bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Guest Binding on a Redox Active Three Hydrogen Bond Array
Authors: He Ran , Smith Diane K. 
Published: February 2020

Proton-coupled electron transfer (PCET) reactions are essential to many of the fundamental chemical processes of life. In the Smith group we are investigating the role of H-bonding intermediates in PCET by studying the voltammetry of compounds capable of multiple, strong H-bond interactions. In particular we have studied a p-phenylenediamine-based urea, U(H)H, which contains two H donor sites making a DD array. In this study, the phenyl group in U(H)H is replaced by an imidazole group to form a three hydrogen bond array, UImH. In this array, the two major conformers both present a DDA H-bond motif (1 and 2 in Fig 1). Therefore, AAD arrays, such as APy, are needed as guest compounds to form three intermolecular non-covalent contacts.
The cyclic voltammetry of UImH has been examined in methylene chloride and acetonitrile with platinum (Pt) and glassy carbon (GC) electrodes. On both electrodes, CV’s show two, closely-spaced, reversible waves of similar height. We initially hypothesized that the first electron oxidation happens on the phenylenediamine unit, followed by rapid intramolecular proton transfer in conformer 2, Fig. 1. The second electron is removed at a slightly more positive potential due to the positive charge remaining on the array after the first oxidation. However, the voltammetry is observed to have a strong concentration dependence and this cannot be explained by this mechanism. Based on the CVs we now propose the first wave is due to loss of 2e- from UImH with an intramolecular PT to form UImH2+. Then UImH2+ undergoes an intermolecular PT with unreacted UImH to produce UIm+ and HUImH+. The second wave is due to 2e- oxidation HUImH+ to form HUImH3+ at a more positive potential. Lastly, an intermolecular PT between HUImH3+and UIm+ gives the final product UImH2+.
Addition of the guest, APy, results in is a slight increase in the current of the CV waves of UImH. This could be due to preferential binding and stabilization of UImH which prevents decomposition and adsorption. Surprisingly, very little change in the potential of the CV wave is observed upon addition of the guest, indicating that oxidation does not change binding strength. Even though the H-donors in UImH2+ should be stronger than in UImH, the H-acceptor in UImH2+ is weaker than in UImH. So the two effects cancel each other.

Figure 1
Nano Sized Defect Free Al2O
3
Thin Film for High Performance Gas Barrier
Authors: Jang YunSung , Hong MunPyo 
Published: February 2020

Recently, our interests in flexible display for next generation have been increased. Plastic substrate is used for flexible display. However it has less chemical resistance, heat resistance, gas transmittance resistance characteristics than glass substrate. By these reasons, plastic substrate requires functional coatings. Because the OLED is degraded by moisture and oxygen, it requires intensely ultralow Water Vapor Transition Rate (WVTR) as 1ⅹ10-6gm-2day-1. To achieve the ultralow WVTR, defects must be prevented.
Defects generated by particles can be prevented carefully controlling the process, but defects generated in grain boundary have to be annealed to get rid of them. Organic materials have weakness for heat so annealing process has to be avoid. In this study, we developed Al2O3 nano-structure single gas barrier layer using Neutral Beam Assisted Sputtering (NBAS) process. The NBAS process can be continuously changing crystalline structure from amorphous phase to nano-crystal phase of various grain sizes within single inorganic thin film. These NBAS process effect can lead to formation of nano-structure barrier layer which effectively passivate and healing gas diffusion pathways between grain boundaries. As a result, we confirmed nano-structure of NBAS processed Al2O3 single gas barrier layer through the dielectric constant measurement, Ellipsometry, AFM, and TEM analysis. Finally, WVTR property of Al2O3 nano-structure single gas barrier layer is measured under 1ⅹ10-6gm-2day-1. The Al2O3 nano- structure single gas barrier layer is very suitable in the OLED application.
Probing the Role of Organic Additives on the Film Formation Mechanism Relevant to Metal CMP
Authors: Mlynarski Amy , Janes Lisa M. , Keleher Jason J 
Published: February 2020

