bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Effect of Centrifugation Method for the Large Particle Removal from CMP Slurry
Authors: Yoo Jinsu , Lee Dongjun , Yoon Hyunjoo , Jeon Joonbae , Kim Kyoungwoo , Hwang Hasub 
Published: February 2020

As device sizes become smaller, to achieve superior flatness which directly related to production yield after CMP (chemical mechanical planarization) process gains more importance.[1]
CMP process is an extensive usage and continuing high growth rates in the semiconductor industry. The scratch due to slurry in large particle is the most challenging issue in CMP process. Even much investigation has been tried to eliminate scratches, the understanding the origins of the scratches during polishing are still needed. [2]
In this study, we examined the change slurry production process to decrease the scratch by centrifugation.
Fig.1 is a comparison of centrifugal separation step added to the slurry production process flow.
Fig.2 shows transmission electron microscope(TEM) image of slurry particle distribution.
Fig.3 shows large particle count(LPC) and quantity filtration measurement(QFM) data we proposed. According to the results, the large particles were removed by centrifugation.
Fig.4 is the scratch comparison result of the normal slurry and centrifuged slurry.
In experimental results, we found that compared and analyzed that the large particles were separated by measuring LPC(large particle count) and QFM(quantity filtration measurement).
We also found out that the centrifuged slurry was improved in CMP through the scratch evaluation.
REFERENCE
1. P. Singer, “Chemical-Mechanical Polishing : A new focus on consumable”, Semiconductor International, pp. 48-53, Feb, 1994.
2. Y. Li, Microelectronic Applications of Chemical Mechanical Planarization, Chap. 17, pp. 512-516, John Wiley & Sons, New Jersey, 2008.
3. J.-G.. Choi et al, “Analysis of scratches formed on oxide surface during chemical mechanical planarization.” Journal of the electrochemical society 157 (2) H186-H191, 2010.

Figure 1
Electrochemical Accesebility of Platinum Nanoparticles Supported on Anatase TiO2 Using Conductive Carbon Additives
Authors: Sato Saiki , Ishida Takanobu , Ayato Yusuke , Mochizuki Dai , Sugimoto Wataru 
Published: February 2020

Degradation of carbon supports at the cathode of polymer electrolyte fuel cells is a critical issue leading to a decrease in activity of the platinum electrocatalysts. Metal oxides based on Ti and Sn have been studied as alternative supports, as they show high stability under severe cathodic conditions.1 However, these metal oxides are typically poorly conductive when compared with carbon support and needs to be either reduced or doped with other metals in order to be able to function as a conducting support. Making an electronically conductive path among nanosized metal oxides with conducting carbon-based materials may offer an alternative approach towards utilization of such non-conducting supports. In this study, we pursued the possibility of utilizing carbon nanotubes (CNTs) as a conducting additive to Pt nanoparticles deposited on non-conducing anatase-type TiO2.
Pt nanoparticles were photo-deposited on anatase-type TiO2 (P25, average particle diameter=25 nm). The amount of platinum on TiO2 was adjusted to be 2 mass%. CNTs were added to a dispersion of Pt/TiO2, adjusted to 20 mass% CNT with respect to Pt/TiO2, and dried to prepare the CNT-Pt/TiO2 composites. The catalyst ink was dropped on a glassy carbon disk electrode (φ= 6 mm, 3.5 µg-Pt cm–2) and dried at room temperature. This electrode was used as the working electrode, and electrochemical studies were conducted with a three-electrode electrochemical cell setup. CO stripping voltammetry in 0.1 M HClO4electrolyte (25°C) was performed in order to estimate the electrochemically active surface area (ECSA) of the platinum nanoparticles.
Figure (a) shows a typical transmission electron microscope (TEM) image of CNT-Pt/TiO2. CNTs form a network-like morphology with Pt/TiO2 particles. The average diameter of platinum nanoparticles determined from 150 particles was 2.9 nm. The specific surface area of the platinum nanoparticles based on the particle size was estimated to be 96 m2 g–1. ECSA was estimated from the oxidation charge of pre-adsorbed CO on platinum surface. The ECSA of CNT-Pt/TiO2 was 63 m2 (g-Pt)–1. Thus, the utilization of the platinum surface was 66% compared with the expected value, i.e. 96 m2 g–1. Although the ECSA of CNT-Pt/TiO2 was lower than Pt/C (83 m2 (g-Pt)–1, platinum particle size of 2.1 nm), the utilization of platinum surface was comparable with that of commercial Pt/C (62%). From these result, it is concluded that an electronically conductive path among platinum supported on TiO2particles was successfully established using a CNT network.
1) K. Sasaki, F. Takasaki, Z. Noda, S. Hayashi, Y. Shiratori, and K. Ito, ECS Trans., 33, 473 (2010).

