bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation into the Corrosion Mechanisms and Effective Inhibitor Additions for Zinc-Magnesium-Aluminium (ZMA) Alloys
Authors: Lewis Thomas , Sullivan James , Cooze Nathan , Gallagher Callum , Elvins Jonathon , Prosek Tomas , Thierry Dominique 
Published: February 2020

The use of zinc-magnesium-aluminium (ZMA) alloys is increasing in popularity within the coated steel industry due to the potential advantages it can offer. As such, a collaboration of work involving three differing ZMA alloy coated steels were studied using the scanning vibrating electrode technique (SVET) and novel in situ time-lapse optical microscopy whilst immersed in a 1% NaCl electrolyte, facilitating the investigation of each microstructure. The collation of data demonstrated preferential corrosive attack of the eutectic phases amongst each of the alloy compositions, and more specifically the MgZn2 lamellae, succeeded by the corrosion of Zn-rich dendrites.
The use of SVET enabled an estimation of mass loss from each alloy, and when correlated with the time-lapse data, revealed a reduction in magnitude of corrosion with increasing content of Mg and Al alloy additions. The improvement in corrosion performance was likely a result of increased levels of both MgO and Al2O3 existing at the alloy surface, thereby restraining the corrosion event kinetics. A corrosion inhibitor in the form of Na3PO4 introduced to 1% NaCl electrolyte at varying concentrations exhibited marked effects on the corrosion of the selected ZMA alloy, as evidenced by both SVET and time-lapse microscopy data sets.
Approximations based on the measured SVET data showed that sodium phosphate additions diminished the corrosion activity, the extent of which was dependant on the chosen concentration. The time-lapse images establish suitable correlation with the estimated mass loss results at pH 7, whereby images indicated phosphate precipitation at anodic sites, and thus their passivation. Based on these observations, it can be realised that sodium phosphate inhibitor additions have an appreciable effect on corrosion behaviour within this particular alloy system.
Effects of Flow on Protective Scales Formation in a CO2 Saturated Brine Environment
Authors: Hassan SK Mobbassar , Abdullah Aboubakr Moustafa , Laycock Nicholas , Williams David E , Ingham Bridget 
Published: February 2020

A significant amount of literature exists demonstrating the effect of CO2 on corrosion scale formation under non-flow conditions and its pH and temperature dependent protectivity. However, little information is available on the effects of flow on the nature and protectivity of corrosion scale. This work demonstrates the effects of flow on 4 different oil-field grade steels of varying chemistry (in terms of micro-alloying) and microstructures (ferritic /pearlitic and martensitic), in a CO2 saturated (1bar) brine (0.5 M NaCl) environment under conditions (pH = 6.3 and temperature = 80 oC) which generate a significantly compact and protective scale under non-flow conditions. Flow was introduced in the range of 0 - 3000 RPM via a rotating disk electrode (RDE) type arrangement which has been customized to comply with the needs of the experiment. The effect of flow was electrochemically characterized by potentiostatic current density (id
) vs time (t) measurement where Pt and Ag/AgCl were used as counter electrode and reference electrode respectively. Higher RPM (≥1000) indicated distinct characteristics compared to the lower RPMs (≤100) with a transition of i vs. t behavior observed around 500 RPM. Higher RPMs seemed to modulate the mechanism of the nucleation stage of scale formation and induce a relatively sluggish formation of protective scale by delaying the crystal growth process. Two plain carbon steels, J55 (ferritic /pearlitic) and L80 (Martensitic), did not show any qualitative difference in their i vs. t characteristics as function of flow. However, L80 steel required a longer time for crystal growth and achieving a similar degree of protection through scale formation compared to J55. 1 wt.% Cr micro-alloyed steels showed a lower current density compared to the plain carbon steels at the very early stage of scale formation; however the eventual protectivity of the scales formed on the plain carbon steels appeared to be much better on the basis of i vs t characteristics. Further characterizations of the scales in terms of phase identification, morphology and thickness by XRD, SEM and profilometry are in progress.