With the increasing demand of high performance technology, the necessity to improve the mechanics of electronic devices is becoming of great importance. This requires atomic level planarization to avoid defects on the surface of integrated circuits (IC) and hard disk drive (HDD) media through CMP by removing the metal complex film formed. Traditional CMP systems incorporate a synergistic interaction between slurry chemistry and various mechanical parameters to achieve high surface quality while ensuring surface planarity. In order to understand this relationship, it is necessary to probe the film forming capabilities of oxidizers, complexing agents, and corrosion inhibitors on the substrate surface. The changes and dissolution of the film formed on the surface will be analyzed through the comparison of activation energy and Open Circuit Potential (OCP). More specifically, the separate molecular interaction of Benzotriazole (BTA) and Salicylhydroxamic Acid (SHA), and the substrate will be studied through the quantization of activation energy. The difference in the surface quality of the substrate, dependent on the film formation mechanism, will be understood through Atomic Force Microscopy (AFM). This work aims to show how the use of electrochemical techniques and surface spectroscopy can be useful in understanding the underlying mechanism of film formation on Cu and NiP substrates. Previous studies have shown promise that the use of various additives plays an intricate role on the films formed, relying heavily on the metal substrate used.
Deposition and Electrical Characterization of CaCu3Ti4O12 Thin Films
Authors: Skaria Giji , Sundaram Kalpathy B 
Published: February 2020

There is an increased interest in very high dielectric constant (high-k) material studies due to their potential applications in energy storage elements. In this aspect, the perovskite materials seem to achieve very high-k values [1]. In this study, the focus has been to deposit thin films of CaCu3Ti4O12. These films are deposited by RF magnetron sputtering process using CaCu3Ti4O12target. The films are deposited under varies deposition conditions that include argon gas flow ratios, process pressures and RF power. Metal–insulator–metal (MIM) structures have been fabricated using aluminum film as the electrodes. The electrical properties of the films have been characterized and reported as a function of deposition parameters for the above MIM structures.
REFERENCE:
[1] M.A. Subramanian, Dong Li, N. Duan, B.A. Reisner, A.W. Sleight, High Dielectric Constant in ACu3 Ti4 O12 and ACu3 Ti3 FeO12 Phases
(Invited) Silicon Nanocrystals: Size Control, Basic Understanding and High Quantum Yields
Authors: Gutsch Sebastian , Laube Jan , Zelenina Anastasia , Hiller Daniel , Zacharias Margit 
Published: February 2020

Controlled fabrication of Si nanocrystals via the SiOx/SiO2 superlattice approach enables size control as well as density control [1]. The resulting layer arranged Si nanocrystals represent a model system to systematically study photonic and electronic properties of indirect gap quantum dots. Hence a deeper understanding can be developed for absorption, recombination, carrier kinetics and transport. As example, the temperature dependence of confined excitons in Si quantum dots and their respective temperature depending band gap will be analyzed for different sizes and will be compared with theory prediction. [2] The interplay of radiative and non-radiative recombination will be studied using recombination kinetics based on detailed time resolved measurements. [3] In addition, the origin of the luminescence in Si2N3embedded Si NCs are discussed. [4] Transport properties will be evaluated as a function of NCs size and distance. [5] Finally, systematic doping experiments with P will be analyzed for doping efficiency, in-cooperation into the Si NCs and self-purification, and electronic transport. [6, 7]
[1] M. Zacharias et al. Appl. Phys. Lett. 80 (2002) 661.
[2] A. M. Hartel et al. Phys. Rev. B 85, 165306 (2012).
[3] A.M. Hartel et al. Rev. B 87 (2013) 035428.
[4] A. Zelinina et al. J. Appl. Phys. 114 (2013) 184311.
[5] S. Gutsch et al. J. Appl. Phys. 113 (2013) 133703.
[6] H. Gnaser et al. J. Appl. Phys.113 (2013) 034304
[7] S. Gutsch et al. Appl. Phys. Lett. 106 (2015) 113103.
Synthesis of Nano-Phosphor By Water Assisted Room Temperature Solid State Reaction (WASSR) Method
Authors: Toda Kenji , Hasegawa Takuya , Kaneko Tatsuro , Toda Ayano , Kim Sun Woog , Uematsu Kazuyoshi , Ishigaki Tadashi , Koide Junko , Toda Masako , Kudo Yoshiaki 
Published: February 2020

