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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

BaZn{sub 2}Si{sub 2}O{sub 7} and the solid solution series BaZn{sub 2−x}Co{sub x}Si{sub 2}O{sub 7} (0<x≤2) as high temperature seals for solid oxide fuel cells studied by high-temperature X-ray diffraction and dilatometry

For sealing of solid oxide fuel cells, glasses from which crystalline phases with high coefficient of thermal expansion (CTE) can be crystallized are required. In this paper, a new solid solution series BaZn{sub 2−x}Co{sub x}Si{sub 2}O{sub 7} (0<x≤2) is introduced which exhibit extremely high CTE. The prepared powders were characterized by X-ray diffraction and high-temperature X-ray diffraction (BaZn{sub 2}Si{sub 2}O{sub 7}). Sintered specimens were characterized by dilatometry. The introduction of Co{sup 2+} does not lead to a change in the space group. All compounds show a transition of a low to a high temperature modification. The attributed temperature increases from 300 °C for BaZn{sub 2}Si{sub 2}O{sub 7} to 850 °C for BaCo{sub 2}Si{sub 2}O{sub 7}. The volume expansion which runs parallel to the phase transition decreases with increasing cobalt concentration. The phase BaZn{sub 2}Si{sub 2}O{sub 7} shows the largest CTE and a steep volume effect during phase transition. For the compound BaZn{sub 0.25}Co{sub 1.75}Si{sub 2}O{sub 7} the CTE is minimum (8.6×10{sup −6} K{sup −1} (50–900 °C)) and increases again until for the compound BaCo{sub 2}Si{sub 2}O{sub 7} a CTE of 16.6×10{sup −6} K{sup −1} (50–900 °C) is reached. In the cobalt rich composition range, the CTEs are in the right range for high temperature fuel cells and can be adjusted by the composition. - Graphical abstract: The composition of the solid solution BaZn{sub 2−x}Co{sub x}Si{sub 2}O{sub 7} strongly affects the thermal expansion. Display Omitted - Highlights: • We examined the thermal expansion of solid solutions BaZn{sub 2−x}Co{sub x}Si{sub 2}O{sub 7} (0<x≤2). • BaZn{sub 2}Si{sub 2}O{sub 7} exhibits the highest thermal expansion due to a phase transition. • Substitution of small amounts of Zn{sup 2+} against Co{sup 2+} lead to decreasing thermal expansion. • The thermal expansions re-increased with further increasing Co{sup 2+} concentrations. • Seals based on these solid solutions should be suitable for solid oxide fuel cells.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Solid state synthesis, crystal growth and optical properties of urea and p-chloronitrobenzene solid solution

Urea is an attractive material for frequency conversion of high power lasers to UV (for wavelength down to 190 nm), but its usage is hindered due to its hygroscopic nature, though there is no alternative organic NLO crystal which could be transparent up to 190 nm. The hygroscopic character of urea has been modified by making the solid solution (UCNB) of urea (U) and p-chloronitrobenzene (CNB). The formation of the solid solution of CNB in U is explained on the basis of phase diagram, powder XRD, FTIR, elemental analysis and single crystal XRD studies. The solubility of U, CNB and UCNB in ethanol solution is evaluated at different temperatures. Transparent single crystals of UCNB are grown from its saturated solution in ethanol. Optical properties e.g., second harmonic generation (SHG), refractive index and the band gap for UCNB crystal were measured and their values were compared with the parent compounds. Besides modification in hygroscopic nature, UCNB has also shown the higher SHG signal and mechanical hardness in comparison to urea crystal. - Highlights: • The hygroscopic character of urea was modified by making the solid solution • Solid solution formation is support by elemental, powder- and single crystal XRD • Crystal of solid solution has higher SHG signal and mechanical stability. • Refractive index and band gap of solid solution crystal have determined.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Nanoscale Solid State Batteries Enabled by Thermal Atomic Layer Deposition of a Lithium Polyphosphazene Solid State Electrolyte

