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Science and Technology of Advanced Materials

Chaolin Tan, Kesong Zhou, Wenyou Ma, Bonnie Attard, Panpan Zhang, Tongchun Kuang
Selective laser melting (SLM) additive manufacturing of pure tungsten encounters nearly all intractable difficulties of SLM metals fields due to its intrinsic properties. The key factors, including powder characteristics, layer thickness, and laser parameters of SLM high density tungsten are elucidated and discussed in detail. The main parameters were designed from theoretical calculations prior to the SLM process and experimentally optimized. Pure tungsten products with a density of 19.01 g/cm3 (98.50% theoretical density) were produced using SLM with the optimized processing parameters...
2018: Science and Technology of Advanced Materials
Samy Almosni, Amaury Delamarre, Zacharie Jehl, Daniel Suchet, Ludmila Cojocaru, Maxime Giteau, Benoit Behaghel, Anatole Julian, Camille Ibrahim, Léa Tatry, Haibin Wang, Takaya Kubo, Satoshi Uchida, Hiroshi Segawa, Naoya Miyashita, Ryo Tamaki, Yasushi Shoji, Katsuhisa Yoshida, Nazmul Ahsan, Kentaro Watanabe, Tomoyuki Inoue, Masakazu Sugiyama, Yoshiaki Nakano, Tomofumi Hamamura, Thierry Toupance, Céline Olivier, Sylvain Chambon, Laurence Vignau, Camille Geffroy, Eric Cloutet, Georges Hadziioannou, Nicolas Cavassilas, Pierre Rale, Andrea Cattoni, Stéphane Collin, François Gibelli, Myriam Paire, Laurent Lombez, Damien Aureau, Muriel Bouttemy, Arnaud Etcheberry, Yoshitaka Okada, Jean-François Guillemoles
Photovoltaic generation has stepped up within the last decade from outsider status to one of the important contributors of the ongoing energy transition, with about 1.7% of world electricity provided by solar cells. Progress in materials and production processes has played an important part in this development. Yet, there are many challenges before photovoltaics could provide clean, abundant, and cheap energy. Here, we review this research direction, with a focus on the results obtained within a Japan-French cooperation program, NextPV, working on promising solar cell technologies...
2018: Science and Technology of Advanced Materials
Yu-Kyoung Kim, Kwang-Bok Lee, Seo-Young Kim, Ken Bode, Yong-Seok Jang, Tae-Young Kwon, Moo Heon Jeon, Min-Ho Lee
Magnesium alloys are biodegradable metals receiving increasing attention, but the clinical applications of these materials are delayed by concerns over the rapid corrosion rate and gas formation. Unlike corrosion, which weakens mechanical properties, the gas formation issue has received little attention. Therefore, we evaluated the gas formation and biological effects for Mg implants through preclinical (immersed in Earle's balanced salt solution and in vivo ) and clinical studies. The immersion test examined the gas volume and composition...
2018: Science and Technology of Advanced Materials
Chikako Sano, Hiroyuki Mitsuya, Shimpei Ono, Kazumoto Miwa, Hiroshi Toshiyoshi, Hiroyuki Fujita
A novel triboelectric energy harvester has been developed using an ionic liquid polymer with cations fixed at the surface. In this report, the fabrication of the device and the characterization of its energy harvesting performance are detailed. An electrical double layer was induced in the ionic liquid polymer precursor to attract the cations to the surface where they are immobilized using a UV-based crosslinking reaction. The finalized polymer is capable of generating an electrical current when contacted by a metal electrode...
2018: Science and Technology of Advanced Materials
Martin Neukom, Simon Züfle, Sandra Jenatsch, Beat Ruhstaller
We present an overview of opto-electronic characterization techniques for solar cells including light-induced charge extraction by linearly increasing voltage, impedance spectroscopy, transient photovoltage, charge extraction and more. Guidelines for the interpretation of experimental results are derived based on charge drift-diffusion simulations of solar cells with common performance limitations. It is investigated how nonidealities like charge injection barriers, traps and low mobilities among others manifest themselves in each of the studied cell characterization techniques...
2018: Science and Technology of Advanced Materials
Katsuya Iwaya, Takeo Ohsawa, Ryota Shimizu, Yoshinori Okada, Taro Hitosugi
The interfaces of complex oxide heterostructures exhibit intriguing phenomena not observed in their constituent materials. The oxide thin-film growth of such heterostructures has been successfully controlled with unit-cell precision; however, atomic-scale understandings of oxide thin-film surfaces and interfaces have remained insufficient. We examined, with atomic precision, the surface and electronic structures of oxide thin films and their growth processes using low-temperature scanning tunneling microscopy...
