bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gas-Reduction—Nitridation Synthesis of Nitride Phosphors for Solid-State Lighting
Authors: Suehiro Takayuki , Xie Rong-Jun , Hirosaki Naoto 
Published: February 2020

In the last decade, SiAlONs and nitridosilicates have been developed as an important class of phosphor host materials because of their great potentials for solid-state lighting (SSL). However, their low manufacturability (reaction sintering and postsynthesis grinding) is a major obstacle to the widespread use in SSL applications, triggering the intense investigations for developing more sophisticated processing techniques.
In this regard, we have developed the gas-reduction—nitridation (GRN) method, which enables the direct synthesis of nitride fine powders from the multicomponent oxide systems by using an NH3—CH4 gas mixture as a reduction—nitridation agent. The GRN-derived powders possess high phase purity, nonaggregated fine particle morphology, and very low impurity absorption throughout emissive regions, all of which meet the demands for phosphor applications. In this talk, our successful applications of the GRN process to the Eu2+-activated α-SiAlON and CASN, as well as Ce3+-activated La—Si—N phosphors for SSL will be demonstrated.
Microelectrochemical Properties of Ti(C,N) Inclusion of High Strength Martensitic Carbon Steel
Authors: Watanabe Yuta , Muto Izumi , Ohmura Tomohiko , Hara Nobuyoshi , Sugawara Yu 
Published: February 2020

High strength carbon steels are anticipated to be used in various fields. However, hydrogen embrittlement is always a big problem for high strength steels.As a result of several treatments to strengthen steel Ti(C,N) inclusions form. Although lots of reports have been conducted to in-steel inclusions such as MnS, little is known about Ti(C,N). Therefore the objective of this study is to look in to the microelectrochemial properties of Ti(C,N) inclusions and its effect on hydrogen embrittlement.
Titanium added carbon steel(0.24%C, 1.09%Mn, 0.003%S, 0.03%Ni, 0.16%Cr, 0.028% Ti, 0.031% N) was used as a specimen. The specimen was heat–treated at 1163K for 45minutes and then water-quenched. After that the specimen was kept at 493K for 1hr, and tempered. The specimen was mechanically polished with 1mm diamond paste. Electrochemical measurements were performed in a mixture of 50mM CH3COOH-50mM CH3COONa under naturally aerated conditions. The concentration of the solution above was adjusted to achieve maximum electrical conductivity, and its pH was 4.64.
The first step conducted was inclusion characterization. By searching the specimen surface with a SEM, Ti(C,N) inclusions were found to be several micrometers long and several micrometers wide. The color of the inclusion was found to be a red-pinkish color. The color of the inclusion varies from a bright color to a dim color depending on the chemical composition of the inclusion. Basically the more Ti composition the brighter the color is. Compared to a MnS inclusion Ti(C,N) inclusions are hard and are not affected by rolling.
Macroscopic polarizations were conducted to determine the macroscopic corrosion behavior of the specimen. Under weak acid conditions the specimen showed an active dissolution as soon as it was anodically polarized. On the other hand, cathodic polarizations showed the potential at which hydrogen started to form. (Fig. 1) This potential is important for determining the effect of Ti(C,N) on hydrogen embrittlement.
Microscopic polarizations were conducted to elucidate the electrochemical behavior of Ti(C,N) inclusions. Fig. 2 shows the cathodic polarizations curves of areas around Ti(C,N) inclusions and matrix areas that do not have inclusions in the target area. By comparing the open circuit potentials of the two curves we can see that areas around Ti(C,N) shows a high open circuit potential. By taking into account the potential-pH diagram of Ti(C,N) (Fig. 3) we can confirm that Ti(C,N) inclusions show a stable region in a noble region. Since Ti(C,N) are stable in a high potential, Ti(C,N) are likely to act as preferential cathodic reaction site.
Study of a Biocathode Based on the Physical Immobilization of Crude-Extract with Laccase Activity for Oxygen Reduction
Authors: López-González Berenice , Ramírez-Ledesma María Guadalupe , Cuevas-Muñiz Francisco Mherande , Arana-Cuenca Ainhoa , Ledesma-García Janet , Arriaga Luis Gerardo 
Published: February 2020

