bluuebunny/crossref_metadata_2025_split huggingface dataset:
Corrosion of an Aluminum Alloy (AA2024) Influenced By Microorganisms of a Bacterial Consortium
Authors: Paez Maritza Angelica 
Published: February 2020

In this work, corrosion of an aluminum alloy for aeronautical applications, AA-2024, influenced by a consortium of microorganisms was studied.
Microorganisms were isolated through environmental sampling, which was carried out in the auxiliary fuel in a Twin-Otter aircraft in Antarctic climate conditions. The identification of microorganisms was performed by sequencing of the 16S gene of ribosomal DNA (rDNA), which allowed distinguish a number of bacteria belonging to the genera Staphylococcus, Kocuria, Nosocomiicoccus and Tersicoccus. For all microroganismos, catalase test was positive.
Electrochemical measurements and morphological characterization of the surfaces was performed before, and after, different immersion times (1, 2, 3, 7 and 14 days) in minimum culture media, Twin (MMT), sterile and inoculated with the consortium and also, with each microorganism isolated.
Impedance diagrams for all immersion times showed a capacitive behavior characterized by a single time constant. Although short exposure times no corrosion process was evident, for longer times the resistance of aluminum oxide (Rox) decreased significantly, suggesting the occurrence of corrosion process, possibly mediated by microorganisms. Morphological changes of surfaces exposed to different media were examined by scanning electron microscopy (SEM) and atomic force microscopy (AFM).
The mechanism of corrosion, particularly that associated with Enzyme approach was studied performing potentiostatic measurements pyrocarbon electrodes modified with cobalt phthalocyanine. The latter compound catalyses the reduction of oxygen via two electrons, ie via hydrogen peroxide. Measurements were made in sterile and inoculated media and in the presence of oxygen. Electrochemical results show that the presence of microorganisms significantly alter the mechanism of oxygen reduction, particularly the reduction of oxygen to hydrogen peroxide. This would confirm the mechanism of the enzymatic approach in microbiologically influenced corrosion.
Self-Organizing Anodization in Pure Molten O-H3PO4
Authors: Altomare Marco , Nguyen Nhat Truong , Schmuki P. 
Published: February 2020

In 1995 Masuda et al. reported on a straightforward anodization approach that allowed for the growth of self-organized vertically-aligned alumina nanopores.1 Since then, electrochemical anodization has been widely investigated as a most suitable way to fabricate one dimensional (1D) functional oxide structures.2 Highly-ordered architectures of several metal oxides were successfully formed by anodizing in aqueous acidic solutions (e.g., Al2O3),1 fluoride containing aqueous or organic solvents (e.g., TiO2, Ta2O5, ZrO2, HfO2, etc.),3,4 and hot glycerol electrolytes (e.g., Al2O3, Ta2O5, TiO2).5-7

With this contribution we introduce a class of anodizing electrolytes, based on pure ortho-phosphoric acid (i.e., o-H3PO4), that provides high aspect-ratio highly-ordered oxide nanostructures on some of the most challenging elements such as W, as well as on more common elements such as Al, Ti, Nb.8

We describe how to tailor the structure of the formed anodic oxides by adjusting a set of key electrochemical parameters such as the electrolyte temperature, its water content, the applied voltage, and the anodization time. We show that under suitable conditions, an ideal equilibrium is established between field-assisted passivation of the metal and oxide dissolution, this leading to the growth of the anodic oxide layers in a highly ordered fashion.
Not only pure molten ortho-phosphoric acid but also other phosphorus-containing acids, namely, hot pure pyro- and poly-phosphoric acids, are able to establish the required self-organizing electrochemical conditions for the growth of ordered oxide structures. We propose that the role of the molten phosphate electrolyte is two-fold: i) it provides an environment with controlled and limited water content (that is the key oxidant), and ii) it provides phosphate ions that protect the anodic oxide from rapid dissolution, this allowing for a controlled growth of the metal oxide nanostructures.
(1) Masuda, H.; Fukuda, K. Science
1995, 268, 1466; (2) Roy, P.; Berger, S.; Schmuki, P. Angew. Chem. Int. Ed.
2011, 50, 2904; (3) Assefpour-Dezfuly, M. J. Mater. Sci.
1984, 19, 3626; (4) Kowalski, D.; Kim, D.; Schmuki, P. Nano Today
2013, 8, 235; (5) Melody, B.; Kinard, T.; Lessner, P. Electrochem. Solid-State Lett.
1999, 1, 126; (6) Lu, Q.; Alcalá, G.; Skeldon, P.; Thompson, G.; Graham, M. .; Masheder, D.; Shimizu, K.; Habazaki, H. Electrochim. Acta
2002, 48, 37; (7) Kim, D.; Lee, K.; Roy, P.; Birajdar, B.; Spiecker, E.; Schmuki, P. Angew. Chemie Int. Ed.
2009, 48, 9326; (8) Altomare, M.; Pfoch, O.; Tighineanu, A.; Kirchgeorg, R.; Lee, K.; Selli, E.; Schmuki, P. J. Am. Chem. Soc.
2015, 137, 5646.