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(Invited) Industrial High Efficiency Perc Solar Cells
Authors: Xing Guoqiang 
Published: February 2020

While the first paper describing Passivated Emitter and Real Cell (PERC) appeared in 1989, the PERC cell structure was conceived several years earlier. After many years industrial development, world-wide PERC mass production capacity has gradually grown to about 2.5 GW by the end of 2014; thereafter the PERC installations experienced a rapid outburst to over 10 GW by Q1 2016. In this paper, we update the latest development of PERC technology and analyze the technical and economic reasons for PERC’s rapid growth in market shares, such as maturity in mass production equipment and materials, solution of light induced degradation (LID) of PERC cells. Furthermore we analyze different efficiency loss mechanisms of our current 21% mass production PERC cells, and establish roadmaps for PERC cells to reach 23% and beyond. PERC module performance and total cost of ownership of PERC technology will be discussed as well.
Theoretical Investigation of Unique Properties in Perovskite Solar Cell Materials
Authors: Yin Wan-Jian , Yan Yanfa , Wei Su-Huai 
Published: February 2020

The emergence of perovskite (typically CH3NH3PbI3) solar cells revolutionized the field not only because of their rapidly increased efficiency, but also flexibility in material growth and architecture. The superior performance of the perovskite solar cell suggested that perovskite materials possess intrinsically unique properties.
In this talk, I will present our recent theoretical investigations into the structural, electrical, and optical properties of halide perovskite materials, especially CH3NH3PbI3, in relation to their applications in solar cells. (i) the optical transitions of CH3NH3PbI3 is direct p-to-p transition, which combines the advantage of the first- and second-generation solar cell materials, responsible for the strong optical absorption [1]; (ii) different from common p-type thin-film solar cell absorber, it exhibits flexible conductivity from good p-type, intrinsic to good n-type depending on the growth conditions; (iii) dominating intrinsic defects create only shallow defect levels, which partially explain the long carrier electron-hole diffusion length and high open-circuit voltage[2]; (iv) molecular dynamics simulations show that the structure of pristine CH3NH3PbI3 is much more distorted than the inorganic archetypal thin-film semiconductor CdTe. However, the structure disorders from both thermal fluctuation and grain boundaries (GBs) introduce no deep defect states within the band gaps, therefore, the polycrystalline show single-crystal-like properties; (v) although GBs introduce no gap states, they could act as hole trap state and increase the carrier effective mass. Cl and O can spontaneously segregate into GBs and passivate those defect levels and deactivate the trap state [3]. The unusual physical properties of perovskite are attributed to the unique electronic structures of halide perovskite: the strong coupling between cation lone-pair s orbital and anion p orbitals and the large atomic size of constitute cation atoms.
The correlation of experimental observations and the verification of our theoretical results, which may further guide experimental research will also be discussed [4].
[1] W.-J. Yin, T. Shi and Y. Yan, Adv. Mater. 26, 4653 (2014).
[2] W.-J. Yin, T. Shi and Y. Yan, Appl. Phys. Lett. 104, 063903 (2014).
[3] W.-J. Yin, H. Y. Chen, T. Shi, S.-H. Wei, and Y. Yan, Adv. Elect. Mater. 1, 1400044 (2015).
[4] W.-J. Yin, J.-H. Yang, J. Kang, Y. Yan and S.-H. Wei, J. Mater. Chem. A 3, 8926 (2015).
Characteristic of Resistive Switching Device Using Mesoporous Carbon-Silica-Titania Nanocomposite
Authors: Jung Hunsang , Kim Yo-Han , Lee Hyun Ho 
Published: February 2020

Resistive switching device using mesoporous carbon-silica-titania (m-CST) nanocomposite as active layer is demonstrated in simple structure of metal-mesoporous nanocomposite-metal. In this study, we try to fabrication method by soft-templating, which is simple technology to make mesostructure by reacting oligomeric resol, block copolymer surfactant and silicate source. Nanocomposite layer of mesostructure is formed by using sol-gel process with spin-coating. During the evaporation induced self-assembly (EISA) process, the solution of nanocomposite becomes more concentrated until the critical micelle concentration is reached. A well ordered mesostructure nanocomposite layer is formed through annealing process. For device structure, platinum (Pt) deposited silicon oxide wafer substrate was used as the bottom electrode. Top electrode of aluminium (Al) was deposited by thermal evaporation process. The current-voltage (I-V) characteristic showed analog-type resistive switching property, that the current is gradually changed depending on the sweep voltage and sweep directions, and threshold voltage shifts depending on the control voltage. Also, learning ability of potentiation and depression characteristic of the device is tested by Semiconductor Parameter Analyzer and pulse generator. The mesoporous nanocomposite property is analyzed with FT-IR and FE-SEM with EDS.
(Invited) Challenges in Ultra-Small Device Manufacture
Authors: Morris Michael anthony 
Published: February 2020