A biocathode based on the physical absorption on carbon surfaces of crude extract with laccase activity (ExLac) obtained of C. polyzona, a Mexican endemic fungus that uses barley straw as substrate, is prepared and evaluated toward oxygen reduction reaction. The biocathode electrode consists in a mixture of ExLac with 10 mM ABTS {2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)} diammonium salt and vulcan XC-72.
Electrochemical evaluation of the biocathode consisted of cyclic voltammetry CV and linear sweep voltammetry in a standard three-electrode glass cell containing a neutral aqueous media phosphate buffer solution (pH 7.4 near to blood pH) in the absence and presence of oxygen. The biocathode working electrode is constructed as follows: an ink of ExLac-ABTS/Vulcan is prepared by dispersion in deionized water and 5% Nafion solution in a ratio of 1:56:5 in a vortex and subsequently deposited onto a PVC chip and dried at room temperature.
The results showed that the biocathode catalyzes the oxygen reduction reaction better than the platinum in a neutral media in glucose presence. Further, the electrocatalyst activity of ExLac-ABTS/C is compared with that achieved by using of a biocathode prepared with commercial laccase.
One of the advantages of this type of bioelectrode array is the utilization of barley straw as a substrate in the crude extract production which is an inexpensive material that may be a good alternative for great-scale production.
Determination of Methylparaben by Square Wave Voltammetry at Boron-Doped Diamond Electrode
Authors: Mendonça Camila Domingues , Machado Sergio Antonio Spinola 
Published: February 2020

Parabens have been widely used as preservative in personal care products, foods and drugs. However, due to their endocrine disruption and carcinogenic possible action, the quantification of these pollutants in several matrices is necessary. In this way, the present work has as objective, the development of an electroanalytical methodology using square-wave technique. The target molecule is the methylparaben (MePa), which will be determined using the boron-doped diamond electrode (BDD) as the work electrode. Several operating conditions and voltammetric parameters were studied seeking greater efficiency of the technique. Under chosen conditions, the measurements were realized in an electrochemical cell containing Ag/AgCl as the reference system and a platinum foil as auxiliary electrode. Several electrolyte solutions were tested and the best results were obtained in 0.2 molL-1 phosphate buffer (pH 7.5). In such electrochemical cell, MePa showed a well-defined square wave voltammetric peak at a potential around 0.8 V, whose peak currents are linearly proportional to the MePa concentration in the electrolyte. Adequate linearity (0.9986), as shown in figure 1, in the range of 0.5 to 30 mgL-1, with limit of detection and quantification of 0.103 mgL-1 and 0.344 mgL-1, respectively, was found. The method was validated for the determination of MePa in a creek water sample, with low pollution content, obtained in Sao Carlos – SP county (S 21 59.670’ / W 047 54.183’). Spiked solutions of such water samples added to the buffer solution, showed recovery range between 68.40% a 106.15%, with a relative standard deviation (RSD) less than 6.8% (n=3). The method seemed to be sensitive to MePa and can be used for detection in others water samples. In future, we intended to use this method for detection of methylparaben in cosmetics creams.
Figure 1. Method calibration curve for determination of MePa. Concentrations: 0.5, 0.75, 1.0, 5.0, 10.0, 15.0, 20.0, 25.0, 30.0 mgL-1.
Thin Films and Superlattices in the Bi-Fe-O System Prepared by ALD
Authors: Akbashev Andrew R. , Spanier Jonathan E. 
Published: February 2020