Figure 1
Corrosion Behavior of Structural Materials for Use in Solar Thermal Molten Salt Power Plants
Authors: Summers Kodi , Chidambaram Dev 
Published: February 2020

Introduction

Increasing greenhouse gas emissions and electricity demands coupled with decreasing fossil fuel reserves has dramatically increased the need for alternative energy sources. Solar energy continues to be the most promising carbon-neutral source with more energy incident on the Earth in 1 hour than is consumed in an entire year (1). Concentrated solar plants (CSPs) have been gaining interest due to their relatively high efficiencies of 37-42% (2). Molten salt CSPs have been of particular interest because these designs can achieve the highest temperatures and efficiencies (1). Solar technologies also need to account for periods without sun that can only be solved by developing a method of storing excess energy produced during peak producing time. Concentrated solar plants that use a molten salt heat transfer fluid (HTF) have the ability to store sensible heat for up to 15 hours (3).

Experimental

Experiments were conducted at operating temperatures of a typical CSP using a molten nitrate salt HTF of 300 - 500°C in a static, atmospheric environment. The molten salt working fluid studied was an off-eutectic 40/60 wt.% KNO3/NaNO3 mixture. The alloys studied were stainless steel 316, super-austenitic Incoloy 800H, and carbon steel. Each of these alloys was exposed to the salt for 100 hour exposures and galvanic couples at 300, 400 and 500°C. The alloys were studied electrochemically to simulate long-term exposures analogous of plant operation. The oxide film that is formed on each sample was then characterized to correlate the surface chemistry to the corrosive behavior of the salt on each alloy. The surface characterizations are performed using X-ray diffraction, X-ray photoelectron spectroscopy and Raman spectroscopy. The salt was also studied by dissolving in deionized water and analyzing the solution by inductively coupled plasma optical emission.

Results

Figure 1 shows Raman spectra for SS 316 exposed at 300°C molten KNO3/NaNO3salt mixture for 100 hours. Based on the Raman shift, hematite and magnetite features can be observed on the surface (4). Similarly, the surface chemistry of all alloys are correlated to their corrosion behavior.

Figure
1
: Raman spectrum obtain from SS316 exposed to molten nitrate salt at 300C for 100 hours.

Acknowledgements

This material is based upon work supported by the National Science Foundation under Grant No. IIA-1301726.

References

1. D. Barlev, R. Vidu and P. Stroeve, Solar Energy Materials and Solar Cells, 95, 2703 (2011).
2. M. T. Dunham and B. D. Iverson, Renewable and Sustainable Energy Reviews, 30, 758 (2014).
3. H. L. Zhang, J. Baeyens, J. Degrève and G. Cacères, Renewable and Sustainable Energy Reviews, 22, 466 (2013).
4. RDSS - A Raman spectra library software using peaks postion for fast and accurate identification of unknown inorganic compounds, in.

