bluuebunny/crossref_metadata_2025 huggingface dataset:
Etch Characteristics of Cu Thin Film Using Inductively Coupled Plasma of Non-Greenhouse Gases
Authors: Lim Eun Taek , Choi Jae Sang , Lee Seung Hwa , Ryu Jin Su , Chung Chee Won
Published: February 2020

This study is to analyze the etch characteristic of line-patterned Cu flims under various etch conditions using non-halogen gases. The etching of Cu films has great difficulty due to very low volitility of Cu compounds formed by the reaction with conventional etch gases. Because of this fact, Cu patterining has been achieved by the damascene process containing thin film deposition and chemical mechanical processing. Although many researches were carried out since 1990s, no remarkable progress has been made. As the dimension of Cu pattern has been shrinked, the etching process of Cu films has become the main issue because the damascene process reveals fatal disadvantages. In this study, inductively coupled plasma reactive ion etching (ICPRIE) of Cu film was performed using non-greenhouse gases. Gas mixtures containing Cl2/Ar, HCl/Ar, HBr/Ar, O2/Ar, and H2/Ar were used to etch Cu thin films. In addition, the influences of the gas concentration, ICP power, gas pressure and dc- bias to substrate on each characteristic were investigated. The etch profiles and etch mechanism of Cu films were examined by field emission scanning electron microscopy, optical emission spectroscopy, and X-ray photoelectron spectroscopy, respectively.

Acknowldgments This research was supported by the MOTIE(Ministry of Trade, Industry & Energy (10080450) and KSRC(Korea Semiconductor Research Consortium) support program for the development of the future semiconductor device.
On the Electrochemical Properties of New Materials in the Li2o-Fe2O3-V2O5 Ternary System
Authors: Benabed Yasmine , Pelé Vincent , Castro Laurent , Penin Nicolas , Carlier Dany , Wattiaux Alain , Duttine Mathieu , Darriet Jacques , Dollé Mickael
Published: February 2020

In order to discover innovative electrode and electrolyte battery materials responding to specific needs in terms of capacity, working voltage, polarisation, alkali insertion mechanisms, it appears interesting to explore various insertion chemistries. With this in mind, our study was dedicated on the structural properties and electrochemical performances of iron vanadates positive electrode for Li batteries. More specifically, our groups focussed on the search for new stable phases in the Li2O - Fe2O3 - V2O5 ternary system with respect to several vanadates (FeVO4, NaCuFe2(VO4)3, β-Cu3Fe4(VO4)6, …), which structural and electrochemical properties upon Li insertion have been highlighted in previous work [1].

Among the Li2O - Fe2O3 - V2O5 system, this presentation is dedicated to two new compounds, which were not known from the literature. Both materials were obtained through solid synthesis routes, after optimising the annealing parameters to reach pure phases. After determination of the structure using single crystal X-Ray Diffraction, their physical and electrochemical properties were thoroughly characterized using SEM, Mossbauer spectroscopy, galvanostatic and potentiostatic cycling. Electrochemical characterizations in half cells resulted in finding the optimal voltage window to enhance the capacity retention of the material as compared to previously studied vanadates. The galvanostatic curves indicated complex mechanisms for both materials involving several monophasic and biphasic steps upon Li insertion (see figure for the structure of LiFeV2O7 viewed along the [-101] direction and its electrochemical curve in half cell). Mossbauer spectroscopy allows assessing the oxidation state of iron atoms in the structures before and upon the electrochemical processes.

[1] Patoux, S., Richardson, T.J. “Lithium insertion chemistry of some iron vanadates”, Electrochemistry Communications, 9 (3), pp. 485-491 (2007).

[2] Benabed, Y., Castro, L., Penin, N., Darriet, J., Dollé, M. “Synthesis, Structure, and Electrochemical Properties of LiFeV2O7”, Chemistry of Materials, 29 (21), pp. 9292-9299 (2017).

Figure 1
Electrochemical Aspects of Copper Atmospheric Corrosion in Saline Environments
Authors: Schindelholz Eric John , Cong Hongbo , Jove-colon Carlos , Li Shengxi , Ohlhausen James , Moffat Harry K
Published: February 2020

In this study we examine the evolving state of electrolyte and corrosion processes associated with sodium chloride on copper at the initial stage of corrosion and the critical implications of this behavior on controlling kinetics and damage distributions. Sodium chloride droplets were placed on copper in humid conditions and the resulting electrolyte properties, corrosion products and damage were characterized over time using time-lapse imaging, micro Raman spectroscopy, TOF-SIMS and optical profilometry. Within minutes of NaCl droplet placement, NaOH-rich films resultant from oxygen reduction advanced stepwise from the droplets, leaving behind concentric trenching attack patterns suggestive of moving anode-cathode pairs at the alkaline film front. Corrosion attack under these spreading alkaline films was up to 10x greater than under the original NaCl drops. Furthermore, solid Cu2Cl(OH)3 shells formed over the surface of the NaCl drops within hours of exposure. Thermodynamic modeling along with immersed electrochemical experiments in simulated droplet and film electrolytes were used to rationalize this behavior and build a description of the rapidly evolving corroding system.
(Invited) Alumina Nanotubes Formed By Anodization of Aluminum Cast Alloy
Authors: Ono Sachiko , Hashimoto Hideki , Asoh Hidetaka
Published: February 2020

Anodic porous alumina film, a typical self-ordered nanohole material formed by anodizing aluminum in an appropriate acidic solution, is used as a starting material of nanofabrication of functional devices besides a corrosion resistant surface oxide. In contrast to anodic titania nanotubes, anodic porous alumina is generally compact without spacing between the cell boundary. The tubular shape of anodic titania is suggested to be resulted in enrichment of fluoride between cells which is originated from electrolyte and more soluble than anodic titania. In the case of aluminum, it is reported that enrichment of only sulfate or ethylene glycol from electrolytes produces alumina nanotubes by anodization. In the present paper, the formation mechanisms of alumina nanotubes by anodization of Al cast alloy caused except the electrolyte origin will be discussed.

