bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) Grain Boundaries and Dislocations in Layered Cathodes
Authors: Xu Zhengrui , Lin Feng 
Published: July 2021

Crystallographic defects exist in many redox active energy materials, e.g., battery and catalyst materials, which significantly alter their chemical properties for energy storage and conversion. In this presentation, we will address how these defects, e.g., grain boundaries and geometrically necessary dislocations, govern the charge distribution and battery performance of layered oxide cathodes.
Architecting grain crystallographic orientation can modulate charge distribution and chemomechanical properties for enhancing the performance of polycrystalline battery materials. However, probing the interplay between charge distribution, grain crystallographic orientation, and performance remains a daunting challenge. Herein, we elucidate the spatially resolved charge distribution in lithium layered oxides with different grain crystallographic arrangements and establish a model to quantify their charge distributions. While the holistic “surface-to-bulk” charge distribution prevails in polycrystalline particles, the crystallographic orientation-guided redox reaction governs the charge distribution in the local charged nanodomains. Compared to the randomly oriented grains, the radially aligned grains exhibit a lower cell polarization and higher capacity retention upon battery cycling. The radially aligned grains create less tortuous lithium ion pathways, thus improving the charge homogeneity as statistically quantified from over 20 million nanodomains in polycrystalline particles. This study provides an improved understanding of the charge distribution and chemomechanical properties of polycrystalline battery materials.
Crystallographic defects, such as geometrically necessary dislocations, are reported to influence the redox reactions in battery particles through single-particle, multimodal, in situ synchrotron measurements. Through Laue X-ray microdiffraction, many crystallographic defects are spatially identified and statistically quantified from a large quantity of diffraction patterns in many layered oxide particles, including geometrically necessary dislocations, tilt boundaries, and mixed defects. The in situ and ex situ measurements, combining microdiffraction and X-ray spectroscopic imaging, reveal that LiCoO2 particles with a higher concentration of geometrically necessary dislocations provide deeper charging reactions, indicating that dislocations may facilitate redox reactions in layered oxides during initial charging. The present study illustrates that a precise control of crystallographic defects and their distribution can potentially promote and homogenize redox reactions in battery materials.
Capturing Material Heterogeneities Effects on the Electrochemical Impedance of Li(Ni1-x-yMnxCoy)O2-Based Cathodes through 4D-Resolved Physical Simulations
Authors: Shodiev Abbos , N. Primo Emiliano , Chouchane Mehdi , Lombardo Teo , Ngandjong Alain C. , A. Franco Alejandro 
Published: July 2021

Electrochemical impedance spectroscopy (EIS) is a widely used technique for the characterization of Lithium Ion Battery (LIB) porous electrodes, and to extract their tortuosity factors in particular, using transmission line models supported on homogenizations and oversimplifications of the actual electrode texture Here we use our a 4D (3D in space + time) physical model to simulate EIS carried out on NMC porous cathodes, derived from the simulation of their manufacturing process, in symmetric cells.[1]
The calculations of EIS spectra on the manufacturing model-calculated porous electrodes (in a symmetric cell configuration) were done in a diluted electrolyte regime by explicit consideration of the spatial location of active material, carbon and binder domain (CBD) and pore phases, with distinctive physics for each of them.2 The calculated impedance responses are compared with our experimental results arising from NMC-based cathodes prepared in a similar way. The possibility to tune the physical properties of each phase in our 4D model allowed us to identify the different contributions to the EI spectra shapes. We found that for NMC-based cathodes there is a complex interplay between the solid and ionic conductivities, which affects the characteristic times at which each region of the porous electrode is accessed as a function of the frequency. Furthermore, we found that electrode inhomogeneities related to the spatial CBD location results in highly inhomogeneous impedance behaviors. We observe that these effects strongly depend on the electrode formulation and other manufacturing parameters, such as the electrode calendering. We believe that our 4D model constitutes a powerful tool to assess EI spectra beyond the limitations of traditional transmission line models.

