bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ternary Metal Fluorides As High-Energy Cathodes with Low Cycling Hysteresis
Authors: Wang Feng , Kim Sung-Wook , Graetz Jason 
Published: February 2020

Transition metal fluorides (MFx) are promising for use as high-capacity cathodes in rechargeable lithium batteries for large-scale applications, such as electric vehicles and grid-scale storage, but energy-efficiency and kinetics related issues remain a major hurdle to their commercial use. Cu based fluorides are particularly attractive due to the 3.55 V redox potential and extraordinarily high specific energy (1874 Wh/kg). Here we report on the synthesis, structural and electrochemical properties of new ternary metal fluorides (M1yM21-yFx: M1, M2 = Fe, Cu), which may overcome these issues. By substituting Cu into the Fe lattice, forming the solid solution CuyFe1-yF2, reversible Cu and Fe redox reactions were achieved with surprisingly small hysteresis (<150 mV; Figure 1). This finding indicates that cation substitution may provide a new pathway for tailoring electrochemical properties of conversion electrodes.
The Li storage/release mechanisms and limits to cycling stability of CuyFe1-yF2 were investigated by combining electrochemical measurement with comprehensive structural and chemical analysis using in-situ X-ray absorption spectroscopy, X-ray diffraction, and transmission electron microscopy-electron energy loss spectroscopy (TEM-EELS). The lithium reaction process is much more complicated in CuyFe1-yF2 than the binary metal counterparts (i.e. FeF2, CuF2) [2-4]. Some of the recent results on synthesis, structural and electrochemical characterization of the ternary metal fluorides will be presented. Detailed lithium reaction mechanisms, and Cu-loss related issues along with possible remedy solutions in the CuyFe1-yF2system, will be discussed.
[1] Wang et al., “Ternary Metal Fluorides as High-Energy Cathodes with Low Cycling Hysteresis”, Nat. Commun.6:6668 (2015).
[2] Wang et al., “Conversion Reaction Mechanisms in Lithium Ion Batteries: Study of the Binary Metal Fluoride Electrodes”, J. Am. Chem. Soc., 133, 18828 (2011).
[3] Wang et al., “Tracking Li Transport and Electrochemical Reaction in Nanoparticles”, Nat. Commun., 3, 1201(2012).
[4] Hua et al., “Comprehensive Study of the CuF2 Conversion Reaction Mechanism in a Lithium Ion Battery”, J. Phys. Chem. C 118, 15169 (2014).

Figure 1
Long-Term Stability of Quinone Electrolytes in Aqueous Flow Batteries
Authors: Gerhardt Michael R. , Tong Liuchuan , Marshak Michael P. , Gordon Roy G. , Aziz Michael J. 
Published: February 2020

Quinone-based flow batteries are attractive candidates for large-scale electrical energy storage, as quinones can be inexpensive, exhibit rapid redox kinetics, and require no electrocatalyst [1-3]. We present the evaluation of several quinone negative electrolyte materials for use in a flow battery with a positive electrolyte containing bromine and hydrobromic acid. Several substituted quinones are shown to undergo reversible two-electron reduction and oxidation in acidic aqueous solution, with tunable reduction potentials. Some are found to be stable in the presence of bromine, while others undergo decomposition reactions. One stable substituted quinone is currently being tested in a quinone-bromide flow battery. As of writing this abstract, the cell exhibits a peak galvanic power density above 700 mW/cm2, an average round-trip energy efficiency of 70%, and current efficiency of 95% as tested to 30 constant-current charge-discharge cycles at 0.25 A/cm2. Further cycling will be reported.
[1] B. Huskinson, M.P. Marshak, C. Suh, S. Er, M.R. Gerhardt, C.J. Galvin, X. Chen, A. Aspuru-Guzik, R.G. Gordon and M.J. Aziz, “A metal-free organic-inorganic aqueous flow battery”, Nature 505, 195 (2014), http://dx.doi.org/10.1038/nature12909
[2] B. Huskinson, M.P. Marshak, M.R. Gerhardt and M.J. Aziz, “Cycling of a quinone-bromide flow battery for large-scale electrochemical energy storage”, ECS Trans. 61, 27 (2014)
[3] B. Yang, L. Hoober-Burkhardt, F. Wang, G.K. Surya Prakash, and S.R. Narayanan, J. Electrochem. Soc. 161, A1371 (2014).

Figure 1.
a. Polarization curves and b. galvanic power density as a function of current density for a substituted quinone – bromide flow battery at three different states of charge (SoC). The peak galvanic power density exceeds 0.7 W/cm2at 90% SoC.