STEM image of vertical cross section prepared by ion-milling of the anodic film, which was formed on 99.99 % pure aluminum in oxalic acid at 160V, indicated close-packed hexagonal cell arrays with small voids of 15-20 nm at the triple cell points. Dark field STEM image clearly revealed a bright particle in the each void suggesting the presence of a heavy metal because of Z-contrast. By EDX point analysis, Cu enriched particles were found in the voids at the triple cell points. Nevertheless, in the case of anodic film formed at the similar condition on AC8A cast alloy including 0.97 % of Cu, tubular cells with the space of approximately 50 nm between cell boundary were formed unlike the case of pure aluminum including 60 ppm of Cu. Numerous branching of pores were also observed. EDX mapping revealed that Si was enriched in the outer layer of the cells and Cu was enriched at the area near the cell boundaries. Therefore, it is deduced that enrichment of Cu at the cell boundaries produces the tubular cells by accelerating oxide dissolution in addition to the electric breakdown accompanied by severe gas evolution that resulted in void formation at the triple cell points.
(Invited) Structural Properties and Carrier Transport in Axial Silicon-Germanium Nanowire Heterojunctions
Authors: Tsybeskov Leonid , Wang Xiaolu , Kamins Theodore I , Wu Xiaohua , Lockwood David J.
Published: February 2020

Recent advances in forming semiconductor heterojunctions within spatially confined nanoscale objects, including nanowires (NWs), show that the traditional limitations in the lattice-mismatched hetero-growth can be challenged. In various III-V semiconductor NWs, abrupt heterojunctions have been successfully demonstrated using the vapor-liquid-solid (VLS) growth for GaAs/InAs (7% mismatch) and InAs/InP (3% mismatch) heterojunctions. In group IV semiconductors, the approach is complicated not only by the 4.2% lattice mismatch between Si and Ge but also because Si and Ge both have a quite high solubility in the Au-Si catalyst. During chemical vapor deposition (CVD) based VLS growth using SiH4 and GeH4 (or similar gases), a supply of Si remains effectively “on” in the catalyst, and Si effectively intermixes with the arriving Ge even if the SiH4 flow is already switched “off”. One way to address this problem is to choose a catalyst with a lower Si solubility, e.g. AlAu2 and AgAu. Another possibility is to significantly reduce growth temperature before turning a GeH4 source “on”. Using the latter technique, we fabricated Si-Ge heterojunction NWs with nearly ideal interface and only an 8 nm thick SiGe transition layer between straight and nearly micron-long Si and Ge NW segments and analyzed their structural and electrical properties. The observed changes in the photoluminescence and Raman spectra as function of temperature, non-linear and rectifying current-voltage characteristics, strong flicker noise and damped current oscillations with frequencies of 20-30 MHz are explained using the proposed SiGe heterojunction NW energy band diagram including the energy states associated with the NW surface (and near-surface) structural imperfections revealed by transmission electron microscopy and a mismatch in Si and Ge coefficients of thermal expansion.
(Invited) Overview of Titania Nanotubes for Li-Ion Microbatteries
Authors: Djenizian Thierry
Published: February 2020

Lithium-ion batteries (LIBs) are widely used to power portable devices, microelectronics, vehicles, etc. With many advantages such as high surface area and improved charge transport, self-supported 3-D nanostructured metal oxides such as titania nanotubes (TiO2nts) are promising electrode materials for LIBs and their impact is particularly significant when considering the miniaturization of energy storage systems and the development of 3D microbatteries.

This talk will review the concept and fabrication of all-solid-state Li-ion microbatteries using TiO2nts based based electrodes [1-7]. Effects of material selection and processing on the performance and reliability are presented as a means to develop conceptual guidelines to understand and improve microbattery designs. Fundamentals such as electrode reactions, lithium ion diffusion and the conformal electrodeposition mechanism of polymer electrolytes onto the nanostructured electrodes will be presented. The fabrication of a full 3D microcells showing high electrochemical performance will be presented and the development of the next generation of 3D FLEXIBLE microbatteries will be discussed.

REFERENCES

[1] B.L. Ellis, P. Knauth, T. Djenizian, Adv. Mater., 2014, 26, 3368.

[2] N. Plylahan, M. Letiche, M. Barr, T. Djenizian, Electrochem. Commun., 2014, 43, 121.

[3] N. Plylahan, A. Demoulin, C. Lebouin, P. Knauth, T. Djenizian, RSC Adv., 2015, 5, 28474.

[4] N. Plylahan, M. Letiche, M. Barr, B. Ellis, S. Maria, T. N. T. Phan, E. Bloch, P. Knauth, T. Djenizian,

J. Power Sources, 2015, 273, 1182.

[5] G. Salian, C. Lebouin, A. Demoulin, S. Maria, P. Knauth, M. Lepihin, A. Galeyeva, A. Kurbatov,

T. Djenizian, J. Power Sources, 2017, 340, 242.

[6] I. V. Ferrari, M. Braglia, T. Djenizian, P. Knauth, J. Power Sources, 2017, 353, 95.