2018: Science and Technology of Advanced Materials
Qingqing Sun, Koki Kanehira, Akiyoshi Taniguchi
Nanoparticles (NPs) elicit various physiological responses in cellular environment, and the effect of NPs on cell migration is of high interest. In this work, the effects of NPs on cell migration and their possible mechanisms were studied. Here, we showed that after exposure to pegylated titanium dioxide nanoparticles (TiO2 -PEG NPs, where PEG stands for the polyethylene glycol), NCI-H292 cells exhibited slower migration than control cells. Furthermore, larger NPs inhibited cell migration much stronger than smaller NPs...
2018: Science and Technology of Advanced Materials
Thomas Feurer, Benjamin Bissig, Thomas P Weiss, Romain Carron, Enrico Avancini, Johannes Löckinger, Stephan Buecheler, Ayodhya N Tiwari
Multi-junction solar cells show the highest photovoltaic energy conversion efficiencies, but the current technologies based on wafers and epitaxial growth of multiple layers are very costly. Therefore, there is a high interest in realizing multi-junction tandem devices based on cost-effective thin film technologies. While the efficiency of such devices has been limited so far because of the rather low efficiency of semitransparent wide bandgap top cells, the recent rise of wide bandgap perovskite solar cells has inspired the development of new thin film tandem solar devices...
2018: Science and Technology of Advanced Materials
Jahan Zeb Gul, Memoon Sajid, Muhammad Muqeet Rehman, Ghayas Uddin Siddiqui, Imran Shah, Kyung-Hwan Kim, Jae-Wook Lee, Kyung Hyun Choi
Soft robots have received an increasing attention due to their advantages of high flexibility and safety for human operators but the fabrication is a challenge. Recently, 3D printing has been used as a key technology to fabricate soft robots because of high quality and printing multiple materials at the same time. Functional soft materials are particularly well suited for soft robotics due to a wide range of stimulants and sensitive demonstration of large deformations, high motion complexities and varied multi-functionalities...
2018: Science and Technology of Advanced Materials
Randy Jalem, Masanobu Nakayama, Yusuke Noda, Tam Le, Ichiro Takeuchi, Yoshitaka Tateyama, Hisatsugu Yamazaki
Increasing attention has been paid to materials informatics approaches that promise efficient and fast discovery and optimization of functional inorganic materials. Technical breakthrough is urgently requested to advance this field and efforts have been made in the development of materials descriptors to encode or represent characteristics of crystalline solids, such as chemical composition, crystal structure, electronic structure, etc. We propose a general representation scheme for crystalline solids that lifts restrictions on atom ordering, cell periodicity, and system cell size based on structural descriptors of directly binned Voronoi-tessellation real feature values and atomic/chemical descriptors based on the electronegativity of elements in the crystal...
2018: Science and Technology of Advanced Materials
Ana R Rebelo, Andrew J Archer, Xiuli Chen, Changqing Liu, Guang Yang, Yang Liu
Bacterial cellulose (BC) has interesting properties including high crystallinity, tensile strength, degree of polymerisation, water holding capacity (98%) and an overall attractive 3D nanofibrillar structure. The mechanical and electrochemical properties can be tailored upon incomplete BC dehydration. Under different water contents (100, 80 and 50%), the rheology and electrochemistry of BC were evaluated, showing a progressive stiffening and increasing resistance with lower capacitance after partial dehydration...
2018: Science and Technology of Advanced Materials
Aleksandar Staykov, Helena Tellez, John Druce, Ji Wu, Tatsumi Ishihara, John Kilner
Surface reactivity and near-surface electronic properties of SrO-terminated SrTiO3 and iron doped SrTiO3 were studied with first principle methods. We have investigated the density of states (DOS) of bulk SrTiO3 and compared it to DOS of iron-doped SrTiO3 with different oxidation states of iron corresponding to varying oxygen vacancy content within the bulk material. The obtained bulk DOS was compared to near-surface DOS, i.e. surface states, for both SrO-terminated surface of SrTiO3 and iron-doped SrTiO3 ...
2018: Science and Technology of Advanced Materials
Jinlong Du, Zaoming Wu, Engang Fu, Yanxiang Liang, Xingjun Wang, Peipei Wang, Kaiyuan Yu, Xiangdong Ding, Meimei Li, Marquis Kirk
The mechanism of radiation-induced detwinning is different from that of deformation detwinning as the former is dominated by supersaturated radiation-induced defects while the latter is usually triggered by global stress. In situ Kr ion irradiation was performed to study the detwinning mechanism of nanotwinned Cu films with various twin thicknesses. Two types of incoherent twin boundaries (ITBs), so-called fixed ITBs and free ITBs, are characterized based on their structural features, and the difference in their migration behavior is investigated...
