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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,621 records · Page 90
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

Growth, characterization and electrochemical properties of hierarchical CuO nanostructures for supercapacitor applications

Graphical abstract: - Highlights: • Hierarchical CuO nanostructures were grown on Cu foil. • Monoclinic phase of CuO was grown. • XPS analysis revealed the presence of Cu(2p{sub 3/2}) and Cu(2p{sub 1/2}) on the surfaces. • Specific capacitance of 94 F/g was achieved for the CuO using cyclic voltammetry. • Impedance spectra show their pseudo capacitor applications. - Abstract: In this paper, we have investigated the electrochemical properties of hierarchical CuO nanostructures for pseudo-supercapacitor device applications. Moreover, the CuO nanostructures were formed on Cu substrate by in situ crystallization process. The as-grown CuO nanostructures were characterized using X-ray diffraction (XRD), Fourier transform-infra red spectroscopy (FT-IR), X-ray photoelectron spectroscopy and field emission-scanning electron microscope (FE-SEM) analysis. The XRD and FT-IR analysis confirm the formation of monoclinic CuO nanostructures. FE-SEM analysis shows the formation of leave like hierarchical structures of CuO with high uniformity and controlled density. The electrochemical analysis such as cyclic voltammetry and electrochemical impedance spectroscopy studies confirms the pseudo-capacitive behavior of the CuO nanostructures. Our experimental results suggest that CuO nanostructures will create promising applications of CuO toward pseudo-supercapacitors.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Dielectric and electrical studies of Pr{sup 3+} doped nano CaSiO{sub 3} perovskite ceramics

Highlights: • CaSiO{sub 3}:Pr{sup 3+} was prepared by facile low temperature solution combustion method. • The crystalline phase of the product is obtained by adopting sintering method. • Samples prepared at 500 °C and calcined at 900 °C for 3 h showed β-phase. • The Pr{sup 3+} doped CaSiO{sub 3} shows “unusual results”. • The electrical microstructure has been accepted to be of internal barrier layer capacitor. - Abstract: CaSiO{sub 3} nano-ceramic powder doped with Pr{sup 3+} has been prepared by solution combustion method. The powder Ca{sub 0.95}Pr{sub 0.05}SiO{sub 3} is investigated for its dielectric and electrical properties at room temperature to study the effect of doping. The sample is characterized by X-ray diffraction and infrared spectroscopy. The size of either of volume elements of CaSiO{sub 3}:Pr{sup 3+} estimated from transmission electron microscopy is about 180–200 nm. The sample shows colossal dielectric response at room temperature. This colossal dielectric behaviour follows Debye-type relaxation and can be explained by Maxwell–Wagner (MW) polarization. However, analysis of impedance and electric modulus data using Cole–Cole plot shows that it deviates from ideal Debye behaviour resulting from the distribution of relaxation times. The distribution in the relaxation times may be attributed to existence of electrically heterogeneous grains, insulating grain boundary, and electrode contact regions. Doping, thus, results in substantial modifications in the dielectric and electrical properties of the nano-ceramic CaSiO{sub 3}.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Electrodeposited manganese dioxide nanostructures on electro-etched carbon fibers: High performance materials for supercapacitor applications

Highlights: • We report a facile method for fabrication of MnO{sub 2} nanostructures on electro-etched carbon fiber. • MnO{sub 2}-ECF electrode shows outstanding supercapacitive behavior even at high discharge rates. • Exceptional cycle stability was achieved for MnO{sub 2}-ECF electrode. • The coulombic efficiency of MnO{sub 2}-ECF electrode is nearly 100%. - Abstract: In this article we introduce a facile, low cost and additive/template free method to fabricate high-rate electrochemical capacitors. Manganese oxide nanostructures were electrodeposited on electro-etched carbon fiber substrate by applying a constant anodic current. Nanostructured MnO{sub 2} on electro-etched carbon fiber was characterized by scanning electron microscopy, X-ray diffraction and energy dispersive X-ray analysis. The electrochemical behavior of MnO{sub 2} electro-etched carbon fiber electrode was investigated by electrochemical techniques including cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy. A maximum specific capacitance of 728.5 F g{sup −1} was achieved at a scan rate of 5 mV s{sup −1} for MnO{sub 2} electro-etched carbon fiber electrode. Also, this electrode showed exceptional cycle stability, suggesting that it can be considered as a good candidate for supercapacitor electrodes.

