[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

This review article aims to provide an updated and comprehensive description of the development of the Electric Current Activated/assisted Sintering technique (ECAS) for the obtainment of dense materials including nanostructured ones. The use of ECAS for pure sintering purposes, when starting from already synthesized powders promoters, and to obtain the desired material by simultaneously performing synthesis and consolidation in one-step is reviewed. Specifically, more than a thousand papers published on this subject during the past decades are taken into account. The experimental procedures, formation mechanisms, characteristics, and functionality of a wide spectrum of dense materials fabricated by ECAS are presented. The influence of the most important operating parameters (i.e. current intensity, temperature, processing time, etc.) on product characteristics and process dynamics is reviewed for a large family of materials including ceramics, intermetallics, metal–ceramic and ceramic–ceramic composites. In this review, systems where synthesis and densification stages occur simultaneously, i.e. a fully dense product is formed immediately after reaction completion, as well as those ones for which a satisfactory densification degree is reached only by maintaining the application of the electric current once the full reaction conversion is obtained, are identified. In addition, emphasis is given to the obtainment of nanostructured dense materials due to their rapid progress and wide applications. Specifically, the effect of mechanical activation by ball milling of starting powders on ECAS process dynamics and product characteristics (i.e. density and microstructure) is analysed. The emerging theme from the large majority of the reviewed investigations is the comparison of ECAS over conventional methods including pressureless sintering, hot pressing, and others. Theoretical analysis pertaining to such technique is also proposed following the last results obtained on this topic.

Consolidation/synthesis of materials by electric current activated/assisted sintering

Damascene copper electroplating for on-chip interconnections, a process that we conceived and developed in the early 1990s, makes it possible to fill submicron trenches and vias with copper without creating a void or a seam and has thus proven superior to other technologies of copper deposition. We discuss here the relationship of additives in the plating bath to superfilling, the phenomenon that results in superconformal coverage, and we present a numerical model which accounts for the experimentally observed profile evolution of the plated metal.

Damascene copper electroplating for chip interconnections

Hydrogen evolution reaction (HER) in alkaline medium is currently a point of focus for sustainable development of hydrogen as an alternative clean fuel for various energy systems, but suffers from sluggish reaction kinetics due to additional water dissociation step. So, the state-of-the-art catalysts performing well in acidic media lose considerable catalytic performance in alkaline media. This review summarizes the recent developments to overcome the kinetics issues of alkaline HER, synthesis of materials with modified morphologies, and electronic structures to tune the active sites and their applications as efficient catalysts for HER. It first explains the fundamentals and electrochemistry of HER and then outlines the requirements for an efficient and stable catalyst in alkaline medium. The challenges with alkaline HER and limitation with the electrocatalysts along with prospective solutions are then highlighted. It further describes the synthesis methods of advanced nanostructures based on carbon, noble, and inexpensive metals and their heterogeneous structures. These heterogeneous structures provide some ideal systems for analyzing the role of structure and synergy on alkaline HER catalysis. At the end, it provides the concluding remarks and future perspectives that can be helpful for tuning the catalysts active-sites with improved electrochemical efficiencies in future.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/advs.201700464

Electrocatalysts for Hydrogen Evolution in Alkaline Electrolytes: Mechanisms, Challenges, and Prospective Solutions

Hybrid supercapacitors with their improved performance in energy density without altering their power density have been in trend since recent years. The hybrid supercapacitor delivers higher specific capacitance in comparison to the existing electric double layer capacitor (EDLC) and pseudocapacitors. Generally, the asymmetric behavior of hybrid supercapacitors which is the combination of EDLC and pseudocapacitor acts as an enhancer in its respective capacitance values. This asymmetric approach marks a new beginning towards the much-needed pollution free, long lasting and proficient energy-storing performance. Corresponding to their utilization in hybrid electric vehicles and similar sort of power necessity based devices; the research in developing new advanced storage devices finds an enormous and vast future ahead. The most significant factor for the energy efficient applications demands a considerably higher ratio of surface to the volume by incorporation of new materials. This review article gives an overview of recent advances in the development of hybrid supercapacitors, storage mechanism, criteria of formation, components, different electrode and electrolyte materials, electrochemical profile assessment, design fabrication and their applications.

A review on recent advances in hybrid supercapacitors: Design, fabrication and applications

By constructing a series of perturbation functions through localization in the Fourier domain and using a symmetric form of the system, we show that the data-to-solution map for the Euler–Poincaré equations is nowhere uniformly continuous in $$B^s_{p,r}(\mathbb {R}^d)$$ with $$s>\max \{1+\frac{d}{2},\frac{3}{2}\}$$ and $$(p,r)\in (1,\infty )\times [1,\infty )$$ . This improves our previous result (Li et al. in Nonlinear Anal RWA 63:103420, 2022) which shows the data-to-solution map for the Euler–Poincaré equations is non-uniformly continuous on a bounded subset of $$B^s_{p,r}(\mathbb {R}^d)$$ near the origin. 