Bismuth ferrite (BiFeO3) is one of the most technologically promising multiferroics with a simple perovskite structure and high ferroelectric and antiferromagnetic ordering temperatures. High-quality heteroepitaxial growth of BiFeO3 thin films has been demonstrated mainly by PLD, MBE, RF sputtering and metal-organic chemical vapor deposition (MOCVD). While the first three techniques listed above require ultrahigh vacuum and thus are rather expensive, particularly when used on an industrial scale, MOCVD may serve as an appropriate deposition method for the device fabrication. However, as nanoelectronic device sizes shrink, the demand for a high-precision deposition of thin layers on high-aspect-ratio structures grows stronger. ALD simply does not encounter this obstacle and can produce atomically smooth coverage on structures with extremely high aspect ratio. We will discuss the growth of BiFeO3 thin films and (Bi-O)x(Fe-O)y superlattices by ALD and the influence of the growth parameters on the phase composition of the resulting films. In short, the preparation of the films involved two stages: the deposition of the amorphous films and superlattices on Si wafers, SrTiO3(001), Nb:SrTiO3(001) at 250 C and a subsequent annealing of as-deposited films at various temperatures. Using XRD analysis and TEM imaging the annealed BiFeO3 films were demonstrated to be highly crystalline; piezoresponse force microscopy showed an expected response of the ferroelectric phase. The ALD growth of BiFeO3 will provide a new way of convenient, technologically-oriented and commercially realizable deposition of a promising multiferroic for nanoelectronic devices.
This work was supported by the NSF DMR under 1124696 and by the ARO under W911.
Investigation of Electrical Characterization of Hetero-Junctions Formed by RF Sputtered Indium Tin Oxide on Silicon
Authors: Saikumar Ashwin Kumar , Skaria Giji , Sundaram Kalpathy B 
Published: February 2020

Certain oxide semiconductors show promise as wide-scale use in optical applications owing to their low electrical resistivity and high optical transparency. One such oxide taken into our consideration here is Indium Tin Oxide (ITO). ITO is one of the most commonly used transparent conducting oxides owing to its good optical transparency and low electrical resistivity. It is also relatively easy to deposit as thin films. When deposited upon silicon, Indium and tin oxide forms good hetero-junction photovoltaic cells.
In this work, we study the electrical properties of ITO-Si hetero-junctions prepared under various deposition parameters. For this investigation, we fabricate ITO-Si hetero-junctions by RF sputtering of ITO (90% In2O3 and 10% SnO2) target. Interestingly, ITO-Si hetero-junctions can be formed on both n- and p- type Si. The studies are performed on both hetero-junction devices of ITO sputtered on n- and p- type Si wafers and characterized.
REFERENCES
[1] J.B. DuBow, D.E. Burk, and J.R. Sites, “Efficient photovoltaic heterojunctions of indium tin oxide on silicon” Applied Physics Letters 29, 494 (1976)
[2] Tiberiu Mizrah and David Adler, “Indium-Tin Oxide-Silicon Heterojunction Photovoltaic Devices” IEEE Transactions on Electron Devices, Vol. ED-24, No. 4, April 1977
[3] J. Shewchun, D. Burk, R. Singh, M. Spitzer, and J. Dubow “The semiconductor-insulator-semiconductor (indium tin oxide on silicon) solar cell: Characteristics and loss mechanisms” Journal of Applied Physics 50, 6524 (1979)
[4] H. Kobayashi, T. Ishida, K. Nakamura, Y. Nakato and H. Tsubomura, “Properties of indium tin oxide films prepared by electron beam evaporation method in relation to characteristics of indium tin oxide/silicon oxide/silicon junction solar cells” Journal of Applied Physics 72, 5288 (1992)
Redox Nanocomposite Cathode Materials for Lithium Rechargeable Batteries
Authors: Jung Sung-Kyun , Kim Hyunchul , Park Kyu-Young , Kim Hyungsub , Lee Buyngju , Park Young-Uk , Kim Haegyeom , Yoon Won-Sub , Kang Kisuk 
Published: February 2020