A solid-state reaction method has been usually used as a basis synthesis processing technique to obtain the ceramic materials, including phosphor materials, because of its very simple and easy. However, ceramic materials are generally synthesized at high temperature when the solid state reaction method used as synthesis method. Because ionic-diffusion in ionic crystal is very slow at room temperature, high temperature is essential for solid state reaction. The high temperature synthesis leads to increase in the processing cost and irregular particle morphology of the obtained powder. In contrast, we have proposed the two novel solid phase synthesis technique to synthesize the ceramic materials at low temperature below 100 °C without after any chemical or physical treatment. We refer to these synthesis techniques as water assisted room temperature solid state reaction (WASSR) method and solid hydratethermal reaction (SHR) method.1-3 We successfully synthesized the functional ceramic materials including phosphors. Furthermore, we demonstrated that the reaction mechanism of novel low temperature synthesis methods is different from the conventional solid state reaction and solution reaction. In this study, we present the practicability of our original novel solid state reaction methods on an industrial application in the ceramic oxide materials synthesis processing.
References

K. Toda, M. Sato, K. Uematsu, and T. Ishigaki, Japanese Unexamined Patent Application Publication No. 2011-16670 (2009).

S.W. Kim, T. Kaneko, K. Toda, K. Uematsu, M. Sato, J. Koide, M. Toda, and Y. Kudo, IDW'2014, PH1-3 (2014).

T. Kaneko, S.W. Kim, A. Toda, K. Uematsu, T. Ishigaki, K. Toda, M. Sato, J. Koide, M. Toda, Y. Kudo, T. Masaki, and D.H. Yoon, Sci. Adv. Mater., (2015) in press. doi:10.1166/sam.2015.2364.
(Energy Technology Division Research Award) Electrolytes in Advanced Electrochemical Systems for Energy Storage and Conversion
Authors: Zawodzinski Thomas A. 
Published: February 2020

The electrolyte in electrochemical systems plays a central role both literally and figuratively. For low temperature systems, whether liquid or polymer electrolyte, the chemical and physical properties of this component has functions that go far beyond a linear ohmic response. Non-linear aspects arise related to the role of water in devices such as fuel cells. The separator aspect of the membrane dictates that it play roles in mediating cross-over in multi-component systems. In practical systems, the concentrated solutions to which a membrane might be exposed render a detailed understanding of its behavior critical. And, of course, electrolytes must permeate through porous electrodes to complete the circuit and allow the primary transduction events to occur at an active electrode surface site.
These aspects play major roles in fuel cells, batteries and other electrochemical devices that are at the forefront of electrochemists’ contribution to the energy and environment fields in this symposium. The scientist and engineer working on these devices often have two choices: find a fundamental solution to the issue through developing advanced electrolytes or work around the problem with the materials at hand. (I leave it to the reader to decide which choice would be favored by the scientist and engineer respectively!) Nonetheless, each approach informs the other: it is important to have some sense of the underpinnings of the problem from each perspective. As each new and potentially more complicated system is studied, it is necessary to review the available understanding of physical chemistry and transport of the electrolyte and, as needed, augment it.
In this presentation, after a brief overview of some early efforts and resolutions, examples of the state of the art of our understanding of electrolyte functions in redox flow batteries and in fuel cell electrodes will be presented. Descriptions of processes occurring at scales from molecular to macro-scale will be presented. Of particular interest in the flow battery context, and of general interest for electrosynthesis, is a description of the complex interplay between component interactions with each other and with membranes. For the fuel cell electrodes, unraveling of processes that connect structure and function at multiple levels is a primary unknown. In particular, the behavior of ionomer within the layer and the relationship of that behavior to ionomer interactions with the other components will be discussed.
Finally, in each case, these aspects will be placed in context of device-level issues that are caused and prospects for possible or actual solutions to these issues will be discussed. To conclude reflections will be presented on issues that were ‘left behind’ incompletely resolved during development of some devices.
Preparation of Solar-Grade Silicon By Chemical and Electrochemical Processes
Authors: Homma Takayuki , Kunimoto Masahiro , Yang Xiao , Yasuda Kouji , Fukunaka Yasuhiro , Nohira Toshiyuki 
Published: February 2020