[7] G. Salian, B. M. Koo, C. Lefevre, T. Cottineau, C. Lebouin, A. T. Tesfaye, P. Knauth, V. Keller,

T. Djenizian, Adv. Mater. Technol., DOI: 10.1002/admt.201700274, 2018.
Hard Porous Alumina Coatings Via Etidronic Acid Anodizing
Authors: Kikuchi Tatsuya , Takenaga Akimasa , Natsui Shungo , Suzuki Ryosuke O.
Published: February 2020

Anodizing aluminum is very important for protecting the aluminum substrate, and anodizing in a sulfuric acid solution at low temperature causes the formation of hard porous alumina with a high Vickers hardness of more than Hv = 300. However, harder porous alumina is required to expand the applicability of porous alumina in various industrial applications. In the present investigation, we fabricated a hard porous alumina by aluminum anodizing in a new electrolyte, etidronic acid (1-hydroxyethane-1,1-diphosphonic acid, C2H8O7P2).

Highly pure aluminum plates (99.999 wt%) were electropolished in a 78 vol% CH3COOH/22 vol% 70%-HClO4 solution. The electropolished specimens were immersed in a 0.05–1.0 M etidronic acid solution (150 mL) at 278–308 K and then anodized at a constant voltage of 260 V or a constant-current density of 2.5–50 Am−
2 for up to 64 h. Two-step constant-voltage anodizing was also carried out for the fabrication of highly ordered porous alumina.

The electropolished specimens were anodized in etidronic acid solutions with various concentrations at various temperatures under the maximum current density condition without oxide burning. Figure 1 shows the changes in the Vickers hardness of the porous alumina, Hv, with changing concentration of the etidronic acid solution, c, at T
a = 278–308 K and i
a = 5–40 Am−2. Here, the thickness was adjusted to approximately 55 µm in each anodized specimen. The Vickers hardness decreased with increasing solution temperature for all concentrations. In addition, the Vickers hardness also decreased with increasing concentration at each solution temperature. This decrease is due to the chemical dissolution of porous alumina during anodizing. A hard porous alumina film measuring Hv = 610 can be fabricated by anodizing in a 0.05 M etidronic acid solution at 278 K and 5 Am−2.

Figure 1
Mechanism of Electrochemical Corrosion of Cathodicallypolarized Silicone-Epoxy Coating on Mild Steel
Authors: Yuan Xin
Published: February 2020

Using electrochemical impedance spectroscopy (EIS), the analysis of impedance models and water uptake of silicone-epoxy coating for samples subjected to various levels of cathodic protection (CP) were studied during coating aging process in 5 wt.％ NaCl aqueous solution. The results show CP is supposed to protect mild steel from corrosion for samples during coating degradation process since there is a cathodic current and the mild steel surface is polarized cathodically, no corrosion is expected to take place and no corrosion product is expected to accumulate at the interface. Two distinguishing impedance models are found to fit the spectroscopy of the sample with CP. The coating systems under CP have a smaller water diffusion coefficient, and the water diffusion coefficient increases with the increasing of the cathodic potential. A further water uptake process after the saturation period is presented.

Figure 1
Developing Biocompatible Coatings for Mg Alloys to Control the Biocorrosion Behavior
Authors: Virtanen Sannakaisa
Published: February 2020

Magnesium and its alloys are promising materials for biodegradable implant applications. However, the degradation rate in the biological environment should be adjusted for the specific application, to match the healing behavior of the surrounding tissue. For the control of corrosion, research has targeted development of new alloys as well as coatings and surface modification of Mg. This presentation will discuss challenges in developing suitable coatings for Mg for biomedical applications. The requirements for such coatings are multifunctional, in that the coatings should be biocompatible, biodegradable and optionally in addition bioactive. Different approaches to fulfill these goals have been explored, such as coatings based on biodegradable synthetic or natural biopolymers. The presentation will describe methods to successfully coat highly reactive Mg alloy surface in aqueous solutions, based on developing suitable pre-treatments of the surface. Immersion testing and electrochemical experiments revealed information on the corrosion protection properties of the coatings as well as on the time-dependent degradation of the coatings. Influence of the electrolyte composition on the performance of the coatings was studied, including the effect of proteins on the corrosion behavior. The exact composition of the type of simulated body solution as well as addition of proteins can very strongly influence the corrosion behavior. The effects are highly complex in that for instance proteins show a time-dependent and strongly system-dependent influence on the corrosion rate.
Corrosion Behavior of Aluminum Alloys Deposited from Ionic Liquids
Authors: Böttcher René , Ispas Adriana , Bund Andreas
Published: February 2020

Aluminum and its alloys have a wide range of applications due to their excellent properties, such as low density and high corrosion resistance. The electrochemical deposition of Al-based materials is not possible from aqueous solutions due to their rather negative Nernst potential (-1,66 V vs. SHE). There are few industrial processes for plating of aluminum, e.g. the SIGAL process. However, those processes usually are based on expensive, highly flammable and/or volatile substances, leading to high requirements regarding the technical equipment.

The deposition from ionic liquids (ILs) opens new possibilities for industrial processes. The ILs have large electrochemical windows (> 3 V) and permit high solubility for metal salts, allowing the electrochemical deposition of base metals, like aluminum, and a considerable number of its alloys. Furthermore, there is no hydrogen embrittlement of steel substrates in ILs due to their aprotic character, and the deposition of Al-based films is possible at room temperature.