Only a small number of Li-containing cathode materials groups are considered for practical use in Li-ion battery systems. The possible candidates of cathode material were limited to the crystals that contain both redox-active element and lithium ion in the open framework. This concept has been conventionally considered as a standard for searching the cathode materials. But, it could be constraints to restrict the choices of materials for cathode in Li-ion battery systems. To expand the sight for seeking new positive electrode material, we suggested a novel strategy to use various kinds of Li-free transition metal ionic compounds (MX, M = transition metal, X = anion or polyanion group) as a positive electrode material by blending with a Li ionic compound (LiY, Y = anion or polyanion group) in nanoscale.[1] MX and LiY provided a redox couple and lithium ion supply for an electrochemical reaction. This concept is unconventional with general system of electrode material (Li ions and transition metal ions are in the same crystal system). In this case, transition metal ion and Li ion in the nanocomposite do not exist in the same crystal system and spatially separated as a mixture of MX and LiY.
In this paper, we will introduce and discuss about the transition metal oxide system as a redox couple among the infinite possible combinations of lithium ionic compounds and metal ionic compounds. Transition metal oxides such as FeO, MnO were considered as promising anode materials due to the earth abundance and large capacity from conversion reaction.[2] Although they have redox potential below 1 V as anode material,[3][4] we will show that this transition metal oxides can be applied to the cathode materials (3 V-class) by making nanocomposite with lithium ionic compound. To better understand the mechanisms during electrochemical cycling we have performed XPS, XANES/EXAFS analysis, allowing us to study the local environment change of Fe or Mn during the charge and discharge reaction. FeO and MnO showed different aspects during the electrochemical reaction in terms of electrochemical activity and local environment change. We will discuss about the reaction mechanism in detail.

[1] S.-W. Kim, K-Y. Nam, D.-H. Seo, J. Hong, H. Kim, H. Gwon, and K. Kang, Nano Today, 7, 168 (2012)
[2] P. Poizot, S. Laruelle, S. Grugeon, L. Dupont, and J.-M. Tarascon, Nature, 407, 496 (2000)
[3] M. Gao, P. Zhou, P. Wang, J. Wang, C. Liang, J. Zhang, and Y. Liu, J. Alloy. Compd., 565, 97 (2013)
[4] X. Li, D. Li, L. Qiao, X. Wang, X. Sun, P. Wang, and D. He, J. Mater. Chem., 22, 9189 (2012)
Lithium-Ion Transport at Electrolyte/Electrode Interface Visualized By Nanoscale Meniscus Cell Microscope
Authors: Kumatani Akichika , Takahashi Yasufumi , Inomata Hirotaka , Munakata Hirokazu , Ino Kosuke , Shiku Hitoshi , Kanamura Kiyoshi , Matsue Tomokazu 
Published: February 2020

Towards the establishment of low-carbon emission society, one urgent issue is to standardize an efficient method to store unused energy. A promised candidate is an electrochemical storage such as lithium-ion batteries. However, it is still hindered as a major problem that the lithium-ion batteries do not conduct with sufficiently high energies capabilities and stable operational cycles. In particular, it is remained as an inefficient barrier of the lithium-ion (de)intercalation at the interface between electrode and electrolyte. It is therefore necessary to determine a crucial factor which influence to the homogeneity in ion transport across the interface by in-situ measurement with nanometer resolution.
In this study, the homogeneity in local ion transport of LiFePO4 thin electrodes is investigated by a nanoscale meniscus cell microscope (NMCM). It is a newly established scanning probe microscopy with a nano-size pipet with electrolyte and a reference-electrode.1 As the pipet is in proximity of the LiFePO4 electrode, a meniscus is created. Then, ionic current is only measured through the meniscus when the voltage is applied between reference and LiFePO4electrodes, as shown in Figure 1(a). When the pipet is scanned through the interface in nanometer step, a mapping of the ion current distribution in lithium (de)intercalation is obtained with topographical information in Figure 1 (b). Further, as the pipet was pinned at specific area, it allows us to study the localized ion transport by cyclic voltammetry or charge /discharge process. This new analytic technique will reveal a bottleneck of the ion transport in the materials. leading to the creation of electrode with homogeneous ion transport.