As semiconductor devices become smaller and approach the limits of conventional photolithography, achieving high quality pattern transfer becomes ever more challenging and expensive. Non-conventional lithographies may realize feature size below 10 nm but the etch challenges are not addressed. Here we examine how block copolymer lithography can be used to address both scaling and pattern transfer. In block copolymer (BCP) lithography, BCPs on a surface can self-assemble into regular arrangements for creation of ordered arrays on holes and line spacing. Recently we have extended these techniques to selectively include hard mask type materials into the polymer pattern. These then form an inorganic pattern of the same polymer structure and allow high contrast pattern transfer to a variety of substrates. Typical examples from the work are shown in Figure 1. We illustrate this work by hard masks based on NO, W and Zn and demonstrate device functionality using electrical characterization.
However, no matter how advanced this form of lithography becomes, grand challenges remain in scaling. The biggest of these is layer-to-layer registry or overlay of features. In this work, we extend our methodology to develop a form of selective area deposition. Selective deposition, if successful, could remove a number a key lithographic steps and lower fabrication costs. We use a methodology that combines etch techniques to enhance surface chemical contrast and so facilitate selective deposition. Recent results that allow direct deposition of dielectric deposition are provided.

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The Synergetic Catalytic Effect of Molten Gallium in the Presence of Hydrogen and Nitrogen Plasmas: Study and Applications
Authors: Jaramillo-Cabanzo Daniel Felipe , Carreon Maria , Chaudhuri Indira , Menon Madhu , Sunkara Mahendra Kumar 
Published: February 2020

The synergetic effect of plasma and a metal catalyst is rising as an alternative to synthesize a great variety of materials - from gases to nanomaterials - that take place under highly energy consuming reactions. More specifically, this study will have an impact in the growth of silicon nanowires (Si NWs) as anodes for Li-ion batteries and the production of bulk gallium nitride. Our group has been able to synthesize Si NWs at temperatures as low as 200 C and in recent efforts we have been able to grow densely packed Si NWs (d∽20 nm) uniformly on stainless steel with areas as big as 1.5 x 5 cm. Highly oriented GaN flakes (as big as 1.25 cm x 1.25 cm) were also synthesized on quartz substrates using a plasma assisted catalytic method. The X-ray diffraction spectrum of the GaN film shows only (0002) and (0004) planes of wurtzite GaN, indicating good c-plane orientation. We have demonstrated a basic concept in which crystals self-orient with respect to each other if the growth takes place on molten gallium due to the enhanced rotational and translational mobility.

To gain insights into these mechanisms we have studied the interaction of hydrogen and nitrogen plasmas with low melting point metals, primarily with gallium. Absorption/desorption experiments as well as theoretical-computational calculations were performed. Experiments have shown an increment of adsorbed gaseous species into the molten metal in the presence of plasmas; furthermore, Density Functional Theory (DFT) calculations suggest a strong interaction between atomic hydrogen and molten gallium that is described as a high absorption on the surface, rapid diffusion and a steady state concentration of the gas inside the bulk.

Recent results suggest that the synergetic effect of molten gallium in the presence of hydrogen/nitrogen plasmas could have a transformational impact in the way energy-intensive processes are carried out. This presentation will highlight the novel aspects of molten metal plasma catalysis, future directions and applications.

Acknowledgments

The authors acknowledge the financial support from NSF EPSCoR Grant 1355438.

References

“Plasma Catalysis: Synergistic Effects at the Nanoscale.” E. C. Neyts, K. Ostrikov, M. K. Sunkara, and A. Bogaerts. Chemical Reviews 2015 115 (24), 13408-13446 DOI: 10.1021/acs.chemrev.5b00362

‘Low Temperature Synthesis of Silicon Nanowire Arrays” M.L. Carreon, J.B. Jasinski and M.K. Sunkara. 2014 Mater. Res. Express 1 045006 DOI: http://dx.doi.org/10.1088/2053-1591/1/4/045006
Galvanic Deposition of Copper, Silver and Gold on Silicon Surfaces from Fluoride Free Aqueous Solutions
Authors: Djokić Stojan S 
Published: February 2020