Al-based materials are promising candidates for corrosion protection of steel and could replace environmentally harmful coatings, such as cadmium. ILs are still quite expensive, but their price continuously decreased during the last years, making an industrial process more interesting.

This paper will discuss recent results from the authors’ lab on the deposition of aluminum alloys from imidazolium based ILs. Binary alloys of aluminum with Zn, Sn and Cr were deposited and investigated. The deposition process regarding precursor concentration, process parameters, properties of the deposits (composition, structure, morphology) and corrosion behaviour in aqueous sodium chloride solution will be discussed. Furthermore, it will be shown that the pre-treatment of the used steel substrates plays a crucial role to obtain well adhering layers.
Characterization of Chromium Deposition from Trivalent Solutions By Eqcm and Near-Surface pH Measurements
Authors: Leimbach Martin , Tschaar Christoph , Schmidt Udo , Bund Andreas
Published: February 2020

The demand for alternatives for chromic acid based electrolytes in chromium electroplating increases rapidly as the use of hexavalent chromium is restricted in serval countries [1]. In chromium plating for decorative applications, electrolyte formulations based on trivalent chromium are already known since several decades [2]. Especially solutions of chromium(III)-sulfate are promising candidates considering process management and quality of the deposits [3, 4]. However, chromium coatings plated from commercial chromium(III)-electrolytes cannot meet the requirements for decorative purposes completely yet. Especially deposition rate, corrosion resistance and color come short compared to layers made from chromic acid baths. In order to control these parameters, a profound knowledge of the deposition mechanism is crucial.

Electrochemical quartz crystal microbalance (EQCM) was used to study the mass-charge balance of the cathodic processes in chromium(III)-sulfate based plating baths. Current efficiency and deposition rate were determined as a function of time, additive concentration and current density. The addition of benzoic sulfimide (BSI) facilitates the reduction to chromium metal. An optimum current efficiency of 8.1 % was observed at 2.5 A dm-2 [5]. pH changes near the cathode surface during electroplating were evaluated in-situ by combining a pH electrode with a metal mesh and correlated with the results obtained by EQCM. Furthermore, the dependence of the color of the deposits on surface morphology was observed by SEM, AFM and colorimetry. The mechanism of metal growth appears to be different from chromic acid based systems since the grain size of the chromium depends on layer thickness.

[1] ECHA: Authorisation list, EC no. 215-607-8.

[2] Gianelos, L.: Plat Surf Finish
66 (1979) 5, 56-60.

[3] Handy, S. L.; Oduoza, C. F.; Pearson, T.: Trans IMF
84 (2006) 6, 300-308.

[4] Katirci, R.: Surf Eng
31 (2015) 6, 465-471.

[5] Leimbach, M.; Tschaar, C.; Schmidt, U.; Bund, A.: Electrochim Acta
270C (2018), 104-109.
Analysis of Electrochemical Noise in Titanium Alloys Used in Aeronautics
Authors: Almeraya Facundo , Tovar Serna Arelly , Tiburcio Citlalli Gaona , Zambrano Patricia , Estupiñan-Lopez Francisco , Cabral José Angel , Baltazar-Zamora Miguel Angel
Published: February 2020

Corrosion is an essential factor to consider when designing and manufacturing a metallic component. In aeronautical industry is not the exception, especially because there are many types of corrosion that can affect different elements of aircrafts. Analysis is a way to determine the behavior of the material selected to decide if it's the appropriated to the purpose. This project is focused in electrochemical noise, which is a technique that measures oscillations in potential and electrochemical current of a material exposed in different solutions that represent the environment. In this case, the alloy Ti-6Al-4V composed by 90% titanium (Ti), 6% aluminum, and 4% vanadium (4V), will be studied under diverse conditions. In this research the corrosion behavior of Titanium alloys is studied by means of the electrochemical noise technique, using 2048 data per sec. The materials were evaluated in the presence of 3 different electrolytes: (water), NaCl (sodium chloride) and (sulfuric acid) at 25ºC and 3.5% of concentration. The results indicate that the behavior of the time series does not have transients of high frequency and amplitude and with the localization index the type of corrosion is generalized.
The Role of Pitting at Mns Inclusions in Intergranular Corrosion of Sensitized Type 304 Stainless Steel in NaCl Solution
Authors: Ida Noriyuki , Muto Izumi , Sugawara Yu , Hara Nobuyoshi
Published: February 2020

The degree of sensitization and susceptibility of intergranular corrosion of austenitic stainless steels are properly evaluated from immersion testing in acidic solutions as rapid screening methods. However, most of stainless steels are used in near-neutral pH environments, and the typical corrosion morphology in these environments is pitting. Acidification is known to occur inside pits due to the hydrolysis reaction of dissolving metal ions. Under practical service conditions around neutral pH such as seawater and river water, pitting is assumed to be closely related to the initiation of intergranular corrosion.

It is well-known that non-metallic inclusions, such as MnS, act as the initiation sites for pitting of stainless steels. Chiba et al. demonstrated that a small inclusion-free area on Type 304 indicated superior pitting corrosion resistance even in 3 M NaCl. 1) It would appear that MnS inclusions strongly affect pitting and intergranular corrosion of sensitized stainless steels.