As the demands for renewable energy have keep increasing, further massive production of solar-grade silicon (SOG-Si), which is key material for large scale solar cells, has been highly required. Conventional process for its production is based upon carbo-thermic reduction of white silica ore followed by purification process by distilling chlorosilane species, which needs substantial energy consumption and having problems for lack of the resources. For an alternative approach for this, we have developed a series of process to form the SOG-Si material based on the chemical purification of silica using aqueous solution [1] and electrochemical reduction using molten salt [2]. Here we will introduce our approaches for developing these processes. For the source of SOG-Si, we focused on diatomaceous earth, which is earth-abundant material consisting of porous silica. After wet chemical treatment with acid and alkaline solutions, most of the impurities except light elements such as B could be removed. Then solvent extraction using channel-flow type reactor is applied for eliminating the light element with quite high efficiency, and the 7N level purity has been achieved [3, 4]. Then the silica was reduced by direct electrochemical reduction process using CaCl2 molten salt as an electrolyte, and crystalline Si was successfully obtained. To develop a continuous production process, we designed the feeding system for silica powder and confirmed steady reaction for reducing silica to Si, and systematically investigated the reaction process for its optimization [5,6].
This work was supported by CREST, JST.
[1] M. Bessho, Y. Fukunaka, H. Kusuda, T. Nishiyama, Energ. Fuel., 23, 4160 (2009).
[2] T. Nohira, K. Yasuda, Y. Ito, Nature Material, 2, 397 (2003).
[3] N. Matsuo, Y. Matsui, Y. Fukunaka, T. Homma, J. Electrochem. Soc.,
161, E93 (2014).
[4] T. Homma, N. Matsuo, X. Yang, K. Yasuda, Y. Fukunaka, T. Nohira, Electrochim. Acta, 179, 512 (2015).
[5] X. Yang, K. Yasuda, T. Nohira, R. Hagiwara, T Homma, J. Eelectrochem. Soc., 161, D1 (2014).
[6] X. Yang, K. Yasuda, T. Nohira, R. Hagiwara, T. Homma, Metall. Mater. Trans. B, in press.
Preparation of Cu2SnS3 Layers By Sulfurization of Electrodeposited Cu-Sn Multilayer Precursors
Authors: Sylla Diouldé , Creus Juan , Espindola-Rodriguez Moises , Placidi Marcel , Oliva Florian , Saucedo Edgardo , Perez-Rodriguez Alejandro 
Published: February 2020

Semi-conductors of the Cu–Sn–S system are attracting great interest because of their promising photocatalytic activity, non linear optical properties and potential as photovoltaic p-type absorber.
Among the different ternary sulfides, Cu2SnS3 (CTS) is one of the most relevant compound for solar cell applications due to its high light absorption coefficient
(> 104 cm–1) and appropriate band–gap energy values between 0.93 and 1.35 eV dependent on the different crystal structure of the polymorphic compound. Different methods have been reported for the synthesis of CTS, such as conventional solid-state reaction [1] and solvothermal process [2], mainly for powder preparation, whereas thin films have been deposited by spray pyrolysis technique [3], and also from direct sulfurization of sputter deposited [4] or electrodeposited [5] metal precursors.
Electrodepostion (ED) has a strong interest because of its relatively easy scalability to industrial processes and its potential for reduction of costs in relation to vacuum based technologies.
In this communication, we report the preparation and characterization of ternary CTS thin films using a sequential ED of Cu and Sn metallic layers onto Glass/Mo substrates in different deposition sequences and number of sublayers ((Cu/Sn)k and (Sn/Cu)k, k = 1; 2) followed by a thermal annealing treatment under S containing atmosphere.
The properties of the CTS absorber are strongly influenced by the morphological and structural characteristics of the metallic stacks precursors that depend on the ED operating conditions. In this case, the influence of electrolyte formulation and applied potential on the microstructure and morphology of the Cu–Sn precursors will be deeply studied. Then, we will investigate in detail how the stacking order of the precursor films affect the microstructure and optical properties of the resultant CTS absorbers. Moreover, our preliminary results of the growth of CTS thin films obtained by an alternative ED approach that we still develop in our laboratory, will be report and compare with the results obtained from a more conventional ED synthesis discussed above.
[1]. M. Onoda, X. Chen, A. Sato, H. Wada, Mater. Res. Bull. 35, 1563 (2000)
[2]. B. Li, Y. Xie, J. Huang, Y. Qian, J. Solid State Chem. 153, 170 (2000)
[3] M. Adelifard, M. Mehdi, B. Mohagheghi, H. Eshghi, Phys. Scr. 85, 035603 (2012)
[4] P.A. Fernandes, P.M.P. Salom, A.F. da Cunha, J. Phys.
D Appl. Phys. 43, 215403 (2010)
[5] D.M. Berg, R. Djemour, L. Gutay, S. Siebentritt, P.J. Dale, X. Fontane, V. Izquierdo-Roca, A. Pérez-Rodriguez, Appl. Phys.
Lett
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(Keynote) Formulation for the Treatment of Multiple Electrochemical Reactions and Associated Speciation for the Lithium-Silicon Electrode
Authors: Verbrugge Mark W , Baker Daniel R , Xiao Xingcheng 
Published: February 2020