Figure 2. Cell voltage during constant current charge-discharge cycling of a substituted quinone-bromide flow battery at ± 0.25 A/cm2. Voltage cutoffs were set at 1.3 V and 0.3 V. The time window chosen shows cycles 14-24 of a 30-cycle experiment.

Figure 1
Non-Chromatographic Isolation of Mixed-Metal Nitride Clusters in Larger Carbon Cages
Authors: Stevenson Steven 
Published: February 2020

There is a growing interest in mixed-metal nitride metallofullerenes. Prior to exploring their properties and applications, these mixed-metal endohedrals must first be purified. To date, their isolation has been difficult. Hurdles to overcome include their (1) low abundance in soot extract, (2) their co-synthesis with a complex mixture of many types of fullerenes and metallofullerenes, and (3) their HPLC co-elution with contaminant species. In this presentation, we reveal a separation methodology to minimize and/or avoid HPLC (e.g., recycling HPLC), which is the conventional (i.e., literature) method for isolating mixed-metal nitride endohedral metallofullerenes. We also discuss strategies and details of our purification approach, which exploits differences in their reactivity with Lewis acids and aminosilica for their selective removal from extracts and subsequent isolation.
Resonant Raman Scattering Studies of SWCNT Templated Extreme Nanowires of Hgte and Pbi
Authors: Smith David Christopher , Spencer Joe , Sloan Jeremy , Faulques Eric 
Published: February 2020

By filling the central pore of a single walled carbon nanotube (SWCNT) it is possible to form nanowires of a wide range of inorganic materials that are one unit cell in diameter. These are extreme nanowires, i.e. at the limit of miniaturisation of nanowires. Nanowires of these diameters show extreme quantum confinement effects and in some cases have crystal structures which cannot be stabilised as 3D crystals. Wide ranges of scientifically and technologically interesting materials have already been used to produce such nanowires. These include ferromagnetic materials, e.g. Fe and Co, phase change materials, e.g. GeTe, ferroelectric materials, e.g. SbSeI, and semiconductors, e.g. HgTe. It is likely that extreme nanowires will have entirely new properties, not just modified versions of the properties of the materials from which they are formed. Such properties would be interesting both fundamentally and technologically. However, as yet there has only been very limited characterisation of the properties of nanowires formed inside single walled carbon nanotubes and the fundamental physics is not yet really understood.
We will present a comprehensive study of the Raman spectra of the vibrational modes of HgTe extreme nanowires inside single walled carbon nanotubes alongside atomic resolution TEM of the samples. Both TEM and the vibrational spectra clearly indicate that HgTe forms nanowires with an entirely new crystal structure when infiltrated into 1.3-1.4nm diameter SWCNTs. The strength of the Raman scattering is strongly dependent on incoming photon energy, with a strong resonance centred at 1.77eV which tails off more slowly to low energy than to high. Whilst all of the fundamental and combination modes are resonant at the same basic energy, the shape of the resonance varies for different features. It is clear that the form of the resonance has a lot to tell us about the electron-phonon coupling in these 1-Dimensional structures. We will present the dependence of the Raman scattering on excitation and scattered polarisation, which is entirely in line with what would be expected for nanowires. However the temperature dependence of the Raman scattering is anomalous, showing a decrease in scattering intensity by a factor of ten with increasing temperature from 4K to 300K. We will also present results of electrochemically gated Raman scattering from HgTe nanowires which allow us to determine the band alignment of the template tubes and extreme nanowire. In addition to a comprehensive discussion of Raman scattering from HgTe nanowires, we will also present Raman scattering from PbI2 and CoI2 nanowires formed in SWCNTs and prove that the physics demonstrated by the HgTe nanowires is more generally applicable.

Figure 1
The Origins and Characteristics of the Threshold Voltage Variability of Quasi-Ballistic Single-Walled Carbon Nanotube Field-Effect Transistors
Authors: Cao Qing 
Published: February 2020