To clarify the role of pitting at MnS inclusions in intergranular corrosion of sensitized Type 304 stainless steel (sensitized at 923 K), in situ observations were carried out during micro-scale anodic polarization in 1 M NaCl (pH 5.4). Micro-scale potentiodynamic anodic polarization was performed for a small area with a MnS inclusion at a sensitized grain boundary. Intergranular corrosion was initiated from the pit that was generated at the MnS inclusion located at the sensitized grain boundary. Acidification inside the pit probably caused intergranular corrosion due to the transition from passive to active state.

In 1 M NaCl, the depassivation pH values at the sensitized grain boundary with and without MnS inclusions were 1.0 and 0.4, respectively. It is likely that the dissolution of MnS accelerates the depassivation and promote the initiation pf intergranular corrosion. The dissolution products from MnS are supposed to accelerate depassivation of Cr-depleted regions.

1) A. Chiba, I. Muto, Y. Sugawara, N. Hara, J. Electrochem. Soc., 160, C511-C520 (2013).
Liquid-Phase Ion Gun for Local Acidification of Na2s Aqueous Solution and Local Sulfidation of Steel Surface
Authors: Fushimi Koji , Nakatsuji Satoshi , Kitagawa Yuichi , Nakanishi Takayuki , Hasegawa Yasuchika
Published: February 2020

Local sulfidation of steel surfaces was attempted by using a liquid-phase ion gun (LPIG), in which a platinum microelectrode was anodically polarized in the vicinity of the steel surface in 0.1 mol dm–3 sodium sulfate aqueous solution. An increase in proton concentration, namely local acidification, of the solution in the narrow space between the microelectrode and steel surface successfully induced the formation of an hydrogen sulfide-concentrated environment and resulted in local sulfidation of the steel surface. The degree of sulfidation was dependent on acidification conditions such as the inter-electrode distance, micro-electrode current, specimen electrode potential and composition of steel. The use of an LPIG enables a sulfidation test not only to restrict the amount of hydrogen sulfide generated but also to evaluate sulfidation of a material surface quantitatively.
Stress-Corrosion Behavior of Nickel Titanium Shape Memory Alloy Under Quasi-Static Loading
Authors: Mohajeri Mahdi , Haghgouyan Behrouz , Castaneda Homero , Lagoudas Dimitris
Published: February 2020

Nickel titanium (NiTi) shape memory alloys (SMAs) are well known for their significant shape recovery under thermomechanical loading [1]. Austenitic SMA can recover its original shape upon unloading (pseudoelasticity) while martensitic SMA can do so after subsequent heating (shape memory effect). Understanding the corrosion behavior of NiTi SMAs is important for extending their successful applications. Studying the corrosion of SMAs is challenging due to the inherent complexity of their constitutive response together with the presence of different phases (austenite or martensite) and microstructural states (twinned or detwinned) [2].

In this study, the corrosion behavior of equiatomic NiTi under quasi-static loading in the plastic deformation regime is studied in artificial physiological solution at room temperature. Elelctrochemcial Frequencies Modulation (EFM) technique is used the parameters of which has been found in a previous study by the authors [3]. The corrosion parameters of NiTi are measured at different load levels during plastic deformation where the passive breakdown occurs. Strain distribution on the surface of the plastically deforming NiTi sample corresponding to these load levels is captured by means of Digital Image Correlation (DIC) technique [4]. Metal loss is measured using Faraday’s law and Open Circuit Potential (OCP) measurements show that the repassivation of oxide layer is not taken place. The findings are considered a step towards better understanding of the corrosion behavior of SMAs under thermo-mechanical loading.

References

[1] Lagoudas, D.C. ed., 2008. Shape memory alloys: modeling and engineering applications. Springer Science & Business Media.

[2] Mohajeri, M., Haghgouyan, B., Castaneda, H. and Lagoudas, D.C., 2018. Nickel Titanium Alloy failure analysis under thermal cycling and mechanical Loading: A Preliminary Study. arXiv preprint arXiv:1803.01110.

[3] Mohajeri, M., Castaneda, H. and Lagoudas, D.C., 2018, March. Corrosion monitoring of NiTi alloy with small-amplitude potential intermodulation technique. In Behavior and Mechanics of Multifunctional Materials and Composites XII (Vol. 10596, p. 1059616). International Society for Optics and Photonics.

[4] Haghgouyan, B., Shafaghi, N., Aydıner, C.C. and Anlas, G., 2016. Experimental and computational investigation of the effect of phase transformation on fracture parameters of an SMA. Smart Materials and Structures, 25(7), p.075010.
Anodic Current Density of Aluminum Oxide Film in Situ during Anodization of Aluminum by Fabry-Pérot Interferometry
Authors: Habib Khaled
Published: February 2020

A combination of Fabry-Pérot interferometry and the DC electrochemical method have been used for the first time, in situ, to measure the anodic current density of aluminium oxide films in 0,6, and 10% sulfuric acid solutions (H2SO4). The calculated values of the anodic current density by Fabry-Pérot interferometry were verified by the DC electrochemical method and the electrochemical impedance spectroscopy (EIS). The corresponding thickness of the aluminum oxide film to the anodic current density was determined by Fabry-Pérot interferometry under a potentiolstatic potential of 9 V with respect to the open circuit potential of the aluminum samples in the H2SO4 solutions, for 90 minutes. The obtained thickness of the aluminum samples by Fabry-Pérot interferometry was verified by sanning electron microscopy(SEM) and compared to values that were obtained by the EIS. The calculated anodic current density by Fabry-Pérot interferometry was found in ageement with those of the DC electrochemical method. In contrast, the calculated anodic current density by Fabry-Pérot interferometry was found in a slight discrebancy with data obtained by the EIS.