Reference:

(1) Y. Takahashi, et al., under review.
Imaging and Spectroscopy of Pristine and Cycled Li2MnO3
Authors: Phillips Patrick J , Iddir Hakim , Abraham Daniel P , Klie Robert F 
Published: February 2020

Li-ion batteries have yet to reach their full application potential due to their inherent cycling performance issues, such as voltage instability and capacity fading, while fundamental questions remain unanswered regarding the mechanisms responsible. However, Mn-based layered oxides continue to be promising candidates for cathodes in high-energy-density Li batteries given their high voltage and high discharge capacities. A significant impediment to gaining insight into these layered oxides lies in their complexity and inhomogeneity. Thus, the focus of the present contribution will be on the parent material, Li2MnO3, which shows cycling characteristics similar to its more complex offspring. Scanning transmission electron microscopy (STEM) and spectroscopy are used to characterize structural and electronic properties of both pristine and cycled material.
STEM-based methods are quickly becoming the most promising characterization tools for these and similar materials, owed largely to the wide-range of techniques available on advanced STEM instruments, including the direct imaging of both heavy and light elements, and both energy-dispersive X-ray (EDX) and electron energy loss (EEL) spectroscopies. Imaging modes such as high/low angle annular dark field (H/LAADF) and annular bright field (ABF) are exploited to image heavy atomic columns, strain contrast, and light atomic columns, respectively. Additionally, electron energy loss spectroscopy along with calculations based on density functional theory are used to probe the local electronic structure by monitoring the O K- and Mn L-edges, which can be used to track changes to both the O content and the Mn valence. Thus, the focus will remain on the structural and electronic evolution of the pristine layered oxide explored by combining spectroscopy and atomic-scale imaging with various in situ microscopy techniques and ex situ electrochemical cycling. Specifically, features such as the atomic ordering of Mn/Li atoms, O vacancy evolution, and Mn valence will be of particular interest.
Studies of the Effect of Varying Prop-1-Ene-1,3-Sultone (PES) Concentration on Li-Ion Batteries
Authors: Nelson Kathlyne , Xia Jian , Dahn Jeff 
Published: February 2020

Introduction

Electrolyte additives are the most effective way to improve the calendar life and cycling performance of lithium-ion batteries. Vinylene carbonate (VC) is perhaps the most well-known additive for Li-ion batteries and has been shown to be useful during the solid electrolyte interphase (SEI) formation [1], which can result in longer calendar life and reduced irreversible capacity (IRC). However, it has been shown that the performance of cells containing VC decreases at high temperatures and high voltages. Sulfur-containing additives have been studied in hopes to overcome the temperature sensitivity of VC. Prop-1-ene-1,3-sultone (PES) was found to have smaller IRC than VC-containing cells and was suggested to be an SEI forming additive [2]. In this study, we show that PES is a useful additive for Li-ion pouch cells and suggest that PES, when used in combination with other additives, may be more effective than VC at achieving long lifetimes and high cycling performance.

Experimental

Li[Ni1/3Mn1/3Co1/3]O2 (NMC)/graphite pouch cells made with 1M LiPF6in EC:EMC 3:7 (by weight) and varying amounts of PES were studied using ultra high precision coulometry and storage experiments. In addition, gas evolution measurements employing Archimedes principle and electrochemical impedance spectroscopy (EIS) measurements were performed. The PES-containing cells were compared to the same control electrolyte containing 2% VC.

