at lower frequencies. Overall, this study provides a better understanding of the structural and dielectric behaviour of Ta2O5 nanostructures in correlation with varying sintering temperature. The results suggest that the orthorhombic Ta2O5 nanoplatelets have potential applications as alternative dielectric materials in various electronic and optoelectronic devices.

Hexagonal Boron Nitride Nanoplatelets Filled Polyphenylene Sulphide Nanocomposites: Influence on Thermal and Dielectric Properties

The Hexagonal Boron Nitride (hBN) nanoplatelets are synthesized using a wet chemical method. X-Ray Diffraction (XRD) shows the hBN nanoplatelets exfoliates along the (002) plane. Transmission Electron Microscope (TEM) observation shows the exfoliated hBN nanoplatelets. The hBN nanoplatelets and polyphenylene suulfiude (PPS) physical mixture are solvent processed using ethyl alcohol. It involves two step processing with the first step of ultrasonic treatment of hBN nanoplatelet in ethyl alcohol followed by mixing it with PPS powder and further sonication. This mixed powder of PPS and hBN nanoplatelets are hot pressed using a compression moulding machine. With more addition of hBN nanoplatelets in PPS matrix shows the enhancement in dielectric constant. In addition, the dispersion of hBN nanoplatelets in the PPS matrix increases the crystallinity and thermal stability.

Ultrafast phase‐field model of frequency‐dependent dielectric behavior in ferroelectrics

AbstractRelaxor ferroelectrics have applications in transducers and capacitors owing to their dielectric relaxation. Although the existence of polar nanoregions (PNRs) inside the relaxor ferroelectrics contributes to enhancing the dielectric response, the dielectric relaxation mechanism remains unclear in the wide frequency range from kHz to THz. In this study, we investigated the frequency‐dependent (103–1012 Hz) dielectric properties using ultrafast phase‐field simulations. The dielectric response is divided into the matrix response, the “collinear” PNR response, and the “non‐collinear” PNR response. Among them, the collinear PNR response accounts for 90% of the dielectric constant enhancement. The response behavior of collinear PNRs has a higher frequency limitation than that of non‐collinear PNRs. The different relaxation times of the collinear PNR lead to a corresponding distinct rotation for the polar vectors. Finally, we investigate the different response behaviors of the polarization in the PNR from the aspect of energy barriers. This study not only promotes the understanding of wide‐range frequency‐dependent dielectric relaxation processes but also guides the design of ultrafast relaxor ferroelectric devices in the future.

Investigation of the structural, magnetic and dielectric properties of NiFe2O4/nanoclay composites synthesized via sol-gel autocombustion

NiFe2O4 nanoparticles supported with 0, 2, 4, and 6 wt% of dodecylalkylammonium intercalated montmorillonite (DDA-MMT) are synthesized by sol-gel autocombustion method. The structural and morphological properties have been analyzed by XRD, FTIR and SEM techniques. The dielectric, magnetic, optical and electrical properties of the prepared samples have been evaluated. XRD analysis confirmed the formation of MMT layers exfoliated NiFe2O4 nanoparticles by showing the absence of 001 reflection of DDA-MMT in NiFe2O4/DDA-MMT compounds. The crystallite size is determined to be 31.32 nm for naked Ni ferrite and decreases with increase of DDA-MMT content, which revealed crystallization of NiFe2O4 is influenced by DDA-MMT. The saturation magnetization of Ni ferrite is found to be increased from 29.84 emu/g to the range of 30.78–38.45 emu/g when supported with DDA-MMT up to 6 wt%. A significant enhancement of dielectric constant, from 2.7 to 4.2, is observed when Ni ferrite is supported with 2 wt% DDA-MMT which could be accounted for interfacial polarization between MMT layers and ferrite nanoparticles. Optical band gap increases from 1.67 to 1.76 eV with application of 2 wt% DDA-MMT as supporting material in Ni ferrite. Present work indicates that the magnetic, dielectric, optical as well as electrical properties of Ni ferrite nanomaterial may be modified by adding the right quantity of DDA-MMT as a supporting material, which will ultimately assist in broadening the uses of Ni ferrite.