Keywords. Aluminium, Aluminum oxide film, Fabry-Pérot interferometry, Electrochemical impedance spectroscopy (EIS), Anodic current density, and Sulfuric acid.
An Artificial Neural Networks for Electrochemical Impedance Spectroscopy of 304 Stainless Steel in Biodiesel
Authors: Rocabruno Valdés Carolin Ivette , Gonzalez Rodriguez Jose Gonzalo , Ramon Muñoz Ledo José Antonio , Hernández José Alfredo
Published: February 2020

Biodiesel has been considered as a viable alternative fuel for transportation industry, as it demonstrated great potential in reducing the world dependence on fossil fuels and greenhouse gas emission. However, corrosion and a high susceptibility to oxidation or auto-oxidation are the main concerns associated with compatibility issues with metals and elastomers

On one hand, electrochemical impedance spectroscopy (EIS) is a powerful technique to characterize a wide variety of electrochemical systems, which allow us to evaluate the behavior at the electrode - electrolyte interface and helps in the interpretation of the corrosion mechanisms. This paper aims to develop an artificial neural network with the ability to learn from experimental values to predict EIS-Bode diagrams of 304 stainless steel in biodiesel. In this work, a feed-forward is proposed with three layers; composition of biodiesel divided in saturated, monounsaturated, and polyunsaturated methyl esters, blends biodiesel / diesel, Total acid number (TAN), exposure time, angular frequency, square root and square of angular frequency were considered as input variables on the model and the output layer contains two variables, impedance modulus and phase angle. The best fitting training data was acquired with 9-16-2 considering a Levenberg –Marquardt learning algorithm, a logarithmic sigmoid transfer function in the hidden and output layer. Experimental and simulated data were compared satisfactorily through a linear regression model with a correlation coefficient, R>0.98, mean square error, MSE < 9.13x10-4 in the validation stage and met the slope-intercept test with a confidence level of 99%. ANN model developed can be attractive to understand the synergy of the parameters and variables on corrosion behavior of metal in biodiesel besides to extract interest information related to phenomena.
(Invited) Variable Doping of MoS2 By Atomic Layer Deposition of Molybdenum Oxides of Controlled Stochiometry
Authors: Lauhon Lincoln J
Published: February 2020

Two dimensional (2D) materials are extraordinarily sensitive to their surroundings, and several schemes have been demonstrated to dope 2D semiconductors using nearby ions, molecules or compounds without introducing chemical or structural defects that would degrade charge carrier mobility. Of these, oxides are attractive due to their stability and ability to function as dielectrics or passivation layers. Molybdenum oxide in particular has been demonstrated as a dopant for multiple 2D semiconductors. A practical oxide doping scheme requires not only deposition without damage to the 2D substrate, but also quantitative control over the doping density (e.g. via oxide Fermi level), which is currently lacking. Oxide work functions are sensitive to composition in general, and particularly so for molybdenum oxides. Thus, control of oxide stoichiometry could enable precise control of the doping level in 2D semiconductors, an approach which we demonstrate here. By using a low-oxidation-state molybdenum precursor (Mo(NMe2)4) for atomic layer deposition(ALD), we demonstrate two new low-temperature ALD processes to produce a series of molybdenum oxide compositions. The MoOx optical bandgap and resistivity increase with increasing oxygen content, following the same trends as crystalline molybdenum oxides. We demonstrate controllable doping of MoS2 by depositing a MoOx overlayer and tuning the threshold voltage shift in thin film transistors (TFTs) from positive (p-type) to negative (n-type) by tuning the oxide composition. Low hysteresis in sweeps of the transistor gate voltage, the absence of strain, and reversibility upon oxide etching together suggest that this process maintains the van der Waals interface without significant chemical changes, and should thus be generally applicable as a doping strategy for 2D systems. Furthermore, the sequential deposition of spatially patterned ALD layers enables the fabrication of lateral p-n junction diodes.
Solution-Based Facile Fabrication of Heterojunction for Silicon Solar Cells Using Graphene Quantum Dots and PEDOT:PSS
Authors: Rongbin Xie , Noda Suguru
Published: February 2020

Silicon remains the most widely employed material in solar cell due to the low cost, lack of toxicity, and small electronic band gap for near-infrared to visible light absorption. However, up to now, one of the main limitations of silicon solar cells is their high temperature and complex manufacturing processes. Recently, silicon solar cells hybridized with material like organic, semiconductor quantum dots, have attracted a great deal of research interest owing to their promise of room-temperature manufacturing and solution processing capability. But the problems of poor mobilities and toxicity need to be solved urgently. Fortunately, zero-dimensional graphene quantum dots (GQDs) have lately intrigued intensive interest in the field of energy and optoelectronic due to the tunable bandgap, emission in a range of visible light, longer hot carrier lifetimes, chemical stability and low toxicity. In addition to the low-cost and environment-friendly properties, GQDs could act as blocking layer to facilitate the separation of photo-generated electron-hole pairs and suppress the carrier recombination, thus increase the power conversion efficiency (PCE) in solar cells.