Results

Figure 1 shows a preliminary set of results from both storage and cycling experiments of PES-containing cells compared with control electrolyte and 2% VC-containing cells. The dotted line in Figures 1a, d, and e indicates the value for 2% VC. Figure 1a shows the gas evolution during formation at 40°C and Figures 1b and c show gas evolution during storage at 60°C and 40°C, respectively. Cells containing 2, 4 and 6% PES show smaller gas during formation than that of 2% VC and all concentrations of PES studied show significantly smaller gas during 40°C and 60°C storage than VC-containing cells. The most prominent advantage of PES compared to VC is the extremely low gas evolution during high temperature storage. Figure 1d shows the voltage drop during storage from 4.2 V at 40°C for 500 hours. Figure 1e shows the average coloumbic inefficiency (CIE) during the last three cycles of cycling between 2.8 V and 4.2 V at C/20 and 40°C. Through the voltage drop and CIE, it is clear that 2% PES appears to be as good as 2% VC.
This work suggests that PES is a viable alternative to VC and is superior during high temperature storage. PES may also prove to be beneficial in combination with other additives.

References

[1] M. Broussely, Ph. Biensan, F. Bonhomme, Ph. Blanchard, S. Herreyre, K. Nechev and R.J. Staniewicz, J. Power Sources, 146, 90 (2005).
[2] B. Li, Y. Wang, H. Rong, Y. Wang, J. Liu, L. Xing, M. Xu and W. Li, J. Mater. Chem.
A, 1, 12954 (2013)
Synthesis and Crystal Structure of Lithium Iron Titanium Oxides Li1/2-+1/2xFe5/2-3/2xTixO4 with 0 ≤ x ≤ 1.666
Authors: Mukai Kazuhiko , Kato Yuichi , Horibuchi Kayo , Nakano Hideyuki 
Published: February 2020

Li[Li1/3Ti5/3]O4 (LTO) is an ideal negative electrode material for long-cycle life lithium-ion battery (LIB), because of its “zero-strain” character [1]. In the LTO crystal lattice with Fd-3m space group, Li+ ions occupy both tetrahedral 8a and octahedral 16d sites, while Ti4+ ions sit the 16d site. We, thus, expect a solid solution compound Li1/2+1/2x
Fe5/2–3/2x
Ti
x
O4 (LFTO) between LTO and Fe[Li1/2Fe3/2]O4 via an intermediate spinel compound Li1/2Fe1/2[Li1/2Fe1/2Ti]O4. Fe[Li1/2Fe3/2]O4 is known to be one of the ferrites, which exhibit a soft ferromagnetic behavior. Here we report the results of powder X-ray diffraction (XRD) and electron diffraction (ED) measurements, and Raman spectroscopy analyses on the LFTO samples with 0 ≤ x ≤ 1.666.
According to XRD measurements, all the LFTO samples were assigned as a spinel-framework structure. For the x = 0 sample, the extra diffraction lines were clearly observed in addition to the normal diffraction lines in the Fd-3m. The extra diffraction lines are attributed to the superlattice diffraction lines due to the ordering between Li+ and Fe3+ ions at the octahedral site. As x increases from 0.25, such superlattice diffraction lines disappear, but, surprisingly, superlattice diffraction lines appear again at x > 1.2. The crystal structure at x £ 0.25 and 1.2 < x < 1.6 are assigned as the P4332 space group. Combining with the result of x dependence of cubic lattice parameter (a
c), the crystal structure of LFTO is classified into the four regions; (I) regular spinel structure of Fd3-m with x > 1.55, (II) superlattice spinel structure of P4332 with 1.2 ≤ x ≤ 1.55, (III) regular spinel structure of Fd3-m with 0.25 < x < 1.2, and (IV) superlattice spinel structure of P4332 with x ≤ 0.25.
Acknowledgement
This work was supported by Grant-in-Aid for Scientific Research (C), 25410207, MEXT, Japan.

References

[1] T. Ohzuku, A. Ueda, and N. Yamamoto, J. Electrochem. Soc., 142 (1995) 1431.