Figure 1
Investigation of the Sodiation and Desodiation of Hard Carbon By Electrochemical Testing and X-Ray Computed Tomography
Authors: Ledwoch Daniela , Adamson Paul , Brett Daniel J.L , Shearing Paul R. , Kendrick Emma 
Published: February 2020

Since the commercialisation of Sony’s first lithium ion cell in 1990, most battery projects have focused on lithium ion technologies. With the rising number of portable devices and requirement for stationary energy storage technologies to support renewable energy generators, the demand for lithium and therefore its costs will increase. Hence, alternatives have to be found to lower the energy storage costs and reduce the requirement for the limited lithium metal resources [1]. Sodium ion technologies offer a cost and safety advantage over typical lithium ion cells [2,3], and sodium is a much more Earth abundant element. Hard carbon is typically used as the anode for most sodium ion systems. Its intercalation properties with Na differ from those of Li and although research on Na ion batteries and hard carbon has been performed previously [4], further work is required to understand the mechanism and limitations of sodium intercalation and deintercalation in different composite electrodes. The influence of electrode parameters such as tortuosity, porosity and volume changes, need to be investigated in more detail in order to tailor the electrode structure and compositions for a particular property requirement, such as rate or capacity, and hence ultimately, application.
This work is based on a commercial hard carbon material. Composite electrodes have been fabricated and characterised in test cells vs. sodium-metal. The differences in particle size, porosity and volume expansion have been investigated using X-ray computed tomography (CT), SEM imaging and electrochemical testing. The changes in the electrode structures during sodiation and desodiation are correlated to the electrochemical behaviour of the composite electrodes; in particular to the polarisation, self-discharge and apparent diffusion coefficients, as measured using potentiostatic and galvanostatic techniques. The aim of this project is to identify the most important parameters within a composite electrode and their influence on the battery performance characteristics, such as rate capability and cycle life. This will help to engineer electrodes for high rate performance and make them more suitable for high power applications or stationary energy storage systems.
[1] T. Hunt, “Is There Enough Lithium to Maintain the Growth of the Lithium-Ion Battery Market?”, Greentechmedia, 2015, web 14/4/16
[2] V. Palomares, et al., Energy Environ. Sci. 2012, 5, 588
[3] J. Barker, M.Y. Saidi and J. Swoyer, Electrochem. Solid-State Chem. 2003, 6, A1
[4] E. Irisarria, A. Ponroucha, M. R. Palacina, J. Electrochem. Soc. 2015, 14, A2476-2482
Figure 1. a) X-ray computed tomography image of an unsodiated hard carbon electrode; b) cross section of a) - visualising hard carbon (grey), larger spots of carbon black/binder (white) and pores (black); c) SEM of hard carbon electrode.

Figure 1
Facile Synthesis of Low and Non-Precious Metal Nanocatalysts for Oxygen Reduction Reaction in Fuel Cells
Authors: Fu Shaofang , Zhu Chengzhou , Song Junhua , Du Dan , Lin Yuehe 
Published: February 2020