Here in, we present a solution-based, facile fabrication of silicon heterojunction solar cells using GQDs and poly(3,4-etyhlenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS). The PEDOT:PSS/n-Si cell showed a PCE of 8.86%, and the application of GQDs to the PEDOT:PSS/n-Si interface enhanced the PCE to 10.24%. The passivation of n-Si surface by quick annealing in vacuum at 500 °C for 10 min enhanced the PCE further to 11.77%. The quick processes for heterojunction formation and surface passivation would be well suited for low-cost fabrication of solar cells based on crystalline Si thin films.
Cobalt-Iron-Manganese Electrodeposition for High Performance Magnetoelastic Resonators
Authors: Pillars Jamin R. , Langlois Eric D. , Arrington Christian L. , Monson Todd C.
Published: February 2020

Magnetostrictive Co-Fe-Mn films were investigated for their use in fabricating magnetoelastic resonators. Electrodepositing these films enables batch fabrication of resonators with varying geometries and therefore, resonant frequencies, while controlling the film stoichiometry and crystallography. Boron, phosphorous, and molybdenum were used to increase the electrical resistivity and control film texture. Additionally, ascorbic acid and TMAB were used as “oxygen scavengers” to control the chemistry’s stability and limit the oxidation of the Fe2+ to Fe3+. As suggested by Osaka et al, Fe(OH)3 is formed and included into the film resulting in a decrease of the saturation magnetic flux density (Bs) value as the Fe cation is oxidized[1,2]. Additives, such as Saccharin and Sorbitol, were added as grain refiners and stress reducers, enabling flat cantilever structures that did not bend out of plain due to intrinsic stress gradients.

The composition and phase of the deposited films were controlled by temperature, agitation, concentrations in the electrodeposition chemistry, current density, and duty cycle of the pulsing regime. The samples were analyzed with EDS to determine the composition and XRD to look at film texture. Magnetic testing was performed using super conducting quantum interference device (SQUID) magnetometry, as well as visual inspection of the displacement on a deposit stress analyzer as a magnetic field was applied to the films. The magnetostriction was then correlated to EDS and XRD results to identify phase, stoichiometry and the plating parameters to produce improved magnetostriction while maintaining low intrinsic stress. Annealing studies of these films were performed using a tube furnace with inert gas to heat past the Curie temperature and then cool in the presence of an applied magnetic field. The applied magnetic field direction and its correlation with magnetic properties and phase will be discussed.

Acknowledgement

Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.

References

Osaka, T., et al., A high moment CoFe soft magnetic thin film prepared by electrodeposition. Electrochemical and Solid State Letters, 2003. 6(4): p. C53-C55.

Elhalawaty, S., et al., Oxygen Incorporation into Electrodeposited CoFe Films: Consequences for Structure and Magnetic Properties. Journal of the Electrochemical Society, 2011. 158(11): p. D641-D646.
Electrodeposition of Iron and Iron-Based Alloys from Ethylene Glycol Non-Aqueous Solutions
Authors: Cuneo Federico , Panzeri Gabriele , Accogli Alessandra , Magagnin Luca
Published: February 2020

Iron and iron-alloys electrodeposition is considered a promising way for the fabrication of ferromagnetic thin films with tuned magnetic properties, especially for microfabrication industry [1]. Moreover, the use of iron as main component in magnets can reduce the material cost and toxicity. Film quality is highly dependent on contaminations, such as oxygen. Avoiding light-elements contaminations is nontrivial in the case of water-based solutions because of the formation of oxides/hydroxides at the working electrode due to local pH dependence, leading to poor magnetic performances. Thus, organic systems may represent a good alternative to traditional baths. Non-aqueous solutions based on ethylene glycol have been already reported for electrodeposition of iron [2], where the low chlorides content led to a compact and pure films. Several other approaches, based on DESs and Ionic Liquids, are present in literature [3], [4]. The low coercivity of ≈20 Oe showed in the previous work can thus be tailored with the addition of other metals or non-metals as alloying elements. This kind of materials are commonly obtained by metallurgy or sintering, with the strong limitations in terms of thickness and device integration. Iron co-deposition were investigated by means of the traditional electrochemical characterization, cyclic voltammetry (CV) and linear sweep voltammetry (LSV), and with more practical tools such as Hull cell. The films were deposited by means of potentiostatic and galvanostatic depositions, showing the dependence between experimental conditions and film composition (XRF). Results in in terms of morphology (SEM), composition/purity (EDX), microstructure (XRD) and magnetic properties (VSM) are shown.

[1] B. Y. Yoo, S. C. Hernandez, D. Y. Park, and N. V. Myung, “Electrodeposition of FeCoNi thin films for magnetic-MEMS devices,” Electrochim. Acta, vol. 51, no. 28, pp. 6346–6352, 2006.

[2] G. Panzeri, A. Accogli, E. Gibertini, C. Rinaldi, L. Nobili, and L. Magagnin, “Electrodeposition of high-purity nanostructured iron films from Fe(II) and Fe(III) non-aqueous solutions based on ethylene glycol,” Electrochim. Acta, no. Ii, 2018.

[3] A. P. Abbott and K. J. McKenzie, “Application of ionic liquids to the electrodeposition of metals,” Phys. Chem. Chem. Phys., vol. 8, no. 37, p. 4265, 2006.