36 MATERIALS SCIENCE↗
DOE OSTI2015

High energy-storage performance of 0.9Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-0.1PbTiO{sub 3} relaxor ferroelectric thin films prepared by RF magnetron sputtering

Highlights: • High-quality PMN-PT 90/10 RFE thin films were prepared by RF magnetron sputtering. • The maximum discharged density of 31.3 J/cm{sup 3} was obtained in the 750-nm-thick film. • PMN-PT RFE films might be a promising material for energy-storage application. - Abstract: 0.9Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-0.1PbTiO{sub 3} (PMN-PT 90/10) relaxor ferroelectric thin films with different thicknesses were deposited on the LaNiO{sub 3}/Si (100) by the radio-frequency (RF) magnetron sputtering technique. The effects of thickness and deposition temperature on the microstructure, dielectric properties and the energy-storage performance of the thin films were investigated in detail. X-ray diffraction spectra indicated that the thin films had crystallized into a pure perovskite phase with a (100)-preferred orientation after annealed at 700 °C. Moreover, all the PMN-PT 90/10 thin films showed the uniform and crack-free surface microstructure. As a result, a larger recoverable energy density of 31.3 J/cm{sup 3} was achieved in the 750-nm-thick film under 2640 kV/cm at room temperature. Thus, PMN-PT 90/10 relaxor thin films are the promising candidate for energy-storage capacitor application.

36 MATERIALS SCIENCE↗
DOE OSTI2018

High thermal stability and excellent dielectric properties of a novel X8R-type CdCu3Ti4O12 ceramics through a sol-gel technique

Highlights: • CdCu{sub 3}Ti{sub 4}O{sub 12} (CdCTO) ceramics were successfully synthesized via the sol-gel method, and the optimized processing parameters were obtained. • The outstanding dielectric properties: ε{sub r} ≈ 1.63 × 10{sup 4} and tan δ = 0.035 (at 10 kHz) could be obtained in CdCTO ceramics sintered at 1000 °C. • The CdCTO-SG ceramics obtained an excellent thermal stability. - Abstract: CdCu{sub 3}Ti{sub 4}O{sub 12} (CdCTO) ceramics were systematically synthesized via the sol-gel technique. The optimal CH{sub 3}COOH and Ti(OC{sub 4}H{sub 9}){sub 4} concentrations in the synthesis solution and processing temperature were found to be 5.0 vol%, 0.50 mol/L and 60 °C, respectively. These materials exhibited high densities and fine-grained microstructures along with outstanding dielectric properties, including an ε{sub r} of approximately 1.63 × 10{sup 4} and a tan δ of 0.035 at 10 kHz. Over the temperature range from −55 to 150 °C, the temperature coefficients of the dielectric constant at 1 and 10 kHz were −13.9% to 1.20% and −9.10% to 3.92%, respectively, indicating that these ceramics possess excellent thermal stability. These properties also meet the requirements for X8R applications. Data acquired from complex impedance spectroscopy and electrical modulus assessments demonstrates that the superior dielectric properties of these CdCTO ceramics can be attributed to the internal barrier layer capacitor theory (IBLC).