The considerable interest in polymer electrolyte membrane fuel cells (PEMFCs) has sparked sustained research efforts on more active and stable oxygen reduction reaction (ORR) electrocatalyst. Although great progress has been made on ORR catalysts in recent decades, the further development of PEMFCs is severely restrained by high-priced Pt catalysts and the slow kinetics of the ORR on cathode. Control of nanostructures at the atomic level can precisely and effectively tune catalytic properties of catalysts, optimizing the structural and compositional effect and further enabling enhancement in both activity and durability. Therefore, constructing novel nanocatalysts with low and non-Pt group metal (PGM) has received significant attention to further enhance ORR electrocatalytic performance.
Combining structural, morphological and compositional features, Pt-based alloys with optimized composition and unique structures are expected to present enhanced electrocatalytic performance and economical advantages. On one hand, the electron structure of Pt is modified by the non-precious metals when Pt-based alloys are formed. This modification is efficient to weaken the binding energy between Pt and the adsorbed hydroxyl species. Therefore, more active sites are released, and thus improve the electrocatalytic performance. On the other hand, Pt-based nanocrystals with complex morphologies are promising in catalyzing ORR in fuel cells.
The cost of catalyst can be further reduced by completely getting rid of platinum using non-precious metal nanocatalysts or metal-free nanomaterials. In addition, by introducing heteroatoms, metals, and metal oxides, more active sites are formed for oxygen reduction reactions, and thus improve the catalytic performance of the catalysts.
Significantly, these low and non-precious metal nanocatalysts show excellent electrocatalytic activity and high stability toward to the ORR, holding great promise for the development of PEMFCs.
Rechargable Lithium-Air Batteries: Investigation of Redox Mediators Using DEMS
Authors: Christensen Mathias Kjærgaard , Storm Mie Møller , Norby Poul 
Published: February 2020

The rechargeable aprotic lithium-air battery is a promising technology that offers high theoretical energy density of as much 10 times the capacity of current Li-ion batteries. This type of battery technology differs from conventional batteries because of the gas exchange during discharge/charge cycling. Characterizing the gas content during charge using Differential Electrochemical Mass Spectroscopy (DEMS) allows for in-situ characterization of chemistry in the battery.
Using our DEMS setup we have investigated different cathode materials for lithium-air batteries. A carbon black cathode exhibits a flat discharge curve with low over-potentials until the "sudden death" phenomenon which causes the voltage to drop quickly. On the charge side however, this materials exhibits significant over-potentials. These high over-potentials are linked with CO2 development which indicates that the cathode material or electrolyte is being decomposed. This is also seen with Thermally reduced Graphene Oxide (TrGO). The graphene based cathode is interesting as it exhibits a high surface area which in turn increases capacity.
Using the additive LiI, functioning as a redox mediator, the discharge curve remains largely unchanged whilst the charge curve exhibits dramatically lower over-potential, throughout the experiment [1][2]. Under certain conditions the chemistry of the battery changes, resulting in a four electron process that produces the reversible discharge product LiOH rather than Li2O2 which is observed without the redox mediator [2]. This results in higher energy densities and ideally higher cyclability due to the lower over-potentials. Using DEMS we have investigated the gas evolved in the process to determine the electron to oxygen ratio using both cathode materials mentioned.
As has been shown with lithium-air batteries the water content affects the morphology of the discharge product[3]. The effect of changing experimental conditions such as varying water content will be reported.

References

[1] Hee Dae Lim, Hyelynn Song, Jinsoo Kim, Hyeokjo Gwon, Youngjoon Bae, Kyu Young Park, Jihyun Hong, Haegyeom Kim, Taewoo Kim, Yong Hyup Kim, Xavier Lepro, Raquel Ovalle-Robles, Ray H. Baughman, and Kisuk Kang. Superior rechargeability and efficiency of lithium-oxygen batteries: Hierarchical air electrode architecture combined with a soluble catalyst. Angewandte Chemie - International Edition, 53(15):3926{3931, 2014.
[2] Tao Liu, Michal Leskes, Wanjing Yu, Amy J. Moore, Lina Zhou, Paul M. Bayley, Gunwoo Kim, and Clare P. Grey. Cycling Li-O2 batteries via LiOH formation and decomposition. Science, 350(6260):530{533, 2015.
[3] Nagaphani B. Aetukuri, Bryan D. McCloskey, Jeannette M. Garca, Leslie E. Krupp, Venkatasubramanian Viswanathan, and Alan C. Luntz. Solvating additives drive solution-mediated electrochemistry and enhance toroid growth in non-aqueous Li-O2 batteries. Nature Chemistry, 7(January):50-56, 2015.
Estimation of the Cathodic Overpotential for the Double Layer Structure in Pemfcs Using MD
Authors: Nuñez Toledo Laura Elisa , Ribadeneira Paz Rafael Esteban 
Published: February 2020