Characterization and experimental investigation for gamma–ray shielding competence of basalt-doped polyethylene nanocomposites

Experimental investigations on gamma - rays attenuation parameters and dielectric spectroscopic properties were done on a polymeric mixture with chemical composition (100-x) polyethylene + x basalt, where x = 0, 1, 3, 5, 10, and 20 wt%. Using the melting blending technique,six nanocomposite polymeric samples were prepared. The linear attenuation coefficient μ of each prepared set of samples was measured using a gamma-ray spectrometer including High Purity Germanium detector (HPGe) at energies 662.5, 1173.24, and 1332.51 keV. Based on the measured values of (μ) and sample density, the other effective shielding parameters were calculated. the values of μ showed an increase with increasing the dopant ratios from 0.0 up to 20.0 wt%. In addition, the μ values decreased with the photon's energy. The μ values were found 0.0847 up to 0.1175 cm−1, 0.0571 up to 0.0855 cm−1, and 0.0543 up to 0.075 cm−1 at 662.5, 1173.24, and 1332.51 keV. for B0 up to B20, respectively. The ATR spectroscopy was done on the prepared samples, and a good evidence of adding the filler to the pure polyethylene (HDPE) was obtained. Besides, an enhancement in dielectric constant by insertion of basalt NPs also recorded and can be attributed to the large dielectric constant of basalt compared to pure HDPE.

PEG’s impact as a plasticizer on the PVA polymer’s structural, thermal, mechanical, optical, and dielectric characteristics

An array of water-soluble polymer blends composed of polyvinyl alcohol (PVA) and polyethylene glycol (PEG) have been synthesized by the solution casting technique. The prepared blends were tested using X-ray diffraction (XRD), differential scanning calorimetry, mechanical, optical, and dielectric measurements. According to the XRD studies, PEG has a significant plasticizing impact on PVA, as evidenced by the drop in crystallinity (Xc) values from 31.24 to 25.45%. The thermal study reveals the reduction in the glass transition temperature Tg from 89.2 to 60.6 °C. The outcomes showed that adding PEG affects the mechanical characteristics of PVA/PEG blends, and the ideal blend was one with 25 wt% of PEG loading, where the value of the percentage elongation at break (78%), Toughness (0.44) and surface energy (0.076) reached the highest values at this blend. Meanwhile, Young's modulus declined from 20.34 MPa for pure PVA to 7.07 MPa at 25 wt% PEG. According to the optical studies, the absorption edge shifted from 5.24 to 4.26 eV while the optical band gap ({{E}_{g}}^{ind}, {{E}_{g}}^{d}) decreased from 4.81, 5.46 eV (pure PVA) to 3.77, 5.04 eV (PVA/PEG30%) respectively, which indicates that forming charge transfer complexes between PVA and PEG polymer. The EU values enhanced from 0.238 to 1.296 eV and the refractive index improved from 1.38 to 2.97 when PEG content increased. The dielectric and conduction properties were studied from 100 Hz to 1 MHz. It was demonstrated that the dielectric constant ({varepsilon }{prime}) and dielectric loss ({varepsilon }{prime}{prime}) are highly frequency-dependent. In addition to that, ({varepsilon }{prime}, {varepsilon }{prime}{prime}) values improved from (30, 2) for PVA to (44.46 and 5.39) for PVA/30 wt% PEG blend at 100 Hz, respectively. At the same time, the AC electrical conductivity is improved by increasing the PEG content. These results will likely have far-reaching consequences across a variety of fields, the possible applications due to the increased flexibility of PVA film are flexible packaging, biomedical materials, and other industries that need adaptive and flexible materials. Furthermore, the improved refractive index of the PVA/PEG combination demonstrates its appropriateness for certain applications such as optoelectronic equipment, waveguides, anti-reflective coats, and LEDs. This blend has uses in charge storage devices, such as embedded capacitors due to the enhancement of dielectric constant. Finally, one can say that the research samples have multifunctional applications.

Inducing superior discharged energy density of the nanocomposite films with CsPbBr3 in-situ dispersed in ferroelectric polymer

Polymer-based capacitors are regarded as paramount components in advanced electrical systems due to their intrinsically superior breakdown strength (Eb) and excellent processability. Although the enhancement of dielectric constant (εr) of polymer-based composites has been realized by loading high‐εr inorganic fillers, this approach confronts considerable challenges in filler agglomeration. In this research, CsPbBr3 (CPB) nanoparticles are via in-situ in ferroelectric polymers [P(VDF-HFP)] to form high-quality nanocomposites. εr and Eb of the nanocomposites are concomitant enhancement via introduction of only 0.1 wt.% CPB, leading to an ultrahigh Ud ∼ 24.1 J cm-3 at 705 MV m-1 with superior efficiency (η) of 64 % and stability up to 2.5 × 104 charge-discharge cycles. COMSOL Multiphysics simulations further demonstrate that the in-situ prepared composites are conducive to inhibiting the growth of electronic trees caused by inhomogeneous electric field distribution. This contribution extends the synthesis method to prepare perovskites-polymer dielectrics and provides a novel strategy for fabricating high-performance polymer-based composite capacitors.