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Braunite phase embedded Y2O3/MnO2-Al2O3-CaO-SiO2 glass ceramics and their properties

Highlights: • Nucleation of synthetic braunite structure (Mn{sub 7}SiO{sub 12}) on sintering of Y{sub 2}O{sub 3}/MnO{sub 2}-CaO-Al{sub 2}O{sub 3}-SiO{sub 2} glasses at 850 °C. • Lossy capacitor behaviour. • Exhibits a critical temperature in 500–600 °C range. • Conduction mechanism shift from Superlinear power law to universal dielectric response law with increase in temperature. - Abstract: Glass series (20-x)Y{sub 2}O{sub 3}-xMnO{sub 2}-20Al{sub 2}O{sub 3}-40SiO{sub 2}-20CaO (x = 5, 10, 15 and 20, mol%) have been synthesized by melt quench technique followed by sintering at 850 °C. The optical band gap of the samples is in wide semiconductor range and increased with MnO{sub 2} content. Photoluminescence study exhibits emission in Mn{sup 2+} d-states. On the other hand, hardness decreases with MnO{sub 2} content except for 10 mol% MnO{sub 2} containing glasses (YM10). The formation of braunite phase in glass ceramics induces capacitive losses. In lower temperature region, the conductivity behaviour of samples follows superlinear power law. In higher temperature region, it follows the universal law of conduction. The dielectric constant for the sintered glasses is constant with respect to temperature, approximately upto 350 °C and 1 MHz frequency. Above 350 °C, the ionic conduction dominates in all the sintered glasses. The anomaly in properties is observed when the ratio of Y{sub 2}O{sub 3}/MnO{sub 2} is 1:1.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Single-step hydrothermal synthesis of wrinkled graphene wrapped TiO2 nanotubes for photocatalytic hydrogen production and supercapacitor applications

Highlights: • Wrinkle rGO wrapped TiO{sub 2} nanotubes were prepared by alkanine hydrothermal method. • Improved visible absorption and reduced recombination was witnessed in rGO-TiO{sub 2}. • H{sub 2} production of 24,880 μmole/g/h was achieved by rGO-TiO{sub 2}, 12.9 folds to P25 TiO{sub 2}. • Double layer and pseudo capacitance of rGO-TiO{sub 2} showed specific capacitance 160 F/g. - Abstract: Herein, we discuss the synthesis of reduced graphene oxide and TiO{sub 2} (rGO-TiO{sub 2}) nanocomposites with varying ratios of rGO to TiO{sub 2} by hydrothermal method. Photocatalytic ability of the nanocomposites was assessed for H{sub 2} production under natural sunlight. At 5 wt% GO loading, the rGO-TiO{sub 2} exhibited 24,880 μmol/g/h H{sub 2}, 12.9 times to commercial P25-TiO{sub 2} (1920 μmol/g/h). The symmetric supercapacitor device fabricated using rGO-TiO{sub 2} demonstrated 160 F/g specific capacitance with 99% retention. The efficient charge carrier separation and transportation between TiO{sub 2} nanotubes and rGO resulted high photocatalytic activity. The synergistic double layer pseudo capacitor behavior of rGO-TiO{sub 2} is the reason for improved specific capacitance.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

Polypyrrole nanowires coated with a hollow shell for enhanced electrochemical performance

Highlights: • A hollow shell coated on polypyrrole nanowires is constructed with the assistance of atomic layer deposition (ALD). • Binder-free electrode of holloe core-shell polypyrrole-TiO{sub 2} is obtained • The hollow core-shell nanostructure shows apparent higher capacitance and better cycling stability than the bare nanowires. - Abstract: Conducting polymers are promising electrode materials for electrochemical capacitors, but are suffered from poor cycling stability and relatively low capacitance. Herein, a hollow shell coated on polypyrrole (Ppy) nanowires is designed and constructed with the assistance of atomic layer deposition (ALD). Ppy nanowires are firstly deposited on flexible carbon cloth by electrodeposition, then a thin sacrificial layer of ZnO and a thin shell of TiO{sub 2} are deposited uniformly on the surfaces of the nanowires. After removing the ZnO layer, a nanogap between the Ppy core and TiO{sub 2} shell is formed thus generate a hollow core-shell Ppy-TiO{sub 2} (noted as Ppy·TiO{sub 2}) nanoarray. When tested as supercapacitor electrodes, the hollow core-shell nanostructure shows apparent higher capacitance and better cycling stability than the bare nanowires. Such enhancement is ascribed to the rational hollow structure design that provides enlarged surface areas and enhanced structure stability. Such hollow structure can be extended to other conducting polymers and electrodes for various electrochemical applications.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