Several active areas of research in novel energy storage technologies, including three-dimensional solid state batteries and passivation coatings for reactive battery electrode components, require conformal solid state electrolytes. We describe an atomic layer deposition (ALD) process for a member of the lithium phosphorus oxynitride (LiPON) family, which is employed as a thin film lithium-conducting solid electrolyte. The reaction between lithium tert-butoxide (LiO t Bu) and diethyl phosphoramidate (DEPA) produces conformal, ionically conductive thin films with a stoichiometry close to Li 2 PO 2 N between 250 and 300°C. The P/N ratio of the films is always 1, indicative of a particular polymorph of LiPON which closely resembles a polyphosphazene. Films grown at 300°C have an ionic conductivity of (6.51 ± 0.36)×10 -7 S/cm at 35°C, and are functionally electrochemically stable in the window from 0 to 5.3V vs. Li/Li + . We demonstrate the viability of the ALD-grown electrolyte by integrating it into full solid state batteries, including thin film devices using LiCoO 2 as the cathode and Si as the anode operating at up to 1 mA/cm 2 . The high quality of the ALD growth process allows pinhole-free deposition even on rough crystalline surfaces, and we demonstrate the fabrication and operation of thin film batteries with the thinnest (<40nm) solid state electrolytes yet reported. Finally, we show an additional application of the moderate-temperature ALD process by demonstrating a flexible solid state battery fabricated on a polymer substrate.

25 ENERGY STORAGE↗
DOE OSTI2015

Exploring hardness enhancement in superhard tungsten tetraboride-based solid solutions using radial X-ray diffraction

In this paper, we explore the hardening mechanisms in WB4-based solid solutions upon addition of Ta, Mn, and Cr using in situ radial X-ray diffraction techniques under nonhydrostatic pressure. By examining the lattice-supported differential strain, we provide insights into the mechanism for hardness increase in binary solid solutions at low dopant concentrations. Speculations on the combined effects of electronic structure and atomic size in ternary WB 4 solid solutions containing Ta with Mn or Cr are also included to understand the extremely high hardness of these materials.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Enhanced ionic conductivity with Li 7 O 2 Br 3 phase in Li 3 OBr anti-perovskite solid electrolyte

Cubic anti-perovskites with general formula Li 3 OX (X = Cl, Br, I) were recently reported as superionic conductors with the potential for use as solid electrolytes in all-solid-state lithium ion batteries. These electrolytes are nonflammable, low-cost, and suitable for thermoplastic processing. However, the primary obstacle of its practical implementation is the relatively low ionic conductivity at room temperature. In this work, we synthesized a composite material consisting of two anti-perovskite phases, namely, cubic Li 3 OBr and layered Li 7 O 2 Br 3 , by solid state reaction routes. The results indicate that with the phase fraction of Li 7 O 2 Br 3 increasing to 44 wt. %, the ionic conductivity increased by more than one order of magnitude compared with pure phase Li 3 OBr. Formation energy calculations revealed the meta-stable nature of Li 7 O 2 Br 3 , which supports the great difficulty in producing phase-pure Li 7 O 2 Br 3 at ambient pressure. Here, methods of obtaining phase-pure Li 7 O 2 Br 3 will continue to be explored, including both high pressure and metathesis techniques.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

Solid-Solution CrCoCuFeNi High-Entropy Alloy Thin Films Synthesized by Sputter Deposition

The concept of high configurationally entropy requires that the high-entropy alloys (HEAs) yield single-phase solid solutions. However, phase separations are quite common in bulk HEAs. A five-element alloy, CrCoCuFeNi, was deposited via radio frequency magnetron sputtering and confirmed to be a single-phase solid solution through the high-energy synchrotron X-ray diffraction, energy-dispersive spectroscopy, wavelength-dispersive spectroscopy, and transmission election microscopy. The formation of the solid-solution phase is presumed to be due to the high cooling rate of the sputter-deposition process.

Microstructure↗
DOE OSTI2022

Operation and Control of Soft Switching Solid State Transformer as a Virtual Synchronous Machine for Photovoltaic Application

Possibility for control and operation of a three-phase solid state soft switching transformer based as a virtual synchronous machine or synchronverter has been investigated in this paper. The soft switching solid state transformer is used as an interface between the ac grid and a photovoltaic power generation unit supported by a battery bank. The control architecture investigated in this paper is that of a synchronverter to achieve inertial support to the grid and local loads. The operation of the soft switching solid state transformer has also been investigated as a V S M during unbalanced/distorted grid voltage condition. Control objective to achieve oscillation free power transfer between the ports (photovoltaic, battery and grid) has been achieved. The presented architecture has been verified for several important case studies via numerical simulations based on MATLAB/Simulink domain.