2018: Science and Technology of Advanced Materials
Michael J Newman, Emily M Speller, Jérémy Barbé, Joel Luke, Meng Li, Zhe Li, Zhao-Kui Wang, Sagar M Jain, Ji-Seon Kim, Harrison Ka Hin Lee, Wing Chung Tsoi
Solution-processed organic small molecule solar cells (SMSCs) have achieved efficiency over 11%. However, very few studies have focused on their stability under illumination and the origin of the degradation during the so-called burn-in period. Here, we studied the burn-in period of a solution-processed SMSC using benzodithiophene terthiophene rhodamine:[6,6]-phenyl C71 butyric acid methyl ester (BTR:PC71 BM) with increasing solvent vapour annealing time applied to the active layer, controlling the crystallisation of the BTR phase...
2018: Science and Technology of Advanced Materials
Kaveh Edalati, Etsuo Akiba, Zenji Horita
High-pressure torsion (HPT) is widely used as a severe plastic deformation technique to create ultrafine-grained structures with promising mechanical and functional properties. Since 2007, the method has been employed to enhance the hydrogenation kinetics in different Mg-based hydrogen storage materials. Recent studies showed that the method is effective not only for increasing the hydrogenation kinetics but also for improving the hydrogenation activity, for enhancing the air resistivity and more importantly for synthesizing new nanostructured hydrogen storage materials with high densities of lattice defects...
2018: Science and Technology of Advanced Materials
Chaonan Chen, Zhewei Wang, Ke Wu, Hui Ye
Series of co-sputtered silver-indium tin oxide (Ag-ITO) films are systematically fabricated. By tuning the atomic ratio of silver, composite films are manifested to have different microstructures with limited silver amount (<3 at.%). Two stages for film morphology changing are proposed to describe different status and growth mechanisms. The introduction of silver improves the preferred orientations of In2 O3 component significantly. Remarkably, dielectric permittivity of Ag-ITO films is highly adjustable, allowing the cross-over wavelengths λ c to be changed by more than 300 nm through rapid post-annealing, and thus resulting in tunable epsilon-near-zero and plasmonic properties in the near-infrared region...
2018: Science and Technology of Advanced Materials
Sundar Kunwar, Puran Pandey, Mao Sui, Sushil Bastola, Jihoon Lee
Alloy nanoparticles (NPs) can offer a wide range of opportunities for various applications due to their composition and structure dependent properties such as multifunctionality, electronic heterogeneity, site-specific response, and multiple plasmon resonance bands. In this work, the fabrication of self-assembled Pdx Ag1-x NPs alloy nanostructures with distinct size, density, shape, and composition is demonstrated via the solid-state dewetting of sputtered Pd/Ag thin films on c-plane sapphire. The initial stage of bilayer dewetting exhibits the nucleation of voids, followed by the expansion of voids and cluster breakdown and finally shape transformation along with the temperature control...
2018: Science and Technology of Advanced Materials
Andrew J Clayton, Cecile M E Charbonneau, Wing C Tsoi, Peter J Siderfin, Stuart J C Irvine
Thin film tin sulphide (SnS) films were produced with grain sizes greater than 1 μm using a one-step metal organic chemical vapour deposition process. Tin-doped indium oxide (ITO) was used as the substrate, having a similar work function to molybdenum typically used as the back contact, but with potential use of its transparency for bifacial illumination. Tetraethyltin and ditertiarybutylsulphide were used as precursors with process temperatures 430-470 °C to promote film growth with large grains. The film stoichiometry was controlled by varying the precursor partial pressure ratios and characterised with energy dispersive X-ray spectroscopy to optimise the SnS composition...
2018: Science and Technology of Advanced Materials
Takashi Fukushima, Sho Kitano, Shinichi Hata, Miho Yamauchi
We demonstrated carbon-neutral (CN) energy circulation using glycolic acid ( GC )/oxalic acid ( OX ) redox couple. Here, we report fundamental studies on both catalyst search for power generation process, i.e. GC oxidation, and elemental steps for fuel generation process, i.e. OX reduction, in CN cycle. The catalytic activity test on various transition metals revealed that Rh, Pd, Ir, and Pt have preferable features as a catalyst for electrochemical oxidation of GC . A carbon-supported Pt catalyst in alkaline conditions exhibited higher activity, durability, and product selectivity for electrooxidation of GC rather than those in acidic media...
2018: Science and Technology of Advanced Materials
Nicola H Perry, Jae Jin Kim, Harry L Tuller
We compare approaches to measure oxygen surface exchange kinetics, by simultaneous optical transmission relaxation (OTR) and AC-impedance spectroscopy (AC-IS), on the same mixed conducting SrTi0.65 Fe0.35 O3-x film. Surface exchange coefficients were evaluated as a function of oxygen activity in the film, controlled by gas partial pressure and/or DC bias applied across the ionically conducting yttria-stabilized zirconia substrate. Changes in measured light transmission through the film over time (relaxations) resulted from optical absorption changes in the film corresponding to changes in its oxygen and oxidized Fe (~Fe4+ ) concentrations; such relaxation profiles were successfully described by the equation for surface exchange-limited kinetics appropriate for the film geometry...
2018: Science and Technology of Advanced Materials
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