Anisotropic reinforcement in polymer nanocomposites using dielectric-magnetic difunctional fibers

One-dimensional (1D) functional fibers have been widely used for the property enhancement of polymer nanocomposites. Modulating the orientations of fibers is crucial to maximizing the performances of the nanocomposites. In this work, we report anisotropic polymer nanocomposites enabled by dielectric-magnetic difunctional ceramic fibers, where the magnetic Fe2O3 nanoparticles (FO nps) were confined inside the dielectric ceramic fibers, to produce concurrent strong magnetism and high dielectric/piezoelectric responses. The difunctional fibers can rotate well along the direction of the external magnetic field during the nanocomposite processing, producing notable anisotropic enhancements of polymer nanocomposites. By computing the difference in magnetic and gravitational potential energy versus the internal thermal energy of the fibers that serve the alignment, we determined the optimal content of magnetic FO nps for producing a desirable alignment of fibers, while maintaining the high insulativity of nanocomposites. Finally, the resultant anisotropic polymer nanocomposites with aligned fibers present a maximum 85% enhancement in dielectric constant (ϵr) and 50% enhancement in piezoelectric coefficient (d33), compared to the nanocomposites with random fibers, while maintaining excellent elastic modulus and transmittance. Our work provides an effective strategy for the development of fiber-reinforced polymer nanocomposites with anisotropy and multi-functionality.

Landau level transition and magnetophonon resonance in a twisted bilayer graphene

We perform resonant Raman spectroscopy on 8° twisted bilayer graphene placed in an out-of-plane magnetic field. The high-quality device has narrow Landau level linewidth of less than 5 meV that enables detection of features from both electronic Raman scattering and magnetophonon resonance involving electronic transitions between the low energy Landau levels. Two magnetophonon resonances are observed, one at 4.6T in the strong coupling regime, and the other at 2.6T in the weak coupling regime. Using the measured Landau level transition energy, we analyze the renormalization of effective band velocity, whose dependence on magnetic field points to a 20% enhancement of dielectric constant due to the presence of an adjacent graphene layer, a quite prominent screening effect from a monolayer of carbon atoms in proximity. Both the Landau level transition electronic Raman and the magnetophonon resonance are gate tunable. Harnessing angular momentum conservation, we demonstrate charge tuning of electron phonon coupling strength for left and right circularly polarized G band phonons separately.

Interfacial origin of dielectric constant enhancement in high-temperature polymer dilute nanocomposites

The origin of dielectric constant enhancement in high-temperature (high glass transition temperature Tg) polymer dilute nanocomposites is investigated via Infrared (IR) Spectroscopy applied through Atomic Force Microscope (AFM) and density functional theory (DFT) calculations. The dielectric constant can be greatly enhanced by trace nanofiller loadings (&amp;lt;0.5 vol. %) in a broad class of high-temperature polymers without affecting or even with a positive influence on breakdown strength and dielectric loss. This avenue provides attractive polymer systems for high-performance polymer-based capacitive energy storage in a wide temperature range. In the dilute nanocomposites, the interface regions between the polymers and trace nanofillers are the key to the observed dielectric constant enhancement. This Letter employs AFM-IR to study chain packing in the interface regions of polyetherimide (PEI) dilute nanocomposites. The experimental results and DFT calculations indicate that flexible linkages, i.e., ether groups in PEI, play a crucial role in inducing heterogeneous morphologies in the interface regions. These results are confirmed by studies of PI(PDMA/ODA) and other dilute polymer nanocomposites in the literature as well as by lack of dielectric constant enhancement in PI(Matrimid® 5218) that does not contain flexible linkages.

Fabric-like Electrospun PVAc-Graphene Nanofiber Webs as Wearable and Degradable Piezocapacitive Sensors.