Shodiev, Abbos, Primo, Emiliano N., Chouchane, Mehdi, Lombardo, Teo, Ngandjong, Alain C., Rucci, Alexis & Franco, Alejandro A. 4D-resolved physical model for Electrochemical Impedance Spectroscopy of Li(Ni1-x-yMnxCoy)O2-based cathodes in symmetric cells: Consequences in tortuosity calculations. J. Power Sources (2020). 227871 doi:10.1016/j.jpowsour.2020.227871

Chouchane, Mehdi, Rucci, Alexis, Lombardo, Teo, Ngandjong, Alain C. & Franco, Alejandro A. Lithium ion battery electrodes predicted from manufacturing simulations : Assessing the impact of the carbon-binder spatial location on the electrochemical performance. J. Power Sources (2019). 444, 227285

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Isotropic Atomic Layer Etching in High Aspect Ratio Structures
Authors: Fischer Andreas , Lemaire Paul , Routzahn Aaron , Lill Thorsten 
Published: July 2021

Isotropic Atomic Layer Etching can be used to remove materials such as high-k oxides or certain metals from high aspect ratio (HAR) structures from sidewalls and even non-line-of-site locations where access via reactive ion etching would be challenging or impossible. Those locations could be sites below the shelves in 3D-NAND stacks or around wires in GAA structures.
The etch rate per cycle of Thermal Isotropic ALE should in principle be insensitive to aspect ratio and line-of-sight accessibility if both reaction steps are fully saturated. Deviations from the ideal behavior have been reported previously for Al2O3 ALE with alternating HF and DMAC cycles [1]. Without mitigation, this behavior would ultimately lead to performance differences in devices located at the bottom of the structure compared to those at the top.
In this work we present a method to counteract the unwanted depth dependence of the etch rate when etching HfO2 with the HF/DMAC ligand exchange ALE process. To mitigate the depth dependence, we explored the use of operating the ALE process at ultra-high pressures up to 5 Torr and over a wide temperature range. We found that under these conditions, the modification step has been boosted such that it takes place near its saturation regime so that top-to-bottom etch rate differences could be reduced. We show that high pressure and temperature mostly target the fluorine profile along a structure and removal step times needed to be allowed sufficient time to clear the entire modified layer. We give an example of such application in a 50:1 aspect ratio 3D NAND test structure.
Holistic Integrated Process Solutions for Patterning Phase Change Memory Devices
Authors: Hoang John , Shen Meihua , Lill Thorsten , Qian Danna , Routzahn Aaron , Chen Jack , Altieri Nick , Yu Anthony , Dulkin Alexander , Sims Jim , McKerrow Andrew , Dylewicz Rafal 
Published: July 2021

Phase change materials (PCM) have emerged as the leading candidate for next generation non-volatile storage class memory as demonstrated by the commercialization of 3D Cross Point memory. More recently, PCM memories have been explored for non-von Neumann system architectures with potential applications in neuromorphic computing. To accelerate the widespread adoption of PCM technology, better understanding of the unit processes and its interactions is needed to cost effectively produce high fidelity PCM devices.
Challenges in creating cross point PCM architectures are significantly different from more dominant technologies such as DRAM and 3DNAND. From a device perspective, the PCM composition is sensitive to crystallization temperature, which translates to potentially large changes in the switching resistance for small changes in composition. From a material perspective, phase change chalcogenides readily etch in various plasma etch chemistries with the many etch chemistries exhibiting bulk composition changes. Furthermore, slight changes in the PCM composition can be removed by wet clean. In this regard, one of the main process challenges is to not etch chalcogenides laterally in order to maximizing the device volume. Finally, from a structural perspective, PCM are relatively soft with Young’s modulus that can be 3x smaller than materials found in DRAM/3DNAND stacks (e.g. Si, SiOx). Soft chalcogenides can lead to increased line bending, especially when the chalcogenide is at the bottom of the stack. As a result, post wet clean pattern collapse and line bending from film stress can be challenging to manage.
To meet the material and structural challenges, we developed an integrated system combining dry etch, wet clean, and deposition process modules. Comprehensive understanding of each process module as well as the interactions of different process modules has been obtained. We will present some holistic process solutions combining dry etch, wet clean, and deposition to deliver collapse free, high fidelity PCM structures.
Mechanical and Optical Properties of Amorphous SiN-Based Films Prepared By ECR PECVD and CCP PECVD
Authors: Ahammou Brahim , Abdelal Aysegul , Levallois Christophe , Landesman Jean-Pierre , Mascher Peter 
Published: July 2021