Deposition of copper, silver and gold onto silicon surfaces is investigated in this work. Traditionally, direct deposition of Cu, Ag and Au onto silicon surfaces is carried out using fluoride based solutions. In the fluoride based solutions unavoidably present SiO2 at the surface of semiconductor is successfully removed and then deposition of metals such as Au or Ag proceeds via the galvanic displacement process. The results of the present work demonstrate that the direct deposition of Cu, Ag or Au onto silicon surface is very successful from fluoride-free alkaline solutions containing Cu(II), Ag(I) or Au(III) ions at pH higher than 12. The deposition of these metals does not require a reducing agent, i.e. process proceeds via galvanic displacement reactions. The approach can further be applied on any metal with the standard electrode potential more positive than that of silicon, as long as the alkaline complexes of the targeted metals are reasonably stable in the strong alkaline electrolytes with pH more than 12.
Shape Transition and Growth of CoxFe(1-x) Alloy Nanocrystals By Electrochemical Deposition
Authors: Park Kimoon , Yoon Sanghwa , Yoo Bongyoung 
Published: February 2020

Nanocrystals were interesting materials for applications such as photocatalyst, biocatalyst, solar cells, sensors, lithium batteries, magnetic resonance imaging, water splitting, and etc. These properties were dependent on their shape and composition. Therefore, researches of the nanocrystal synthesis, shape and composition control have been significantly important.
Nanocrystals were prepared by chemical vapor deposition, hydrothermal methods, sol-gel techniques, spraying methods, and electrochemical synthesis methods. Among the these methods, electrochemical synthesis was great method since this method has advantages that simple process, low cost, low synthesis temperature, selective decoration on conductive substrates, various materials synthesis such as metal, semiconductor, and oxides. In addition to this, the nanocrystals were easily tuned by changing synthesis conditions, electrolyte concentration, pH, applied potential, and addictives.
The CoFe alloys were well known at magnetic materials due to their high magnetic saturation and show potential for the magnetic application. Despite the advantages of electrochemical synthesis methods, studies of the nanocrystal growth were restricted for mainly noble metals1 and oxides2. There were few studies of synthesis of the alloy nanocrystals, PtNi, PtFe, PtCo, and etc.3Therefore, studies of the alloy nanocrystal synthesis were still required.
In this research, The CoxFe1-x nanocrystals were synthesized by electrochemical synthesis method at various synthesis conditions such as applied potential, charge density, and electrolyte concentration. These nanocrystals were characterized by scanning electron microscopy, energy dispersive spectroscopy, and transmission electron microscopy. From the SEM images, there was shape transition from non-cube to cube shape when applied potential was increased. This shape transition was caused by composition change. The Co-rich CoxFe1-x nanocrystals show non-cube, which was nearly spherical, shape, while the 1:1 CoFe and the Fe-rich CoxFe1-xnanocrystals show cube shape. In addition to this, particle reduction phenomenon was observed as potential increased. This phenomenon was different with electrochemical deposition behavior that nucleation density was exponentially dependent on the potentials.
References
1. Y. Chen, S. Chen, Z. Zhou, N. Tian, Y. Jiang, S. Sun, Y. Ding, and Z. Wang, Science, 316, 732 (2007).
2. S. Yoon, S. Kim, S. Choi, J. Lim, and B. Yoo, Cryst. Growth Des., 15, 4969 (2015).
3. J. Wu, L. Qi, H. You, A. Gross, J. Li, and H. Yang, J. Am. Chem. Soc., 134, 11880 (2012).

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Examining Electrical Properties of Solid Electrolyte Interface on Silicon Electrodes
Authors: Ban Chunmei , Son Seoung-Bum , Hurst Katherine , Jiang Chunsheng 
Published: February 2020