Solution-based spin-coated tin sulfide thin films for photovoltaic and supercapacitor applications

Highlights: • Tin sulfide (SnS{sub x}) thin films were prepared by solution-based spin coating. • The SnS{sub x} films annealed at 500 °C exhibited a pure SnS phase. • The films exhibited direct band gap of 1.4 eV which is near to solar maximum. • The films with the pure SnS phase exhibited a specific capacitance of 42 F g{sup ―1}. - Abstract: In this study, tin sulfide (SnS{sub x}) thin films were prepared using a solution-based spin-coating method. The annealing temperature was observed to play a dominant role in determining the phase, crystallinity, and morphology of the SnS{sub x} thin films. The results obtained from X-ray diffraction, as well as optical and electrical measurements, revealed that the films annealed at 500 °C exhibit a pure SnS phase, with a carrier concentration and direct band gap of ∼10{sup 12} and 1.4 eV, respectively. To explore the applications of SnS in supercapacitors, electrochemical measurements were performed in a 0.2 M NaOH solution. The results indicated that films with a pure SnS phase have a high specific capacitance of 42 F g{sup ―1} at a current density of 2 A g{sup ―1}. The synthesized SnS thin films demonstrate potential for applications in electrochemical capacitors and solar cells.

14 SOLAR ENERGY↗
DOE OSTI2026

Near-field passive sensor for the monitoring of high-temperature oxidative corrosion of metals

This study reports on the development and testing of a passive wireless device designed to track temperature and corrosion behavior in SS304H stainless steel under elevated temperatures. The ANSYS HFSS software was utilized to model and optimize the design of an inductor-capacitor (LC) resonator passive wireless sensors fabricated using platinum designs printed onto an aluminum oxide support operating at frequencies between (50–190 MHz). The optimal LC wireless sensor designs were then fabricated using screen-printing and sintering methods. Here, the sensors were tested by placing the sensor onto polished SS304H flat substrates and heated to 900–1050 °C in air. Wireless acquisition of sensor data during heating, cooling, and isothermal stages was achieved through a Pt loop antenna connected to an RF signal generator and a network analyzer.

20 FOSSIL-FUELED POWER PLANTS↗
DOE OSTI2017

Conceptual design of a 15-TW pulsed-power accelerator for high-energy-density—physics experiments

We have developed a conceptual design of a 15-TW pulsed-power accelerator based on the linear-transformer-driver (LTD) architecture described by Stygar [W. A. Stygar et al., Phys. Rev. ST Accel. Beams 18, 110401 (2015)]. The driver will allow multiple, high-energy-density experiments per day in a university environment and, at the same time, will enable both fundamental and integrated experiments that are scalable to larger facilities. In this design, many individual energy storage units (bricks), each composed of two capacitors and one switch, directly drive the target load without additional pulse compression. Ten LTD modules in parallel drive the load. Each module consists of 16 LTD cavities connected in series, where each cavity is powered by 22 bricks connected in parallel. This design stores up to 2.75 MJ and delivers up to 15 TW in 100 ns to the constant-impedance, water-insulated radial transmission lines. The transmission lines in turn deliver a peak current as high as 12.5 MA to the physics load. To maximize its experimental value and flexibility, the accelerator is coupled to a modern, multibeam laser facility (four beams with up to 5 kJ in 10 ns and one beam with up to 2.6 kJ in 100 ps or less) that can provide auxiliary heating of the physics load. The lasers also enable advanced diagnostic techniques such as X-ray Thomson scattering and multiframe and three-dimensional radiography. The coupled accelerator-laser facility will be the first of its kind and be capable of conducting unprecedented high-energy-density–physics experiments.