Hydrogenated amorphous silicon nitride (a-SiN:H) and silicon carbonitride (a-SiCN:H) films grown by plasma enhanced chemical vapor deposition (PECVD) are widely investigated for their interesting optical and electrical properties [1]. In this work, we discuss the effect of the deposition power on SiN-based films during plasma deposition. The influence on the optical and mechanical properties of the films was investigated. In order to study this issue on a broader basis, two types of plasmas were applied to deposit 0.5 to 1.5 μm a-SiN:H and a-SiCN:H films. First, a-SiN:H and a-SiCN:H films were deposited by electron cyclotron resonance (ECR) PECVD using the same deposition parameters for all films. During the deposition process, the carbon content in the a-SiCN:H thin films was introduced into the chamber through a pure CH4 gas source to avoid any perturbation on the deposition pressure. Second, a-SiN:H films were deposited by a capacitively coupled plasma reactor CCP PECVD using a SiH4/NH3/N2/Ar precursor mixture. In both deposition processes, the ion bombardment energy was tuned only by the deposition power. The mechanical properties of the films were determined ex-situ by profilometry to evaluate the residual stress using the wafer curvature method and by nanoindentation to determine Young’s modulus and hardness of the films. The thickness and the refractive index were measured by variable angle spectroscopic ellipsometry (VASE). It was observed that the evolution of the residual stress according to the deposition power in the ECR PECVD was different from the CCP PECVD. Besides, we notice a slight increase in the refractive index when the residual stress becomes more compressive as illustrated in figure 1 for a-SiN:H and a-SiCN:H films. Through this discussion, we try to have a better understanding of the different interactions taking place when the deposition power increases in terms of ion bombardment energy. Then, we will study the effect of ion bombardment on the film structure based on the composition and structure of the films and the hydrogen bond concentration measured by Fourier transmission infrared spectroscopy (FTIR). In addition, we have also investigated the influence of carbon incorporation on a-SiN:H thin film properties. We notice a decrease in the refractive index and an increase in the compressive residual stress caused by the carbon incorporation.
[1] A. Abdelal, Z. Khatami, and P. Mascher, “Optical and Electrical Properties of ECR-PECVD Grown SiCN Thin Films,” ECS Meet. Abstr., vol. MA2018-01, no. 17, p. 1189, Apr. 2018, doi: 10.1149/ma2018-01/17/1189.

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(Invited) Nitrogen Fixation Using Non Thermal Atmospheric Plasma (over water) : Challenges and Perspectives
Authors: Maira Nicolas , Remy Antoine , Pattyn Cedric , Roy Nepal Chandra , Reniers François 
Published: July 2021