The complex surface reactions contribute to the formation of solid-electrolyte interphases (SEI), and cause the irreversible capacity loss of silicon (Si) electrodes. The chemical and mechanical instability of the interphases finally leads to performance degradation. A microscopic characterization of the electrical properties at the interface is expected to gain information to understand the physical and chemical evolution caused by the formation of SEI, and provide the guidance for improvements in performance.
The microscopic electrical characterization techniques, including Kelvin probe force microscopy (KPFM) and scanning spreading resistance microscopy (SSRM), have been applied to silicon electrodes. The nanoelectrical probes have been developed in one atomic force microscopy (AFM)-based platform, and the complementary electrical characterizations can be performed on the same sample area in nm-scale. Based on the contact potential difference method, KPFM maps the work function (WF) on electrode surfaces, which is expected to largely change with lithiation and delithiation. WF is sensitive to Li-ion distribution and diffusion, which can be highly inhomogeneous in nm-scale and can be assessed and evaluated from the KPFM mapping. Local conductivity/resistivity of Li-ion electrodes has been studied by SSRM. Based on the contact mode of AFM, SSRM maps of local resistivity in 10-nm resolutions have been acquired by applying a voltage between the probe and a sample and measuring the current through the probe. Ex-situ measurements along the Lithiation/delithiation process have been performed to understand the formation of SEI and the impact of electrochemical reaction on the electrical properties of SEI. Figure 1 shows the SSRM resistance changes before and after lithiation of Si electrode. The inhomogeneity with grain and domain sizes of 200-500 nm is observed at the surface of Si electrode.
Surface modification by using atomic layer deposition and molecular layer deposition has also been used to modify the surface chemistry of silicon electrodes. This presentation will discuss the evolution in nm-scale resistance of SEI during electrochemical reactions, and the impact of surface coating materials on the electrical properties of SEI.

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New Insight in Understanding the Evolution Mechanism of Li2o2 in Li-O2 Batteries: An operando Synchrotron X-Ray Diffraction Study
Authors: Liu Chenjuan , Brant William Robert , Younesi Reza , Edström Kristina , Gustafsson Torbjörn , Zhu Jiefang 
Published: February 2020

Non-aqueous Li-air (Li-O2) batteries have been emerging as one of the most promising high-energy storage systems, e.g., to meet the requirements for electric vehicle applications, owing to their high theoretical energy density (3505 Wh kg-1 for Li/Li2O2 cells). One of the major challenges to develop high-performance Li-O2 battery is to understand the mechanism how Li2O2 is formed and decomposed during battery cycling. Although many cathode catalysts have proven to be effective to ORR/OER in Li-O2 batteries, little is known on such reversibility at fundamental level at present. Different from Li-ion batteries, the rechargebility cannot be easily determined by Coulombic efficiency in Li-O2 batteries because of extensive parasitic chemistry/electrochemistry. In most of the studies, the evaluations of Li-O2 battery rechargebility have been based on galvanostatic charge-discharge measurements, for which many Coulombic cycles are possible, and each cycle is possibly dominated by solvent decomposition1-3. Consequently, it is impossible to accurately judge the rechargeability of the system without any quantitative evidence to show which kind of and how much electrochemical reactions contribute to discharge or charge stage. Accurate quantification of the amount of Li2O2 that forms and decomposes in each cycle is a direct and simple way to determine the rechargebility of a Li-O2 battery. In this study, we have investigated this important fundamental issue by operando synchrotron X-ray diffraction. We modified the previous operando cell design, to achieve quantitative tracking of Li2O2 during both discharge (ORR) and charge (OER) in a binder-free CNT electrode. We present, for the first time, an approach that combines ex situ spectroscopic analysis and state-of-the-art operando X-ray diffraction with the ability of tracking real-time Li2O2 evaluation, as a means to better understanding of the mechanisms underlying electrochemical reactions. The evolutions of Li2O2 formation and decomposition related to its morphology and structure were observed under the actual electrochemical conditions in real time. Our operando X-ray diffraction results also reveal a two-step growth of Li2O2 on ORR and also a two-step oxidation of Li2O2 on OER, which can be associated with the different mechanisms on forming and decomposing Li2O2.

Reference
1. W. Xu, K. Xu, V. V. Viswanathan, S. A. Towne, J. S. Hardy, J. Xiao, Z. Nie, D. Hu, D. Wang and J.-G. Zhang, J Power Sources, 2011, 196, 9631-9639.
2. S. A. Freunberger, Y. Chen, Z. Peng, J. M. Griffin, L. J. Hardwick, F. Barde, P. Novak and P. G. Bruce, J Am Chem Soc, 2011, 133, 8040-8047.
3. F. Mizuno, S. Nakanishi, Y. Kotani, S. Yokoishi and H. Iba, Electrochem Commun, 2010, 78, 3.