[4] T. Welton, “Room-Temperature Ionic Liquids. Solvents for Synthesis and Catalysis,” Chem. Rev., vol. 99, no. 8, pp. 2071–2084, 1999.
The Effect of Catalyst on the Electroless Copper Plating of Textiles and Fabrics
Authors: Fox Daryl A , Taghavi Pourian Azar Golnaz , Begum Shakiela , Cobley Andy J
Published: February 2020

There are well established methods for the electroless plating of metals onto non-conducting surfaces such as polyimide and printed circuit boards (PCBs)1. After surface preparation of the substrate the electroless pre-treatment typically consists of a functionalisation stage followed by catalysation1. This latter stage deposits a catalytic metal (typically Pd) which initiates the electroless copper deposition reaction1. This approach, when applied to textiles, can produce a multi-functional material with high electrical and thermal conductivity but which is also flexible and wearable. However, the use of Pd as catalyst can significantly impact costs and so there has been work in recent years to investigate other more cost effective catalysts2. These have included Ag nanoparticles and, more recently, Cu nanoparticles2.

In this paper 3 approaches to electroless copper catalysation (based on Pd, Ag and Cu nanoparticles) are compared. Characterisation of the metallised textiles and fabrics was performed using approaches such as conductivity measurements, Scanning Electron Microscopy and Scanning White Light Interferometry to determine whether alternatives to Pd catalysts could be utilised. Functionalised nanoparticles dispersed and deposited in a variety of solvents are considered for catalytic activity using cyclic voltammetry, dynamic light scattering and UV-vis spectroscopy. In addition, ultrasonication, adhesion testing, catalyst loading as well as selected self-assembled monolayers are investigated to determine the optimum production parameters for a selection of fabrics.

This work is carried out as part of the MATUROLIFE project which is a European Union Horizon 2020 project that brings together two different disciplines, material science and design, to produce high added value assistive technology products. These items will be aesthetically pleasing as well as designed with functionality in mind.

“Additive Process for patterned metallised conductive tracks on cotton with applications in smart textiles", K.A.Wills, K. Krzyzak, J. Bush, R. Ashayer-Soltani, J.E. Graves, C. Hunt and A.J. Cobley, The Journal of The Textile Institute, DOI: 10.1080/00405000.2017.1340822 (2017).

“Ultrasound assisted dispersal, of a copper nanopowder for electroless deposition”, J.E. Graves, M.Sugden, R.E. Litchford, D.A. Hutt, T.J. Mason and A.J. Cobley, Ultrasonics Sonochemistry, 29, 428-438, (2016).
Bipolar Electrodeposition of Manganese Dioxide Nanoparticles on Gold Nanotubes
Authors: Experton Juliette , Wu Xiaojian , Wang Gelan , Martin Charles R
Published: February 2020

Manganese dioxide is an environmentally abundant and low-cost material that shows considerable interest for energy-related applications, such as supercapacitor and cathode material in batteries. However, its use is currently limited by its poor cyclability and its low ionic and electronic conductivities. To overcome these limitations, many strategies have been centered on the design of MnO2 nanoparticles to reduce the diffusion distance for the insertion cations.

Precisely controlling the location of MnO2 nanoparticle electrodeposition on the electrode can be challenging because of the need of continuous electrical contact. This is why we have developed a method to grow MnO2 nanoparticles on 3D nano-objects in the absence of a direct electrical contact. This method entails using gold nanotubes as bipolar electrode. A voltage of 2 V is applied across a gold nanotube membrane to generate redox reactions, one cathodic and one anodic, at either end of the tubes. The anodic reaction is chosen such that it forms MnO2 hemispherical nanoparticles at one opening of the nanotubes.

In this presentation, we will describe the mechanism of electrodeposition and growth rate of these MnO2 nanoparticles, as studied by electron microscopy, X-ray photoelectron spectroscopy and electrochemical techniques. We will also report chemical and electrochemical characterizations of these nanoparticles, such as conductivity and permselectivity measurements in lithium solution, in order to address the performance of MnO2 as a battery material. Finally, the effect of charging and discharging on the structure and electrochemical properties of MnO2 will be presented.
A Novel Photoelectrochemical Approach to Fight Biofilms and Reduce Undesired Microbiology
Authors: Fritz Mathias , Bund Andreas , Ullrich Hans-Juergen
Published: February 2020

The formation of biofilms, which may contain hygienically alarming microorganisms, is often observed in pipelines for drinking and cooling water systems. Recently, all German health offices were interviewed about their experiences in the surveillance of home water installations and stated that about 5% of cold water and 20% of warm water installations showed hygienic-microbiological peculiarities [1]. The technical repercussions of biofilm formation can lead to a decreased flow rate, filter blockage and a reduced heat transfer in cooling/heating circuits. Thus, there is high demand for efficient remedies to reduce microbial growth in such installations.

Research at various conducting surfaces showed a significant decrease of biofilm formation induced by oscillations of the electrochemical potential [2]. In our contribution, we will discuss recent results from our labs how the electrode of surface activated metal foils is influenced by illumination with visible light. The electrochemical setup comprises a solar simulator, which emits a defined wavelength as well as a commercial high power LED. Specifically, the influence of the wavelength, as well as the duration and intensity of the illumination were investigated. Furthermore, cyclic voltammetry and open circuit potential measurements were performed to identify the parameters with the strongest influence on the inhibition of biofilm growth. In the outlook, we will discuss results on the construction of a prototype for large-scale water treatment.

[1] Flemming, H.C.: Microbial Biofouling: Unsolved Problems, Insufficient Approaches, and Possible Solutions, Biofilm Highlights (2011), 81-109

[2] Schaule, G.: Effects of electric polarization of indium tin oxide (ITO) and polypyrrole on biofilm formation
, Water Science and Technology 58 (2008) 11, 2165-2172