Flexible piezocapacitive sensors utilizing nanomaterial-polymer composite-based nanofibrous membranes offer an attractive alternative to more traditional piezoelectric and piezoresistive wearable sensors owing to their ultralow powered nature, fast response, low hysteresis, and insensitivity to temperature change. In this work, we propose a facile method of fabricating electrospun graphene-dispersed PVAc nanofibrous membrane-based piezocapacitive sensors for applications in IoT-enabled wearables and human physiological function monitoring. A series of electrical and material characterization experiments were conducted on both the pristine and graphene-dispersed PVAc nanofibers to understand the effect of graphene addition on nanofiber morphology, dielectric response, and pressure sensing performance. Dynamic uniaxial pressure sensing performance evaluation tests were conducted on the pristine and graphene-loaded PVAc nanofibrous membrane-based sensors for understanding the effect of two-dimensional (2D) nanofiller addition on pressure sensing performance. A marked increase in the dielectric constant and pressure sensing performance was observed for graphene-loaded spin coated membrane and nanofiber webs respectively, and subsequently the micro dipole formation model was invoked to explain the nanofiller-induced dielectric constant enhancement. The robustness and reliability of the sensor have been underscored by conducting accelerated lifetime assessment experiments entailing at least 3000 cycles of periodic tactile force loading. A series of tests involving human physiological parameter monitoring were conducted to underscore the applicability of the proposed sensor for IoT-enabled personalized health care, soft robotics, and next-generation prosthetic devices. Finally, the easy degradability of the sensing elements is demonstrated to emphasize their suitability for transient electronics applications.

Dielectric Constant Enhancement and Leakage Current Suppression of Metal–Insulator–Metal Capacitors by Atomic Layer Annealing and the Capping Layer Effect Prepared with a Low Thermal Budget

Dielectric Constant Enhancement and Leakage Current Suppression of Metal–Insulator–Metal Capacitors by Atomic Layer Annealing and the Capping Layer Effect Prepared with a Low Thermal Budget

Single material with multiple interfaces: A key one dimensional barium titanate filler for enhancing energy density in polymer nanocomposite

The increasing demand of energy and its storage devices in consumer electronics requires high energy density capacitors. In this context, we proposed a filler of single material with multiple interfaces to enhance the energy density in polymer nanocomposite film. The core-shell polydopamine (PDA) coated BaTiO3 (BT) incorporated in 1D BT architecture filler was prepared by the electrospinning process. In order to investigate the effect of the interfaces, the poly(vinylidene-chlorotrifluoroethylene) (P(VDF-CTFE)) nanocomposite films of a fixed filler (BT, PDA coated BT and 1D core-shell BT) concentration were prepared. The introduction of a ferroelectric filler induces an electroactive phase in P(VDF-CTFE), leading to dielectric constant enhancement by 135% in nanocomposite film. This enhancement in dielectric constant is due to the increased polarizability of nanocomposite film, which was verified by the finite element analysis of electric field distribution. The ferroelectric (polarization vs electric field) loop measurement indicates that the multi-interfaced ferroelectric filler based nanocomposite film exhibits increased maximum polarization of 14.3 μC/cm2, breakdown strength of 5000 kV/cm and improved energy density of 9.9 J/cm3. It implying that an enormous increment (371%) of energy storage as compared to commercial biaxially orientated polypropylene (2.1 J/cm3).

Mechanism of THz dielectric constant enhancement in multi-component oxide glasses investigated by infrared and THz spectroscopies

Dielectric properties of multi-component silicate oxide glasses are investigated with a focus on high dielectric constant oxyfluorosilicate (OFS) glasses by using the infrared reflection spectroscopy and terahertz (THz) time-domain spectroscopy. On the basis of multiple Lorentz oscillator model, vibrational parameters and most responsible ionic pairs are identified for major modes in OFS glasses. The lowest frequency mode is found to dominate the total THz dielectric strength. Among various glasses, the high frequency (optical) dielectric constant shows a superlinear dependence on the electronic polarizability of oxygens. In contrast, the low frequency (THz) mode contribution to the dielectric constant is enhanced by the ionicity (expressed by the polarization ionicity parameter) and exhibits an even steeper dependence on the electronic polarizability. This feature well explains the mechanism of attaining the highest THz dielectric constant in an OFS glass (e.g. ZNbKLSNd glass). Also, the oxygen ion effective charges bearing the lowest frequency modes of OFS glasses are evaluated and found to behave consistently with the polarization ionicity parameter, confirming the relevance of both of these parameters as good ionicity indicators.