Ultra-scaled transistors based on single-walled carbon nanotubes are identified as one of the top candidates for future microprocessor chips as they provide significantly better device performance and scaling properties than conventional silicon technologies. From the perspective of the chip performance, the device variability is as important as the device performance for practical applications. Here we presents a systematic investigation on the origins and characteristics of the threshold voltage (V
T) variability of scaled quasi-ballistic nanotube transistors. Analysis of experimental results from variable temperature measurement as well as gate oxide thickness scaling studies shows that the random variation from fixed charges present on the oxide surface close to nanotubes dominates the V
T variability of nanotube transistors. The V
T variability of single-tube transistors has a figure of merit that is quantitatively comparable with that of current silicon devices; and it could be reduced with the adoption of improved device passivation schemes, which might be necessary for practical devices incorporating multiple nanotubes, whose area normalized V
T variability becomes worse due to the synergic effects from the limited surface coverage of nanotubes and the nonlinearity of the device off-state leakage current, as predicted by the Monte Carlo simulation.
Nondestructive Production of Magnetic Graphene Towards Energy Applications
Authors: Imae Toyoko , Ahmed Mahmoud Mohamed Mahmoud , Ujihara Masaki 
Published: February 2020

Graphene can be prepared from a graphite intercalation compound (GIC)1 with acceptor-type intercalator, FeCl3.2 When the FeCl3–GIC is treated with primary amines at 90 °C for 6 h, the GIC expands to a few layers.3 The expansion is further facilitated, as the alkyl chain of primary amines becomes longer, while tertiary amines cannot penetrate inside the GIC because of their structural steric hindrance. The primary amine adsorbed in the GIC is oriented to form a bilayer by an indirect reactions among FeCl3–graphene–amine, and this process plays an important role in the expansion of the GIC, in contrast to the reaction of primary amines with donor-type GICs.4 Then the expanded-GIC is sonicated to exfoliate the graphene sheets. The obtained material exhibited a superparamagnetic property due to the remaining iron compounds. This approach using FeCl3–GIC and primary amine is preferable for the mass production of graphene because of the mild reaction conditions and the short treatment time for exfoliation from the chemically stable FeCl3–GIC. Moreover, the magnetization of graphene nano-composites could be useful for magnetic-recovery processes, electromagnetic heating, and the other electrochemical applications

References:

1. Zhao, W.; Tan, P. H.; Liu, J.; Ferrari, A. C., Intercalation of few-layer graphite flakes with FeCl3: Raman determination of Fermi level, layer by layer decoupling, and stability. Journal of the American Chemical Society 2011, 133 (15), 5941-5946.
2. Zhan, D.; Sun, L.; Ni, Z. H.; Liu, L.; Fan, X. F.; Wang, Y.; Yu, T.; Lam, Y. M.; Huang, W.; Shen, Z. X., FeCl3‐Based Few‐Layer Graphene Intercalation Compounds: Single Linear Dispersion Electronic Band Structure and Strong Charge Transfer Doping. Advanced Functional Materials 2010, 20 (20), 3504-3509.
3. M. Ujihara, M. M. M. Ahmed, T. Imae and Y. Yamauchi, Massive-exfoliation of magnetic graphene from acceptor-type GIC by long-chain alkyl amine. J. Mater. Chem. A, 2014, (2), 4244 - 4250.
4. Maluangnont, T.; Bui, G. T.; Huntington, B. A.; Lerner, M. M., Preparation of a homologous series of graphite alkylamine intercalation compounds including an unusual parallel bilayer intercalate arrangement. Chemistry of Materials 2011, 23 (5), 1091-1095.
Corrosion Behavior of Casing Steels in Cement Synthetic Pore Solution Exposed to High Pressure CO2 and H2S
Authors: Feng Ruishu , Beck Justin , Hall Derek M. , Buyuksagis Aysel , Ziomek-Moroz Margaret , Lvov Serguei N. 
Published: February 2020

As deeper wells drilled for oil and gas extraction encounter higher pressures, temperatures, and concentrations in the downhole environment, it becomes increasingly important to consider the integrity of the casing that provides both support and isolation of the well. These casings are commonly cemented to provide better sealing, and the alkaline environment provided by the pore water at the cement-casing interface typically puts the steel in a passive region. However, exposure to acid gases can cause degradation of the cement and thus lower the pH at the steel surface. Further, many formation waters are brines containing high concentration of chlorides. This increases the risk of corrosion and failure of the well casing. With these issues in mind, a corrosion study was initiated to investigate the corrosion behavior of grade L-80 casing steel in cement synthetic pore solutions in contact with CO2 and H2S. Experimental approaches consisted of two stages. In the first stage, a Class H well cement was exposed to a 5 wt% NaCl brine in contact with CO2 and H2S at 85 °C for 200 hours. At the end of the exposure time, the pore water of the exposed cement was sampled and analyzed qualitatively and quantitatively. This chemical analysis was used for preparing a cement synthetic pore solution (CSPS) for corrosion testing. In situ electrochemical measurements, performed for the L-80 steel samples in the CSPS at 85 °C, included linear polarization resistance, electrochemical impedance spectroscopy, cyclic voltammetry, and Tafel analysis. Additionally, ex situ surface analyses using scanning electron microscopy, X-ray energy dispersive spectroscopy, and X-ray diffraction were performed for the corroded samples. Mass loss measurement coupons were also used to confirm the electrochemical results.
Effect of Tropical Atmosphere on Corrosion of Different Metals: Corrosivity Measurements of Singapore
Authors: Wijesinghe Sudesh Lakshitha , Tan Zixi 
Published: February 2020