In this work a molecular dynamics (MD) based model is employed to describe and obtain the over-potential in the EDL cathodic structure consisting of the platinum(100)-water-oxygen interface, for Proton Exchange Membrane Fuel Cells (PEMFCs). This approach aims to be integrated in a multiscale model [1], describing the kinetics in the cathodic electrode through density functional theory (DFT) and the macroscopic behavior through a pseudo 2D model for PEMFCs reported in previous works [1]. In the framework of MD simulations, it is required to define an interaction potential model that describes the size, the charge polarization and the chemical characteristics of the electrochemical interface. In this work TIP3P model is used to describe interaction among water molecules, whereas interaction among platinum, water and oxygen is modeled with Lennard-Jones 12-6 model including electrostatic interactions. MD simulations are performed in LAMMPS with a rigid wall of platinum and periodic boundary conditions in x and y directions, using a NPT ensemble to obtain the equilibrium configuration of the system at 1 bar and 353.15K
The MD simulation allows to obtain the density distribution functions of water molecules and oxygen atoms perpendicular to X-Y plane. Then, the density distribution profiles are used to calculate the charge distribution through formal charge of water and oxygen. Finally the Poisson equation is employed to get the electrostatic potential across the interface and an associated electrostatic over-potential. Also several simulations are carried out at different cathodic current densities. The obtained water density distribution at OCV is validated according to the results of previous works [2-4].
[1] S. Castaneda Ramirez, a. E. Perez Mendoza, és R. E. Ribadeneira Paz, ECS Trans., 66, 19–39 (2015).
[2] X. Xia, L. Perera, U. Essmann, és M. L. Berkowitz, Surf. Sci., 335, 401–415 (1995).
[3] K. Foster, K. Raghavan, és M. Berkowitz, Chem.
Phys. Lett., 162, 32–38 (1989).
[4]E. Spohr, J. Phys. Chem., 93, 6171–6180 (1989).
[5] K. Heizinger, Pure and appl Chem.
63, 1733-1742 (1991).
[6] D. A. Rose, I. Benjamin. J. Phys. Chem
95 (1991).
Praseodymium Doped Ceria Oxygen Surface Exchange Coefficient and Film Stress Measurements Via the Curvature Relaxation Technique
Authors: Ma Yuxi , Nicholas Jason D. 
Published: February 2020

Introduction

Praseodymium doped ceria (PCO) is a mixed ionic electronic conductor (MIEC) that can be used as a cathode material in solid oxide fuel cells (SOFCs). Under SOFC operating conditions, PCO undergoes the following reaction [1]:
½ O2 + 2Pr’
Ce + VӦ à 2PrCe + Oo
x

The kinetics of this oxygen exchange reaction are represented by the oxygen surface exchange coefficient (kchem
). In this work, simultaneous kchem
and stress measurements on PCO thin films atop yttria-stabilized zirconia (YSZ) substrates were performed from 625-725 oC using the curvature relaxation (κR) technique.

Experimental Methods

Phase pure Pr0.1Ce0.9O1.95 powder was prepared through glycine nitrate combustion and subsequent powder calcination in air. (001) oriented 9.5% YSZ substrates (Crystec, GmbH) were pre-annealed at 1450oC for 20 hours. PCO thin films were sputtered onto YSZ substrates at room temperature and then sintered for 1 hour at 1100oC. The bilayer structures were tested using a multi beam optical stress sensor (MOSS) from 625oC to 725oC with 25oC increments. The κR technique determines kchem
by fitting a solution of Fick’s 2nd Law to the curvature response of mechano-chemically active film | inert substrate bilayers reacting to sudden changes in oxygen partial pressure (synthetic air (21% O2 - 79% Ar) and 10% synthetic air - 90% Ar) [2,3]. Film stress values were calculated using Stoney’s equation [2,3]. In order to compare the kchem
values with those in the literature, electrically-measured PCO kq
values from the literature [4] were turned into kchem
values by multiplying them by the corresponding PCO thermodynamic factor from Ref [5].

Results

Figure 1 shows how the kchem
value measured via the κR technique compares with literature [4,5] values.