Strain-induced giant enhancement of anisotropic dielectric constant in layered nitrides SrHfN2 and SrZrN2.

The development of information technology puts forward huge demand for electronic materials with high dielectric constants; first-principles calculations and simulations have been demonstrated as an efficient technique for screening and exploring novel dielectric materials. In the present study, first-principles calculations combined with density functional perturbation theory are employed to study the dielectric properties of two newly discovered layered nitrides SrHfN2 and SrZrN2 under strain. By analyzing the evolution of lattice distortion, dielectric constant, Born effective charge, and phonon modes along with the applied strain, we find that the biaxial strain and isotropic strain can effectively modulate the dielectric constant. The two nitrides SrHfN2 and SrZrN2 are dynamically stable up to biaxial tensile strains of 2.1% and 1.8%, and the dielectric constants have been enlarged to about 500 and 2000. Furthermore, the dielectric constant is dramatically enhanced by 15 (9) times to a maximum value of ∼2600 (2700) under an isotropic tensile strain of 1.2% (0.7%) for SrHfN2 (SrZrN2), which is mainly due to the softening of the lowest-frequency infrared-active phonon mode and the increasing octahedral distortion degree. Particularly, the ionic contribution of the dielectric constant shows very remarkable anisotropy and plays a dominant role in the change of the dielectric constant, whose in-plane components exhibit giant enhancement by 18 (10) times for SrHfN2 (SrZrN2). This work not only sheds light on the experimentally observed high dielectric constants of SrHfN2 and SrZrN2, but also provides an effective route to regulate the anisotropic dielectric constants by applied strain, which indicates promising applications in optical and electronic devices.

Low-temperature dielectric and impedance properties of Ba1-xSrxTiO3 and BaTi1-xTaxO3 ceramics

In this work, two series of BaTiO3-based ceramics, Ba1-xSrxTiO3 (x = 0, 0.2, 0.4, 0.6, 0.8) and BaTi1-xTaxO3 (x = 0.03, 0.06, 0.075, 0.09, 0.1), were synthesized by using standard solid-state reaction method at 1350 ?C, and then sintered at 1400 ?C for 10 h in air. Frequency-dependent dielectric and impedance properties were investigated at low temperature range of 100-300K. The changes in dielectric properties of the Ba1-xSrxTiO3 ceramics are believed to originate from the phase transition due to the different A-site Sr2+ doping concentration. The local electron-pinned defect-dipole effect is responsible for the enhancement of dielectric constant observed in the B-site Ta5+ doped BaTi1-xTaxO3 ceramics. The complex impedance analysis was used to discern the temperature and frequency dependence of grains and grain boundaries responses. The results suggest that A- and B-site doped BaTiO3 ceramics can be applied for different dielectric devices at low temperatures.

Dielectric constant enhancement of poly 4-vinylphenol (PVPh) via graphene flakes incorporation through electrospray atomization for energy storage.

We report on the fabrication of hybrid composite poly 4-vinlyphenol (PVPh)/graphene thin film via cost-effective electrospray atomization deposition technique. Thin films fabricated through manipulating deposition technique in two different ways which are blending and layer by layer (LBL). For investigation of PVPh/graphene hybrid composite dielectric behavior in comparison to PVPh; three asymmetric MIS thin film capacitors were fabricated, where dielectric thin films (i) PVPh and (ii & iii) hybrid composite thin films PVPh/graphene (blended and LBL) were sandwiched between electrodes i.e. indium tin oxide (ITO) and p-type semiconductor poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). The dielectric properties of the thin films were characterized for frequencies 1 to 100 kHz while utilizing the MIS thin film capacitors. The capacitance obtained at 1 kHz frequency for PVPh/graphene (LBL) dielectric layer at the voltage range ±10 volts was 8.5 mF cm-2 while for blended PVPh/graphene thin film the capacitance at the voltage range ±3 volts was 0.40 μF cm-2 and for pristine PVPh as dielectric layer the capacitance at voltage range ±1 volts was 1.45 μF cm-2. Similarly, even at higher frequencies up to 100 kHz, the PVPh/graphene (LBL) showed stable behavior. Thus, the composite PVPh/graphene (LBL) thin film has a better dielectric nature compared to the composite PVPh/graphene (blended) thin film, even at higher frequencies with larger operational voltage window. This distinguishing nature of the composite PVP/graphene (LBL) is attributed to increase in dielectric constant due to graphene flakes in between PVPh. For the thin films LBL and blended PVPh/graphene, the calculated dielectric constant at 10 kHz is 6.7 and 0.023 while at 100 kHz it is 2 and 0.0167, respectively.