Corrosion influences and intrudes many parts of our lives. It can cause dangerous and expensive damages. Singapore obviously faces corrosion consequences though there is no direct evidence or record to justify how aggressive and diverse Singapore atmosphere is in terms of corrosion. However, now there is some light to shed these doubts as standardised atmospheric exposure tests have been established in Singapore. Atmospheric exposure test sites were setup at three locations of Singapore to represent marine, industrial and urban atmospheres or their mixtures. Salient atmospheric constituents or parameters like time of wetness, Cl-, SO2, NO2, O3, HNO3 have been measured in all sites over a period of time to categorise corrosivities of particular atmospheres. The effect of atmosphere on corrosion of Fe, Cu, Al and Zn also has been investigated and quantified. Subsequently, “estimated” and “determined” corrosivity values of Singapore according to ISO 9223:2012 were measured and recorded.
Synthesis of ALD Tungsten Trioxide Thin Films from W(CO)6 and H2O Precursors
Authors: Zhang Kai , McCleese Christopher , Lin Pengtao , Chen Xin , Morales Monica , Cao Wei , Seo Felix J. , Burda Clemens , Baumgart Helmut 
Published: February 2020

Tungsten trioxide (WO3) thin films are extensively investigated for their remarkable semiconducting properties in electrochromics, microelectrics, selective catalysts, solar cells, gas-sensors and environmental engineering. In addition, WO3 has been particularly developed for electrochromic applications, such as smart windows for green buildings and airplanes, rear mirrors in automobiles, displays, and electro-devices.WO3 thin films have been fabricated by various methods, including physical vapor depostion (PVD), pulsed vapor deposition (PLD), RF magnetron sputtering deposition, and electrodeposition [1, 2].
Atomic layer deposition (ALD) is a novel process to synthesize variaous thin films, where the sequential alternating vapor pulses of chemical precursors are introduced into the ALD reaction chamber, one at a time. Each precursor pulse was separated by inert gas, such as Ar or N2. The excess precursors and reaction by-products were evacuated by vacuum pump from the ALD reaction chamber. The precursor is fully reacted with only one monoatomic layer on the reacting surface through a surface saturating self-terminationg process. Therefore, the ALD technique produces extremely uniform and conformal films in atomic level thickness. In general ALD has been shown to be able to generate reproducible and well-defined thin films of binary oxides, nitrides, and sulfides. In recent years ALD has been used to deposit pure elemental metals, new types of ternary and quarternary materials.
Presently only a few processes have been reported on the synthesis of WO3 films by atomic layer deposition (ALD) so far. ALD WO3 thin films have been deposited using WF6 and H2O as precursors. WO3 films have also been deposited by ALD using tungsten hexacarbonyl (W(CO)6) and ozone as reactant precursors for tungsten and oxygen.
In this work, we report on the synthesis of WO3 thin films on Si and quartz substrates by thermal ALD using a cross-flow reactor, with W(CO)6 and DI water as the chemical ALD precursors for tungsten and oxygen, respectively. This was followed by 600 oC furnace annealing in regular atmosphere. Characterization of WO3 thin films has been performed using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), energy-dispersive X-ray spectroscopy (EDX), UV-VIS-NIR spectrometer, Raman spectroscopy (RS).
Figure 1 shows the XRD pattern of the ALD WO3 samples obtained after furnace annealing at 600 oC under atmospheric conditions. All the diffraction peaks can be indexed into the monoclinic structure of the WO3 phase [space group: P21/n (14)], which is consistent with PDF 83-0950.
References:
J. Malm, T. Sajavaara, and M. Karppinen, Chem. Vap. Deposition 18, 245 (2012).