Conclusions

The PCO kchem
and activation energies measured here are significantly different than those reported in the literature. Although additional work is needed before these effects can be explained in full, these discrepancies may be caused by the different synthesis techniques (sputtering vs. pulsed laser deposition) used to produce the two films shown in Figure 1.

Acknowledgements

This material is based upon work supported by the Department of Energy under Award Number DE-FE0023315.

References

[1] Bishop S R, Stefanik T S, Tuller H L. Journal of Materials Research, 2012, 27(15): 2009-2016.
[2] Yang Q, Burye T E, Lunt R R, et al. Solid State Ionics, 2013, 249: 123-128
[3] Yang Q, Nicholas J D. Journal of the Electrochemical Society, 2014, 161(11): F3025-F3031.
[4] Chen D, Bishop S R, Tuller H L. Journal of Electroceramics, 2012, 28(1): 62-69.
[5] Chen D, Bishop S R, Tuller H L. Advanced Functional Materials, 2013, 23(17): 2168-2174.

Figures

Figure 1. A comparison of literature and κR-measured PCO kchem
values [4,5].

Figure 1
Bipolar Membrane Fabrication for Hybrid Acid/Alkaline Fuel Cell Systems
Authors: Ahlfield John M. , Liu Lisha , Kohl Paul A 
Published: February 2020

Bipolar membranes fuel cells utilizing both anion and cation conductive materials have several advantages compared to their purely acidic or alkaline counterparts. The potential advantages include improved water management through self-hydration and facile electrode kinetics. Material transport properties play an important role in determining viability of membrane and ionomer materials. In addition, the cation-anion junction itself is a critical element in determining device performance because it must be sufficiently conductive to ionic species and mechanically stable to withstand the internal pressure from water formation. A series of electrochemical devices using different bipolar membranes have been fabricated for use in direct methanol and hydrogen fuel cells. This study examines both single- and two-membrane systems containing cation-anion junctions. These fuel cells were characterized by performance metrics and electrochemical impedance spectroscopy to determine specific areas for improvement in the bipolar devices. Operation under varying humidity was studied in order to understand water management necessary for bipolar fuel cells. These results will be used in the future optimization of bipolar devices.
Financial support from US Office of the Deputy Assistant Secretary of the Army for Defense Exports and Cooperation (DASA-DE&C) is gratefully acknowledged.
Bond Order Potential for Two-Dimensional Stanene to Probe Thermal Transport Using Molecular Dynamics Simulations
Authors: Narayanan Badri , Cherukara Mathew , Kinaci Alper , Sasikumar Kiran , Sen Fatih G. , Davis Michael J. , Gray Stephen K. , Chan Maria K. Y. , Harder Ross , Sankaranarayanan Subramanian K. R. S. 
Published: February 2020

Recent realization of single layer tin (stanene) on Bi2Te3 substrate via molecular beam epitaxy has led to a surge in research into its fundamental properties, and the feasibility of using stanene for various energy and device applications. In particular, stanene has attracted lot of attention owing to its tremendous promise in topological insulation, large-gap 2D quantum spin hall states, lossless electrical conduction, enhanced thermoelectricity, and topological superconductivity. Most of the previous works on stanene have focused on its electronic properties; atomistic investigations on growth mechanisms (needed to guide synthesis), phonon transport (crucial for designing thermoelectrics), and thermo-mechanical behavior of stanene are scarce. This paucity is primarily due to lack of reliable and efficient potential models that can accurately capture atomic interactions in stanene. Here, we develop a bond-order potential (BOP) based on Tersoff formalism that can accurately capture bond breaking/formation events, structure, energetics, thermodynamics, phonon frequencies, thermal conductivity, and mechanical properties of single layer tin. We determine the BOP parameters by fitting to a training dataset containing (a) structure, (b) equation of state (energy vs area), (c) elastic constants, and (d) phonon dispersion of stanene obtained from our density functional theory calculations. For fitting, we employ a global optimization scheme based on genetic algorithms. Finally, we employed our newly developed BOP to study anisotropy in thermal conductivity of stanene sheets, temperature induced rippling, as well as dependence of anharmonicity and thermal conductivity on temperature.
Figure Caption: Comparison of (a) phonon dispersion, and (b) phonon density of states for monolayer stanene predicted by our newly developed Tersoff potential with those obtained from density functional theory calculations

Figure 1