We develop a theory and commensurate equations to model the thermodynamics, electrochemistry, and species transport of substitutional alloys subject to multiple electrochemical reactions, and we apply the treatment to the lithium-silicon (Li-Si) system [1]. The approach is general in that we expect it is applicable to simulate the electrochemical-reaction behavior of known substitutional-alloy and insertion-electrode materials of interest relative to today’s and near-future electrode materials. Central to the approach is the treatment of slow-scan voltammetry to gather information usually obtained by data differentiation associated with differential voltage spectroscopy; we show that the approach taken here allows for an accurate description of very low-rate behavior (0.01 mV/s), which we refer to as dynamic equilibrium (see Fig. 1).
We employ directly the experimental results from [1], corresponding to a silicon thin-film (67 nm) electrode deposited on a copper current collector. CR2032 coin cells were assembled with the Si thin film as the working electrode and a lithium foil as the counter-reference electrode.
To construct the model in [1], a look-up table was employed to evaluate the variation in the open-circuit potential with lithium content. In the current work, we develop consistent thermodynamic and electrochemical-reaction treatments that capture the salient features of the Li-Si experimental data and should prove to be of general utility for the treatment of substitutional alloys and insertion electrodes [2]. We employ the low-scan-rate voltammetry data reported in [1], which simplifies material balances, as diffusion resistance is negligible, and species concentrations are uniform throughout the film, although they vary with time. Last, we provide a discussion of results, including a perspective on the potential implications of the proposed treatment (with an emphasis on how the thermodynamic treatment influences transport relations based on the Stefan-Maxwell framework) and important open questions. The model is shown to compare favorably with experimental results obtained from thin-film Li-Si electrodes conducted at moderate potential-scan rates, with irreversible behavior governed by charge-transfer (interfacial) resistance; cyclic voltammetry results are shown in Fig. 2.

M. Verbrugge, D. Baker, X. Xiao, Q. Zhang, and Y-T. Cheng, “Experimental and theoretical characterization of electrode materials that undergo large volume changes and application to the lithium-silicon system,” J. Phys. Chem. C., 119(2015)5341.

M. Verbrugge, D. Baker, and X. Xiao, “Formulation for the treatment of multiple electrochemical reactions and associated speciation for the lithium-silicon electrode,” J. Electrochem. Soc., 163(2016)A262-A271.

Figure 1
Mathematical Models for the Impedance Response of Subcutaneous Glucose Sensors
Authors: Harding Morgan , Orazem Mark E. , Tribollet Bernard 
Published: February 2020

Since 1974, the artificial pancreas has been acknowledged by the greater scientific community to be a possible way to manage type 1 diabetes [1]. In 2008, a case study showed that a subcutaneous continuous glucose monitor sensor could be implanted for 28 days in a patient with type 1 diabetes [2]. However, commercially available subcutaneous continuous glucose monitors are generally changed every seven days to avoid unreliable results. The object of this work is to explore the potential of impedance spectroscopy to monitor the state of health of subcutaneous continuous glucose monitor sensors.
A mathematical model has been developed for the impedance response of a glucose oxidase enzyme-based electrochemical biosensor. The model accounts for a glucose limiting membrane GLM, which controls the amount of glucose participating in the enzymatic reaction. The glucose oxidase was assumed to be immobilized within a thin film adjacent to the electrode. In the glucose oxidase layer, a process of enzymatic catalysis transforms the glucose into peroxide, which can be detected electrochemically. This system may be considered to be a special case of the coupled homogeneous and heterogeneous reactions addressed by Levich [3].
The model development required two steps. The nonlinear coupled differential equations governing this system were solved under the assumption of a steady state. The steady-state concentrations resulting from the steady-state simulation were used in the solution of the linearized set of differential equations describing the sinusoidal steady state. The enzymatic catalysis was treated in terms of two homogeneous reactions, one consuming the glucose oxidase and forming gluconic acid, and the other regenerating the glucose oxidase and forming the peroxide.
References

A. M. Albisser, B. S. Leibel, T. G. Ewart, Z. Davidovac, C. K. Botz, and W. Zingg, Diabetes 23 (1974), 389–396.

J. J. Chamberlain and D. Small, Clin. Diabetes, 26 (2008), 138–139.

V. G. Levich, Physicochemical Hydrodynamics, Prentice Hall, Englewood Cliffs, NJ, (1962), p. 345-357.