Figure 1
(Invited) Process and Integration of Dielectrics Required for 10nm and Beyond Scaling
Authors: Clark Robert D. , Tapily Kandabara , Consiglio Steven , Hakamata Takahiro , O'Meara David , Newman Daniel , Collings Michael , Szymanski Dennis , Wajda Cory S. , Leusink Gert J. 
Published: February 2020

Over the past decade traditional scaling by simple linear shrinking has effectively ceased as IC makers have adopted new 3-dimensional device structures, complex integration schemes and new processes and materials for an expanding number of applications in order to overcome fundamental physical limits. This trend will accelerate as devices are scaled to a level approaching atomic dimensions. Dielectric materials with tailored properties are required to meet future device needs. And deposition processes that are self-limited (e.g. Atomic Layer Deposition (ALD)), or self-directed (e.g. selective deposition) will enable those materials to be used in scaled 3D devices. Highly tailored ALD processes are being investigated to fabricate functional material layers. Interspersed treatments and doping to make ternary materials may be used to modify the physical and electrical properties of ALD films further in order to optimize the resulting physical or electrical properties. To improve device contacts, ultra-thin dielectrics and metal layers may be deposited inside of high aspect ratio contact structures in order to provide lower contact resistivity- or may be used to provide solutions for integration of new contact structures. Selective deposition processes can be used to deposit functional materials only where they are needed, thus reducing the patterning burden during IC manufacturing. Future use of new transistor channel materials, such as III-V and Ge, will require the use of ALD gate dielectrics with compatible treatment schemes in order to passivate defects and provide EOT scaling inside of ultra-high ratio replacement gate structures. Examples of these and similar processes will be described and discussed with the goal of discerning a path beyond 10nm devices.
The Study on Keeping the Pad Surface Condition in W CMP Process
Authors: Oh Dong Won 
Published: February 2020

Chemical Mechanical Polishing (CMP) is the most effective planarization process in the integrated circuit fabrication. CMP Process has been applied in various purposes. Different types of surfaces are polished for each object, including oxides, Cu, W and others.
The performance of each CMP Process depends on ability of tools and limitation of its consumables. Materials of CMP Process are roughly separated slurry, pad, conditioning disk, above all, it is a difficult problem to extend its life time of pad and conditioning disk for mass fabrication.
We were motivated to improve its change period. In this work, we focused on improvement of life time of pad and disk of W CMP Process in NAND FLASH Devices. Because that is less than half the change period to another CMP Processes, the improvement of efficiency of mass fabrication is greatly required. The W CMP Process consists of two step processes, the first step is polishing bulk W film and the second step is polishing oxide mold which was patterned by W film. In the first step for removing bulk W film, it is limited by increasing the polishing time according as accumulation processing wafer counts. On the other hand, in the last step for removing oxide mold which was patterned by w film, it is limited by decreasing the pad groove depth because the pad wear rate is extremely high than other CMP Process.
In this work, we studied characteristics of each step in W CMP Process to extend the life time. We focused on the ability improvement of diamond disk to keep the steady removal rate and to reduce the lower pad wear rate. We developed the novel diamond disk as controlling the shape and height of protrusion of diamonds.
Mixed Strategy Combination of Pressure and Velocity Control for Chemical Mechanical Planarization of Patterned Wafers
Authors: Chandra Abhijit , Bastawros Ashraf , Wu Kuan-Chuen , Karra Pavan 
Published: February 2020

The Preston equation suggests interoperability of material removal rate (MRR) by either pressure or velocity. Traditionally, planarization is pursued by pressure control. A novel velocity control strategy for a single step on a blanket wafer is recently proposed. The effectiveness of both strategies on patterned wafers is numerically investigated here, using the MIT Mask layout. Superiority is observed to be pattern dependent, scaling with MRR and material choice. However, improved quality at feature scale induces deterioration at the die scale. Scratch generation propensity, which is a micro- or even nano-scale phenomenon, is typically invariant to macro-level control strategies. A mixed control strategy produces better results in terms of finish quality and productivity, by attaining the targeted local and global planarization in less polishing time, compared to individual strategies.
Surface Characterization Driven CMP Optimization for GaN
Authors: Karagoz Ayse , Siebert Max , Leunissen Peter , Basim G. Bahar 
Published: February 2020