P. Tägtström, P. Mårtensson, U. Jansson, and J.-O. Carlsson, J. Electrochem. Soc. 146, 3139 (1999).

Figure 1
(Invited) Atomic Layer Deposition of Nanophase Materials for Electrical Energy Storage
Authors: Meng Xiangbo , Elam Jeffrey W 
Published: February 2020

Batteries, as one of the most successful electrochemical electrical energy storage (EES) devices, hold great promise to boost widely implementation of renewable clean energies such as wind and solar power in three major domains: portable electronics, transport, and smart grids. To date, state-of-the-art lithium-ion batteries (LIBs) are dominant in consumer electronics, but still not applicable for electrical vehicles and smart grids in terms of energy density, cost, safety, and stability. In this context, huge research effort has been undergoing in pursuing cost-effective, high-energy, and robust batteries as next-generation EES devices.
In the past few years, atomic layer deposition (ALD), a traditional thin film technique in semiconductor industries, has been identified as a new thrust for advanced EES and demonstrated powerful capabilities in addressing existing difficulties with various advanced battery technologies. Benefited from its unique mechanism, ALD now has become a versatile and irreplaceable tool for developing a large range of novel nanophase materials. The resultant nanoscale materials are playing more and more important roles in seeking new clean energy solutions. In the first place, ALD enables to provide a large variety of high-efficient electrodes (anodes and cathodes) by nanoarchitecturing energy-related materials. Secondly, ALD is particularly capable of finely tailoring battery interfaces for improved battery safety and stability, distinguishing its unrivalled quality from other methods in accurately controlling sub-nano to nanoscale ultrathin films with the most desired properties. In addition, ALD shows notable potential in constructing superionic lithium conductors as solid-state electrolytes for reliable battery safety, featuring its exceptional ability in tuning materials composition and crystallinity of complex compounds. In this invited talk, we will summarize and illustrate the various demonstrable strategies of ALD for next-generation LIBs and beyond Li-ion technologies (e.g., lithium-sulfur, lithium-oxygen, and sodium-based batteries), and highlight the most successful accomplishments of ALD in batteries. We will also give some outlooks on ALD future research trends and its opportunities in helping accomplish our energy missions.
Atomic Layer Deposition and in-Situ Characterization of Yttrium Oxide and Yttria-Stabilized Zirconia
Authors: Lecordier Laurent 
Published: February 2020

Y2O3 is an attractive rear-earth oxide due to its large permittivity (~14-18), high refractive index above 1.9, optical transparency over a wide spectral range (0.2-8µm), large bandgap of 5.8eV and excellent thermodynamic stability. Additionally, when co-deposited with ZrO2, it leads to yttria-stabilized zirconia (YSZ), a dense ionic conductor widely used as an SOFC electrolyte. The depositions of Y2O3and YSZ by thermal ALD are therefore important in the context of achieving dense pinhole-free thin films (<50nm) that can potentially be applied with excellent conformallity over high aspect ratio 3D nanostructures either for electronic, optical or energy applications.
In this paper, Y2O3 and YSZ thin films are thermally deposited by ALD in a commercial Ultratech Savannah reactor. Tris(ethylcyclopentadienyl)yttrium -Y(EtCp)3 - heated at 120˚C (0.15 Torr vapor pressure) - is used as a precursor with N2 carrier bubbled through via a Low Vapor Pressure Delivery system. Additionally, tetrakis(dimethylamido)zirconium TDMAZr is selected for ZrO2 deposition while H2O is the co-reactant. A quartz crystal microbalance has been implemented in order to rapidly characterize the ALD process space from 150 to 300˚C as a function of Y(EtCp)3 and H2O doses. In-situ spectroscopic ellipsometry data are also collected in order to measure the evolution of the optical film properties with temperature.
In the case of Y2O3, a soft saturation of the growth per cycle vs. Y(EtCp)3 bubbling time is observed with a GPC of 1.6Å/cycle at 250˚C. The non-uniformity across 150 mm wafers decreases to ~2% at an optimal Y(EtCp)3 dose. The GPC increases monotonically with temperature with no apparent plateau between 150 to 300˚C. The optical index remains stable at 1.92 above 200˚C. The Y2O3film stoichiometry is confirmed by RBS while SIMS measurements indicate a carbon content below 0.1%.
Uniform YSZ thin films were deposited and the yttria to zirconia composition is accurately controlled by adjusting the ratio of TDMAZr to Y(EtCp)3 cycles. In-situ measurements confirm the growth of Y2O3 on ZrO2, and vice-versa, without evidence of nucleation retardation when alternating the chemistries. The Y:Zr mass ratio monitored by QCM appears consistent with the Y2O3 to ZrO2 ALD cycle ratio and is verified with ex-situ XPS. XRD measurements were done on Y2O3 and YSZ samples to characterize the film crystallinity.
Overall both Y2O3 and YSZ ALD processes prove robust and reproducible with negligible contamination and no apparent sign of thermal decomposition of the precursor.