/pdf/on-the-continuity-of-the-solution-map-of-the-euler-poincare-2udt4lzu.pdf

On the Continuity of the Solution Map of the Euler–Poincaré Equations in Besov Spaces

Interface (IF) layers have great influence on the performance of InAs/GaSb type-II superlattice, which can not only balance the strain between adjacent layers, but also change the absorption cutoff wavelength and relative absorption strength. In this study, a modified k·p method based on envelope function approximation is used to theoretically investigate different IF influence on Auger recombination, absorption cutoff wavelength and relative absorption strength. The results of modeling and simulation show that different optical properties can be obtained by different IF.

http://ieeexplore.ieee.org/iel7/7574980/7583073/07583246.pdf

Modeling and simulation of InAs/GaSb type-II superlattices with different interface layers

Copper pillar bump interconnect technology, with its good electrical properties and electromigration resistance, is becoming the next key technology for fine pitch interconnection of chips. The study of the effect of copper pillar bump size on the interfacial diffusion reaction has directive significance to the application of copper pillar bump. This paper focuses on the effect of size on the reliability of copper pillar bump. We use the multi-layer electroplating method to prepare Cu/Sn/Ni copper pillar bump sandwich structure with different diameters of Φ20µm and Φ100µm. We find that the reduction of bump size will promote the growth of interfacial intermetallic compound (IMC). A void growth model in the copper pillar bump is explored by investigating Kirkendall voids and the growth of IMC in Φ20µm Cu/20µmSn/Ni copper pillar bumps.

http://ieeexplore.ieee.org/iel7/7574980/7583073/07583306.pdf

Research on the interfacial reaction and mechanism of Cu/Sn/Ni copper pillar bump

Circularly polarized light (CPL) detection and polarization state recognition are required for a wide range of applications. Conventional polarization detection with optical components causes difficulties for miniaturization and integration. An effective design strategy is proposed for direct CPL detection with chiral material. Here, we realized direct CPL detection based on the combination of chiral photonic cellulose nanocrystal (CNC) and ultraviolet-sensitive ZnO photoconductive material. The CNC layer deposited by evaporation-induced self-assembly established the left-handed chiral nematic structure with a photonic bandgap (PBG) to recognize left-handed CPL (LCPL) and right-handed CPL (RCPL) at specific wavelengths. The PBG of CNC layer has been modulated by the adjustment of chiral nematic pitch to match the semiconductor bandgap of ZnO film in ultraviolet region. The photocurrents under RCPL and LCPL are 2.23 × 10−6 A and 1.77 × 10−6 A respectively and the anisotropy factor Δgpc of 0.23 is acquired for the CPL detection based on the chiral photonic CNC. This design provides a new approach to the detection of CPL polarization state with competitive performance.

Circularly Polarized Light Detection by Chiral Photonic Cellulose Nanocrystal with ZnO Photoconductive Layer in Ultraviolet Region.

In electronic packaging, the interface reaction between solder and substrate directly determines the reliability of the solder joint. An interfacial reaction occurs at the interface between solder and substrate to form an interfacial intermetallic compound (IMC). The growth of the interface IMC has a positive effect on improving the strength of the solder joints, preventing solder diffusion and oxidation, However, if the interface IMC is overmuch, the non-uniform distribution of IMC will adversely affect the performance of the solder joint. Researches have shown that adding nanoparticles to the Sn-Ag-Cu alloy can improve the structure and slow the growth of interfacial IMC, which benefits the performance of the solder. In our work, Sn-3.0Ag-0.5Cu solder was selected as the matrix, and nano-Ag3Sn and Cu3Sn particles were used as additive components. The composite solder paste with different content of nanoparticles was prepared and reflowed. The growth of IMC was observed by Hitachi TM-3000 benchtop scanning electron microscope and FEI Sirion 200 scanning electron microscope (SEM). The morphology of IMC was observed to study the effect of additive nanoparticles on IMC growth. The results show that the addition of 0.3% nano-Ag3Sn and Cu3Sn particles to Sn-3.0Ag-0.5Cu alloy solder can improve the growth of IMC at the solder joint interface, making the IMC morphology of the scallop body shape gentler and more uniform, while adding an excessive amount of Ag3Sn nanoparticles makes the IMC morphology non-uniform.

Ming Li

Papers

On the Continuity of the Solution Map of the Euler–Poincaré Equations in Besov Spaces

Modeling and simulation of InAs/GaSb type-II superlattices with different interface layers

Research on the interfacial reaction and mechanism of Cu/Sn/Ni copper pillar bump

Circularly Polarized Light Detection by Chiral Photonic Cellulose Nanocrystal with ZnO Photoconductive Layer in Ultraviolet Region.

The effect of Ag 3 Sn and Cu 3 Sn nanoparticles on the IMC morphology of Sn-3.0Ag-0.5Cu solder