III-V nitride semiconductors are widely used for optoelectronic devices such as blue lasers diodes (LDs), light-emitting diodes (LEDs), and high power, high frequency field effect transistor (FET) devices [1]. Among these, GaN has exceptional characteristics such as providing direct and wide band-gap energy and high electron mobility and hence is typically used for the high power applications and LEDs [2]. The performance and quality of the optical devices directly correlate to the level of surface defectivity and planarization. Consequently, application of Chemical Mechanical Planarization (CMP) with minimal defectivity is required. However, introducing CMP on a film that is poorly grown due to epitaxial challenges such as GaN [3], in addition to GaN being a very robust film to effectively remove material limits the CMP performance.
In this study, a systematic experimental approach is followed to determine the conditions to enhance material removal rate while controlling surface defectivity for GaN CMP. Two different crystallographic orientations of the GaN are characterized and compared to a commercial 2” GaN wafer to optimize the CMP material removal rate performances on the basis of the surface electrical, topographic and crystallographic properties. Silica based slurries were used as a function of pH, type of polishing pad and conditioning. CMP responses of Ga reach orientation (Face A) and N reach orientation (Face B) were different while the commercial 2” GaN wafer with unknown surface crystallographic structure was observed to have similar behavior with the Face A bulk wafer. The optimized CMP conditions as a function of surface characteristics helped in increasing the very limited material removal rates of GaN while minimizing defect formation and enhancing the selectivity against silica.
References:

Hua Gonga, Guoshun Pana, Yan Zhoua, Xiaolei Shi, Chunli Zoua, Suman Zhanga,“Investigation on the surface characterization of Ga-faced GaN after chemical-mechanical polishing”Applied Surface Science, Volume 338, Pages 85–91, (2015).

Hideo A., Hidetoshi T., Koji K., Haruji K., Kazuhiko S.,and Toshiro D., Chemical Mechanical Polishing of Gallium Nitride with Colloidal Silica, Journal of The Electrochemical Society, 158 (12) H1206-H1212, (2011).

Tavernier P. R., Margalith T., Coldren L.A.,DenBaars S.P., and Clarke D.R., Chemical Mechanical Polishing of Gallium Nitride, Electrochemical and Solid-State Letters, 5,(8),G61-G64 (2002).
Plasma Spray Pyrolysis: A Rapid, Scalable Method for Making Mixed Metal Oxide Alloys for Enabling Accelerated Materials Discovery
Authors: Sunkara Mahendra Kumar , Ajayi Babajide , Kumari Sudhesh , Spurgeon Joshua M , Jasinski Jacek B , Jaramillo-Cabanzo Daniel Felipe 
Published: February 2020

Many grand challenges in energy conversion and storage need discovery of new materials. However, there are not too many reported synthesis approaches that could easily be implemented for screening and rational understanding of structure-behavior relationships. Specifically, the challenges include semiconductors for photoelectrochemical water splitting, stable electrocatalysts for oxygen evolution and reduction, and nitrogen reduction and for many heterogeneous gas-solid reactions including carbon dioxide reduction. Many of the above challenges require synthesis of multi-element alloys with composition over entire range regardless of phases present.
Here, we report a new synthesis technique that can be used to accelerate the discovery of materials for various energy conversion and storage applications. Specifically, this technique allows a rapid and controlled synthesis of mixed metal oxide particles using plasma oxidation of liquid droplets containing mixed metal precursors. The conventional wet chemical methods for synthesis of multi-metal oxide alloys often require time-consuming high pressure and temperature processes, and so the challenge is to develop rapid and scalable techniques with precise compositional control. The concept is demonstrated by synthesizing binary and ternary transition metal oxide alloys with control over entire composition range using metal precursor solution droplets oxidized using atmospheric oxygen plasma. The results show the selective formation of metastable spinel and the rocksalt solid solution phases with compositions over the entire range by tuning the metal precursor composition. The synthesized manganese doped nickel ferrite nanoparticles, NiMnzFe2-
zO4 (01), exhibits considerable electrocatalytic activity towards oxygen evolution reaction (OER), achieving an overpotential of 0.39V at a benchmarking current density of 10 mAcm-2 for a low manganese content of z = 0.20.
SEM Analysis of Electrophoretically-Deposited Cobalt Ferrite Films
Authors: Verma Neil , Talbot J. B. 
Published: February 2020