Nitrogen fixation, i.e. the transformation of molecular nitrogen into nitrates or ammonia is a major industrial process. The Haber-Bosch and the Ostwald processes are at the origin of the massive increase of yield of food production, contributing to the development of modern agriculture. However, despite the fact that these processes are exothermic, the need to operate at high temperature for kinetic reasons, the necessity to start (most often) from natural gas as a source of hydrogen, and the industrial plants located far away from the end user, make these industrial processes huge producers of CO2.
Historically, the Birkeland-Eyde process, however, allow to fix nitrogen using arc plasma. The energy yield of this process being small, it was replaced by the Haber-Bosch process. With the development of low temperature, non thermal plasmas processes, there is nowadays a hope to develop local, low energy cost, nitrogen fixation reactors, with only air as reactant. For food and agriculture applications, especially for urban agriculture, a possible approach is to generate nitrates directly inside the water that feeds the plants. The talk will present a few non thermal atmospheric plasma setups than can be used for nitrogen fixation. In a first setup, nitrogen oxides are generated directly in a dielectric barrier discharge (DBD) filled with various proportions of nitrogen and oxygen. In a second setup, one of the dielectrics is replaced by water. In a third setup, a DC microplasma is lighted up between a metallic electrode and a water solution, containing an electrolyte. In this last setup, a counter electrode closes the electrical circuit, making it resembling a electrochemical cell. In this last setup, two configurations are tested, by changing the polarity of the two electrodes.
For all the setups, the amount of various nitrogen oxides formed in the gas phase as a function of the experimental parameters is studied using optical emission spectrometry, infrared spectrometry and mass spectrometry. Similarly, the composition of the liquid phase is analyzed using ionic chromatography and specific reagents tests. Correlations between a) the gas phase composition and b) the liquid phase composition are established. The role of OH radicals (in the gas phase) and hydrogen peroxide (in the liquid phase) on the relative amounts of nitrites and nitrates is evidenced. For the microplasma experiments, it is shown that inverting the polarity of the electrodes lead to drastic changes in the yields of the species produced. From all these results, potential mechanisms will be presented, and future challenges will be open to discussion.
(Invited) Controlling Synthesis and Functionalization of Anisotropic Gold Nanoparticles for Applications in Biology
Authors: Fabris Laura 
Published: July 2021

Anisotropic gold nanoparticles, such as, for instance, nanorods and nanostars, have been integrated in many areas of biomedical research, including, but not limited to, imaging, sensing, and therapy. While the use of gold has remained relatively consistent due to, primarily, its biocompatibility, the choice of morphology to employ has depended on the intended application. Regardless of the application, attention must be paid toward the definition of best practices for the synthesis, functionalization, and characterization of nanoparticles, especially when they need to be interfaced with the biological milieu.
In my talk, I will report on our recent observations concerning the design of gold nanostars to target the biologically transparent window of the electromagnetic spectrum, the optimization of synthetic monodispersity to improve single cell applicability, and the careful control of relevant bioconjugation steps that need to be implemented to realize functional intracellular biosensors. I will focus in particular on the synthesis of highly monodispersed gold nanostars with resonant bands extending up to 2000 nm, on the use of surfactant free nanostars for the design of surface enhanced Raman spectroscopy (SERS) nanoprobes for the stratification of prostate cancer patients, and the use of tunable silica shell to increase stability of the nanostars while also enhancing their SERS response. I will also report on the effect of the protein corona on the performance of fluorescent flares and SERS beacons for the identification and quantification of influenza A virus (IAV) RNA both in buffer and in individual intact cells.
Despite the broad applicability of anisotropic gold nanoparticles, often a complete understanding of their properties and the steps needed to reproducibly and accurately achieve them is lacking. Due to the intrinsic complexity of the biological milieu, the consistency of the probes used to understand it is even more imperative and thus requires even more synthetic control. I will therefore, in conclusion, present some tips and guidelines that will hopefully stimulate an interactive conversation on the topic.
(Invited) Effects of Coordination Structure of Silicon Ions on Electrodeposition Process of Silicon in Fluoride Melts
Authors: Suzuki Yuta , Fukunaka Yasuhiro , Goto Takuya 
Published: July 2021