47 OTHER INSTRUMENTATION↗
DOE OSTI2022

In-plane and through-plane dielectric properties of graphene oxide membrane: Effect of Al 3 + modification

A graphene oxide (GO) membrane can be used in structural dielectric capacitors and planar micro-supercapacitors as a dielectric separator material due to its excellent through-plane and in-plane dielectric properties. The ability to tailor the dielectric properties of the GO membrane is crucial for dielectric applications. We believe this to be the first demonstration describing how Al 3+ ions impact the dielectric properties of the GO membrane through cation to oxygenated functional groups interactions. In this work, the Al 3+ -modification to the GO membrane was realized through a facile pre-coordination method followed by layer-by-layer assembling. The influence of Al 3+ on the GO membranes’ through-plane and in-plane dielectric properties (dielectric constant and dielectric loss) was investigated in the frequency range from 0.01 Hz to 10 5 Hz. Plane-to-plane and edge-to-edge Al 3+ coordination with the functional group on the basal plane or edge of the GO sheets was proposed to understand the metal ion's impact on the dielectric properties. The results demonstrated that the Al 3+ modification was an effective strategy to tailoring the GO membranes’ dielectric properties in a low frequency regime and further suggested the possibility of designing dielectric GO membranes with controllable dielectric performance. At a low frequency range (0.01–1 Hz), the addition of Al 3+ increased the through-plane dielectric constant and decreased the in-plane dielectric constant. In terms of dielectric loss, unmodified GO membranes exhibited a higher in-plane dielectric loss than the through-plane dielectric loss. Al 3+ -modified GO membranes exhibited increased through-plane dielectric loss and decreased in-plane dielectric loss compared to the unmodified GO membranes.

36 MATERIALS SCIENCE↗
DOE OSTI2013

A 15GSa/s, 1.5GHz bandwidth waveform digitizing ASIC

The PSEC4 custom integrated circuit was designed for the recording of fast waveforms for use in large-area time-of-flight detector systems. The ASIC has been fabricated using the IBM-8RF 0.13 micron CMOS process. On each of 6 analog channels, PSEC4 employs a switched capacitor array (SCA) 256 samples deep, a ramp-compare ADC with 10.5 bits of DC dynamic range, and a serial data readout with the capability of region-of-interest windowing to reduce dead time. The sampling rate can be adjusted between 4 and 15 Gigasamples/second [GSa/s] on all channels and is servo-controlled on-chip with a low-jitter delay-locked loop (DLL). The input signals are passively coupled on-chip with a -3 dB analog bandwidth of 1.5 GHz. The power consumption in quiescent sampling mode is less than 50 mW/chip; at a sustained trigger and readout rate of 50 kHz the chip draws 100 mW. After fixed-pattern pedestal subtraction, the uncorrected integral non-linearity is 0.15% over an 750 mV dynamic range. With a linearity correction, a full 1 V signal voltage range is available.The sampling timebase has a fixed-pattern non-linearity with an RMS of 13%, which can be corrected for precision waveform feature extraction and timing.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2019

LAB4D: A low power, multi-GSa/s, transient digitizer with sampling timebase trimming capabilities