Cobalt ferrite nanoparticles (20 nm) were synthesized and electrophoretically deposited onto aluminum foil, graphite paper, and carbon felt (3 mm thickness) from a 100% ethanol bath. Linear sweep voltammetry was used to test the electrocatalytic activity of the deposits relative to blank substrates for the oxidation of ammonium sulfite to ammonium sulfate in a proposed sulfur ammonia (SA) water-splitting solar thermochemical cycle. Subsequently, scanning electron microscopy (SEM) was used to study the morphology of the cobalt ferrite films.
The effects of electrophoretic deposition conditions on deposit morphology and the effects of deposit morphology on electrochemical activity in 2 M ammonium sulfite were investigated. EPD on aluminum and graphite paper was performed such that particles were deposited on only one side of the substrate. For the 3 mm thick carbon felt, particles were deposited on both sides of the substrate to improve deposit uniformity throughout the sample. Both deposition time (0-10 minutes) and deposition current (0-16 mA) were varied to analyze their effects on the resulting deposit films for all substrates.
For the EPD conditions studied, a critical deposit thickness was found for graphite paper and carbon felt for maximum electrochemical current density, where additional deposited particles reduced the electrocatalytic activity of the deposits. This thickness was estimated to be 3 particle layers for the graphite paper substrate. At this thickness, the deposit had a 5.5 fold increase in activity relative to a blank graphite paper substrate. SEM micrographs showed that the deposit uniformly covered the substrate and had noticeable cracking. For the carbon felt, the critical deposit thickness was observed to be approximately 1-2 particle layers via SEM analysis. Moreover, SEM images showed that the deposit was a uniform film with no cracking. At this thickness, the deposit had a 4.3 fold increase in activity compared to a blank carbon felt substrate.
Mesoscale Particle-Based Model of Colloidal Suspensions in Electric Fields
Authors: Giera Brian , Zepeda-Ruiz Luis , Pascall Andrew J. , Weisgraber Todd 
Published: February 2020

We evaluate a particle-based model of colloidal suspensions that undergo electrophoretic motion[1] and deposition using an extensive set of mesoscale simulations that characterize experimentally relevant colloidal suspensions. We parameterize the model using only measurable quantities from suspensions that have properties of non-polar and aqueous solvents or ionic liquids with monodisperse polystyrene colloids between 1 nm - 1 μm in radius. The model accurately describes diffusive and electrophoretic motion of experimentally relevant colloidal suspensions. Furthermore, we extend the model to investigate electrophoretic deposition. The model is uniquely poised to elucidate how the deposit morphology depends on electric field strength, suspension properties, and colloid packing fraction because the model explicitly computes inter-particle interactions of colloidal suspensions.
[1] Giera, B.; Zepeda-Ruiz, L. A.; Pascall, A. J.; Kuntz, J. D.; Spadaccini, C. M.; Weisgraber, T. H. Mesoscale Particle-Based Model of Electrophoresis. Journal of the Electrochemical Society. The Electrochemical Society 2015, pp D3030–D3035.
Epd: From Order to Chaos By the LbL Modification of the Particle Surfaces
Authors: Gonzalez Zoilo , Filiatre Claudine , Castro Yolanda , Mendoza Carlos , Sanchez-Herencia Antonio Javier , Ferrari Begoña 
Published: February 2020

Electrophoretic deposition (EPD) is a colloidal processing method which consists in the electrically driven movement and deposition of charged particles onto a conductive substrate. Understanding the colloidal behavior of nanoparticles is therefore mandatory to prepare stable and disperse suspensions suitable for EPD. Moreover, up today most of the proposed models for the EPD kinetics have been formulated considering the electrophoresis process. However, the effect of other parameters than electrophoresis over the kinetics, the deposition feature or the coating morphology, has been mainly empirically considered. In fact, in the well-known kinetics models based on the electrophoretic mobility of particles, these effects have been only quantified throughout the sticking factor, a probabilistic and empiric parameter.
A new perspective of the particles clustering can be extracted combining the modelling of interaction forces among particles, with the substrate coverage determined under laminar flow. In stable suspensions under similar electric conditions, changes in nature, length and ionization strength of surface modifiers determine the interaction forces among particles, resulting in an effective tool to manage particles flocculation and hence kinetics and ordering during the film growth. But also agglomerates fashioned by a Layer-by-Layer structure, built from the alternation of cationic and anionic polymers as modifiers of the particle surface, can contribute to tailor and intensify the deposition. The modification of the EPD kinetics induced by changes in the colloidal chemistry of the suspension of TiN nanoparticles and Ni(OH)2 nanoplatelets will illustrate mentioned phenomena.