grid current controller↗
DOE OSTI2016

Complete doping in solid-state by silica-supported perchloric acid as dopant solid acid: Synthesis and characterization of the novel chiral composite of poly [(±)-2-(sec-butyl) aniline]

Poly [(±)-2-(sec-butyl) aniline]/silica-supported perchloric acid composites were synthesized by combination of poly[(±)-2-sec-butylaniline] base (PSBA) and the silica-supported perchloric acid (SSPA) as dopant solid acid in solid-state. The X-ray photoelectron spectroscopy (XPS) and CHNS results confirm nigraniline oxidation state and complete doping for composites (about 75%) and non-complete for the PSBA·HCl salt (about 49%). The conductivity of samples was (≈0.07 S/cm) in agreement with the percent of doping obtained of the XPS analysis. Also, contact resistance was determined by circular-TLM measurement. The morphology of samples by the scanning electron microscopy (SEM) and their coating were investigated by XPS, SEM-map and energy-dispersive X-ray spectroscopy (EDX). The key benefits of this work are the preparation of conductive chiral composite with the delocalized polaron structure under green chemistry and solid-state condition, the improvement of the processability by inclusion of the 2-sec-butyl group and the use of dopant solid acid (SSPA) as dopant. - Highlights: • The solid-state synthesis of the novel chiral composites of poly[(±)-2-(sec-butyl)aniline] (PSBA) and silica-supported perchloric acid (SSPA). • It takes 120 h for complete deprotonation of PSBA.HCl salt. • Use of SSPA as dopant solid acid for the first time to attain the complete doping of PSBA. • The coating of silica surface with PSBA.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Design of a gas-solid-solid separator to remove ash from circulating fluidized bed reactors

Cyclones are one of the most common types of gas-solid separators used in circulating fluidized bed boilers. However, cyclones typically do not allow ash to leave the system through the cyclone exit, causing ash to build up in the fluidized bed and necessitating additional systems to remove ash that builds up in the bed. In this study, an alternative “disengager” gas-solid separator is proposed as a way of inherently separating small and large solids, resulting in a gas-solid-solid separation system where ash is allowed to leave the system along with gas while the desired fluidized bed material is retained. Unlike cyclones, which rely on centrifugal force to separate solids and gas, the disengager separates based on entrainment velocity of the particles. Upwards-flowing gas and particles strike a deflection plate and enter the disengaging chamber where particles with low terminal velocity such as ash fines flow with the gas, while larger particles such as sand fall to the bottom of the separator and are returned to the fluidized bed. In this study, several different proposed disengager configurations are simulated and compared to a typical cyclone using computational fluid dynamic (CFD) simulations. Furthermore, it was found that separation efficiency in the disengager is strongly influenced by the size of the deflection plate, rather than by the size of the unit itself. The predicted separation efficiency showed that compared to a cyclone, the disengager design allows significantly more ash to exit the system but retains a similar amount of desirable material. Additionally, the disengager was predicted to not suffer significantly more erosion that a cyclone.

42 ENGINEERING↗
DOE OSTI2017

Interfacial Chemistry in Solid-State Batteries: Formation of Interphase and Its Consequences

Benefitting from extremely high shear modulus and high ionic transference number, solid electrolytes are promising candidates to address both the dendrite growth and electrolyte consumption problems inherent to the widely adopted liquid-phase electrolyte batteries. However, solid electrolyte/electrode interfaces present high resistance and complicated morphology, hampering the development of solid-state battery systems, while requiring advanced analysis for rational improvement. Here, we employ an ultra-sensitive three-dimensional (3D) chemical analysis to uncover the dynamic formation of interphases at the solid electrolyte/electrode interface. While the formation of interphases widens the electrochemical window, their electronic and ionic conductivities determine the electrochemical performance and has a large influence on dendrite growth. Our results suggest that, contrary to the general understanding, highly stable solid electrolytes with metal anodes in fact promote fast dendritic formation, as a result of less Li consumption and much larger curvature of dendrite tips that leads to an enhanced electric driving force. Detailed thermodynamic analysis shows an interphase with low electronic conductivity, high ionic conductivity, chemically stable yet having a dynamic thickness and uniform coverage is needed to prevent dendrite growth. Finally, this work provides a paradigm for interphase design to address the dendrite challenge, paving the way for the development of robust, fully operational solid-state batteries.