The LAB4D is a new application-specific integrated circuit (ASIC) of the Large Analog Bandwidth Recorder and Digitizer with Ordered Readout (LABRADOR) family, for use in direct wideband radio frequency digitization such as is used in ultrahigh energy neutrino and cosmic ray astrophysics. The LAB4D is a single channel switched-capacitor array (SCA) 12-bit sampler with integrated analog-to-digital converters (ADC), developed in the TSMC 0.25um process. The LAB4D, operating at 3.2GSa/s, contains 4096 total samples arranged in 32 windows, for a total record length of 1280ns. The 3dB bandwidth is approximately 1.3GHz, with a directly-coupled 50ohm input. This represents a factor of 16 increase in the sample depth and an increase in analog bandwidth and sampling depth in comparison to the previous generation LAB3 digitizer. Individually addressable windows allow for sampling and digitization to occur simultaneously, leading to nearly deadtime-free readout for kHz readout rates. All biases and current references are generated via internal digital-to-analog converters (DACs), resulting in a stand-alone digitizer with no additional support circuitry. In addition, the LAB4D contains sample cell timebase trimming capabilities, reducing the intrinsic sample-to-sample time variance to less than 5ps; an improvement of about 80%. This allows the LAB4D to be used in precision timing applications with minimal post-hoc calibration.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2019

Front-end electronic readout system for the Belle II imaging Time-Of-Propagation detector

The Time-Of-Propagation detector is a Cherenkov particle identification detector based on quartz radiator bars for the Belle II experiment at the SuperKEKB ee collider. The purpose of the detector is to identify the type of charged hadrons produced in ee collisions, and requires a single photon timing resolution below 100 picoseconds. A novel front-end electronic system was designed, built, and integrated to acquire data from the 8192 microchannel plate photomultiplier tube channels in the detector. Waveform sampling of these analog signals is done by switched-capacitor array application-specific integrated circuits. The processes of triggering, digitization of windows of interest, readout, and data transfer to the Belle II data acquisition system are managed by Xilinx Zynq-7000 programmable system on a chip devices.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2025

Design of an 8-channel 40 GS/s 20 mW/Ch waveform sampling ASIC in 65 nm CMOS

One picosecond timing resolution is the entry point to signature based searches relying on secondary/tertiary vertices and particle identification. We describe PSEC5, an 8-channel 40 GS/s waveform-sampling ASIC in TSMC 65 nm process targetting one picosecond resolution at 20 mW power per channel. Each channel consists of four fast and one slow switched capacitor arrays (SCA), allowing for picosecond time resolution combined with a long effective buffer. Each fast SCA is 1.6 ns long and has a nominal sampling rate of 40 GS/s. The slow SCA is 204.8 ns long and samples at 5 GS/s. Recording of the analog data for each channel is triggered by a fast discriminator capable of multiple triggering during the window of the slow SCA. To achieve a large dynamic range, low leakage, and high bandwidth, the SCA sampling switches are implemented as 2.5 V nMOSFETs controlled by 1.2 V shift registers. Stored analog data are digitized by an external ADC at 10 bits or better. Specifications on operational parameters include a 4 GHz analog bandwidth and a dead time of 20 microseconds, corresponding to a 50 kHz readout rate, determined by the choice of the external ADC. PSEC5 has been submitted for fabrication.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2024

Fast spark-detection system for GEM detectors

The sPHENIX experiment is currently under commissioning at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Lab (BNL). The Time Projection Chamber (TPC) serves as a tracking detector for the experiment. The sPHENIX TPC uses a stack of four Gas Electron Multipliers (GEMs) as a gain stage in a reduced ion back-flow configuration. To mitigate the damaging effects of sparks in the GEMs, an online spark monitoring system was created. Once the system detects a spark in a GEM stack, the voltages across the GEMs in that stack can be lowered to prevent further sparking without affecting the gain and efficiency of the other modules. Spark signals are coupled out of the GEM stack by a pick-off capacitor attached to the bottom of the bottom GEM. Custom PCBs convert the oscillatory spark signal into a mono-polar pulse that is then digitized. The software then saves the waveform in a server and uses experimentally derived thresholds to determine how to react. As a result, the system has so far proven to be effective at improving the stability of the TPC and preventing damaging events while collecting cosmic ray data.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