The Effects of Postdeposition Anneal and Postmetallization Anneal on Electrical Properties of TiN/ZrO2/TiN Capacitors

Metal–insulator–metal (MIM) capacitors based on zirconia (ZrO2) are widely used in dynamic random access memories (DRAMs). As the smaller and smaller feature size in DRAM chips requires higher and higher capacitance density, it is necessary to minimize the equivalent oxide thickness (EOT) of ZrO2, or maximize its dielectric constant ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${k}$ </tex-math></inline-formula> ) while maintaining low leakage currents. Annealing is an effective method to achieve high <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${k}$ </tex-math></inline-formula> -values. In this article, we report the impact of two mainstream annealing methods on the electrical properties of ZrO2-based MIM capacitors. The results showed that the dielectric constant of ZrO2 reached 41.5 after postdeposition anneal (PDA) at 350 °C, while grazing incidence X-ray diffraction (GIXRD) measurements indicated the formation of high- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${k}$ </tex-math></inline-formula> tetragonal phase. In contrast, similar dielectric constant enhancement requires much higher temperature (450 °C) for postmetallization anneal (PMA). When similar high- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${k}$ </tex-math></inline-formula> value was reached, the leakage current density of PDA samples was three orders of magnitude lower than that of PMA ones at 0.8 V. Additionally, lower annealing temperature also decreases the parasitic EOT at the interface, which was formed by the interaction of ZrO2 and TiN electrodes. Overall, we found PDA is more beneficial for achieving a higher dielectric constant (>40), lower leakage currents, and lower EOT at lower temperatures compared with PMA, and potentially more suitable for industrial DRAM fabrication process.

Enhancement of microstructure characteristic and dielectric constant of BaMn0.05Ti0.95O3 ceramics

Barium Titanate or BaTiO3, a ferroelectric material with good dielectric properties, is widely studied. The performance of BT is influenced by synthesis and doping. Here, Barium Titanate has been doped with Manganese via the co-precipitation procedure sintered at 900°C and 1000°C. The purposes of this study were to examine the microstructure and dielectric constant of BaMn0.05Ti0.95O3 with variation sintering temperatures at 900°C and 1000°C. The testing employed X-Ray Diffraction (XRD), Fourier Transform Infrared (FTIR), and Resistance Capacitance Inductance (LCR Meter). The XRD data exposed that the crystal size of the BaMn0.05Ti0.9503 sample enlarged from 48.27 nm to 72.41 nm with increasing sintering temperature. The analysis results using FTIR exhibited the existence of Ba-O and Ti-O bonds which confirmed the perovskite structure of BaTiO3. FTIR data also indicated the presence of C-H atomic bonds, which is the peak of impurities in the carbonate phase. The C-H bond vibration decreased at the higher sintering temperature. The dielectric constant value was obtained from the measurements using an LCR meter. In conclusion, increasing the sintering temperature improved the dielectric constant of BaMn0.05Ti0.95O3 from 119 to 386.

Extremely Reduced Dielectric Constant and Band Gap Enhancement in Few-Layered Tungsten Disulfide Nanosheets.

Highly crystalline few-layered tungsten disulfide (WS2) nanosheets were synthesized via a cost-effective, low-temperature hydrothermal route. X-ray diffraction and HR-TEM analysis confirmed the formation of hexagonal nanosheets with thickness of ∼6-8 nm. Raman analysis and AFM results confirmed the few-layered 2H phase of WS2 nanosheets. The UV-vis study shows absorption peaks at 219 and 271 nm with large band gap value of ∼3.12 eV for WS2 nanosheets. Surprisingly, WS2 nanosheets show a dielectric constant of approximately ε' ≈ 5245, whereas bulk WS2 material exhibits a dielectric constant of 7482373. An almost 1426-fold decrease in the value of dielectric constant for the WS2 nanosheet is observed. Such an extreme reduction in dielectric constant and observance of large band gap in WS2 nanosheet were observed for the first time. The present study reveals the excellent and unusual optical and dielectric properties for their potential application in optoelectronic, dielectric, solar, phosphor, and various nanoelectronic devices.