25 ENERGY STORAGE↗
DOE OSTI2021

Three-dimensional atomic packing in amorphous solids with liquid-like structure

Liquids and solids are two fundamental states of matter. However, our understanding of their three-dimensional atomic structure is mostly based on physical models. Here we use atomic electron tomography to experimentally determine the three-dimensional atomic positions of monatomic amorphous solids, namely a Ta thin film and two Pd nanoparticles. We observe that pentagonal bipyramids are the most abundant atomic motifs in these amorphous materials. Instead of forming icosahedra, the majority of pentagonal bipyramids arrange into pentagonal bipyramid networks with medium-range order. Molecular dynamics simulations further reveal that pentagonal bipyramid networks are prevalent in monatomic metallic liquids, which rapidly grow in size and form more icosahedra during the quench from the liquid to the glass state. Furthermore, these results expand our understanding of the atomic structures of amorphous solids and will encourage future studies on amorphous–crystalline phase and glass transitions in non-crystalline materials with three-dimensional atomic resolution.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Perspective: Nonequilibrium dynamics of localized and delocalized excitons in colloidal quantum dot solids

Self-assembled quantum dot (QD) solids are a highly tunable class of materials with a wide range of applications in solid-state electronics and optoelectronic devices. In this perspective, the authors highlight how the presence of microscopic disorder in these materials can influence their macroscopic optoelectronic properties. Specifically, they consider the dynamics of excitons in energetically disordered QD solids using a theoretical model framework for both localized and delocalized excitonic regimes. In both cases, they emphasize the tendency of energetic disorder to promote nonequilibrium relaxation dynamics and discuss how the signatures of these nonequilibrium effects manifest in time-dependent spectral measurements. Moreover, they describe the connection between the microscopic dynamics of excitons within the material and the measurement of material specific parameters, such as emission linewidth broadening and energetic dissipation rate.

solar (photovoltaic), solid state lighting, photos↗
DOE OSTI2018

Toward All-Solid-State Lithium Batteries: Three-Dimensional Visualization of Lithium Migration in β-Li 3 PS 4 Ceramic Electrolyte

All-solid lithium batteries are an attractive next-generation technology that use ion-conducting solids such as ..beta..-Li3PS4 (LPS) to enable use of a lithium metal anode, which increases theoretical capacity and widens the stable voltage window over traditional lithium-ion systems. These ion-conductive solids also provide increased safety by replacing flammable liquid electrolytes. Although solid-state electrolytes are significantly more stable and dendrite-resistant than traditional liquid electrolytes, lithium anodes in all-solid systems may nevertheless grow dendrites under high stress or repeated cycling, leading to short circuits and premature battery breakdown. For this reason, we study the formation and propagation of Li metal features within solid electrolytes using synchrotron-based X-ray tomography with in-situ current-voltage cycling supported by our custom sample platform. Our results demonstrate the ability of this technique to delineate different layers of the Li/LPS/Li structure with spatial resolution approaching 1 um. At this resolution, we are able to detect expansion of voids, especially in early stages of cycling. This expansion of voids is observed throughout the volume of the symmetric cells and visually resembles propagation of cracks resulting from interactions between the Li metal and pre-existing voids in the LPS electrolyte.

25 ENERGY STORAGE↗
DOE OSTI2018

Investigation of a Solid-State Tuning Behavior in Lithium Niobate

Electric field-based frequency tuning of acoustic resonators at the material level provides an enabling technology for building complex tunable filters. Tunable acoustic resonators were fabricated in thin plates (h/λ ~ 0.05) of X-cut lithium niobate (90°, 90°, ψ = 170°). Lithium niobate is known for its large electromechanical coupling (SH: K 2 40%) and thus applicability for low-insertion loss and wideband filter applications. We demonstrate the effect of a DC bias to shift the resonant frequency by ~0.4% by directly tuning the resonator material. The mechanism is based on the nonlinearities that exist in the piezoelectric properties of lithium niobate. Devices centered at 332 MHz achieved frequency tuning of 12 kHz/V through application of a DC bias.

47 OTHER INSTRUMENTATION↗