Silicon electrodeposition in molten salts is a key technology for fabricating silicon films, as a material for solar cells, by environmentally friendly and inexpensive processes. We have already reported the electrodeposition of silicon films from SiO2 in fluoride melts. However, there are only few studies about the effects of ions in fluoride melts, such as O2- anion, and Li+/Na+/K+ cations, on silicon electrodeposition processes. In particular, it is important to understand the coordination structure of silicon ions for controlling the nucleation and growth processes between solid metal substrates and fluoride melts interface.
In this study, we investigated the electrodeposition of silicon from SiO2 in LiF-NaF-KF melts mixed with Li2O as a source of O2- anion at 873 K, and binary LiF-KF, LiF-NaF, and NaF-KF melts. The results of the in-situ Raman spectroscopy and DFT calculations indicated that the O2− anions could cleave the Si-O-Si bonds of SiO2 or silicate ions such as [Si2O5]2−; consequently, the formation of tetrahedron [SiO3F]3− species was promoted. Furthermore, the reduction currents, attributed to the reduction of Si ions, increased significantly by the addition of Li2O; moreover, the thickness and current efficiency of the electrodeposited polycrystalline Si layer prepared by potentiostatic electrolysis was improved. This study suggested the design of the molten salts bath was significant for controlling interfacial phenomena at electrode/molten salts to fabricate high-quality Si layers.
Understanding the Relationship between State-of-Charge and Structural Fragility in Ni-Rich Layered Materials for Lithium Batteries
Authors: Waters Crystal K. , Lin Feng 
Published: July 2021

Lithium batteries are at the frontier of energy storage. Co-free, Ni-rich layered transition metal oxide (TMO) materials have gained interest within the past decade due to their low cost and increased practical capacity. The challenge with employing these layered oxide cathodes is their inherent structural fragility, facilitated by metal cation migration and lattice oxygen loss. Upon charging, the redox center becomes oxidized, generating thermodynamically favorable electron transfer pathways between the electrolyte and the layered oxide. This transfer pathway is mainly due to the TM3d-O2p orbital hybridization perturbation during battery charging.
Surface reconstruction and the structural reordering that accompanies it can undesirably influence the cathode – electrolyte interphase, leading to enhanced electrolyte degradation pathways that can minimize Coulombic efficiency. Electrolyte decomposition occurs at the oxide cathode surface, but can lead to bulk electronic and structural changes of the layered oxide, chemomechanical breakdown, and irreversible phase transformations.
In this study, we focus on understanding the interplay between bulk phase transitions and surface instability with respect to electrolyte chemical decomposition. We use novel galvanostatic cycling parameters, extensive electron microscopy, and synchrotron X-ray techniques to decouple chemical and electrochemical electrolyte decomposition pathways to understand their role in Co-free, Ni-rich oxide cathode degradation. This work allows us to decouple surface and bulk chemistries at the cathode – electrolyte interphase to inform further insight into optimal Ni-rich oxide cathode design.
(Invited) Towards Model-Based Predictive Battery Electrode Design
Authors: Krewer Ulrike , Witt Daniel , Schmidt Oke , Röder Fridolin 
Published: July 2021

Lithium ion batteries contain porous electrodes, whose design determines battery performance, cost and life-time.
Yet, we are far from knowing what is the best structure, and it is prohibitively time- and resource-consuming
to do experimental trial and error production, as there are too many parameters in the production process and in the electrode itself.
This motivates to use physico-chemical models that yield insight into performance and limitations of given electrode structures as well as
allow optimal design. The need for models that allow structure optimisation, i.e. rapid evaluation of many design variants, basically excludes large 3-dimensional models with complex inhomogeneous structures. On the other hand, homogeneous pseudo-two-dimensional models face limitations regarding the prediction of new electrode designs as the crucial influence of conducting additives and binder are not considered sufficiently.
This talk will elucidate a pathway that allows model-based predictive battery design.
It shows the application of microstructure models to identify the effective electric and ionic conductivity and electroactive area of
electrode structures containing additives, and the transfer of this knowledge via surrogate models into electrochemical P2D models to evaluate the respective electrochemical performance. The effect of additive and active material content and distribution is demonstrated at the example of Li ion battery cathode and all solid state Li battery electrodes. The models are applicable to predict the performance of electrodes in cells. We further elucidate how uncertainties in the production process of electrodes lead to distributed electrode design parameters and performance.
Finally, we show and compare two pathways of identifying optimal electrode designs at the example of dual layer electrodes: a coarse-grained scanning of thousands of design variants using 8 parameters reveals strongly different designs for optimal charge and discharge, whereas a high resolution optimisation of two design parameters shows flat performance plateaus.
Model-based design optimization without extensive experimental studies will reduce costs and experimental efforts in the development of next-generation batteries.