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Pressure‐Dependent Polymorphism and Band‐Gap Tuning of Methylammonium Lead Iodide Perovskite

Angewandte Chemie 2016年第22期128卷

作者： Shaojie Jiang Yanan Fang Ruipeng Li Hai Xiao Jason Crowley Chenyu Wang Timothy J. White William A. Goddard Zhongwu Wang Tom Baikie Jiye Fang Materials Science and Engineering Program State University of New York at Binghamton Binghamton NY 13902 USA Energy Research Institute@NTU (ERI@N) Nanyang Technological University 50 Nanyang Drive Singapore 637553 Republic of Singapore Cornell High Energy Synchrotron Source Cornell University Ithaca NY 14853 USA Materials and Process Simulation Center (MSC) and Joint Center for Artificial Photosynthesis (JCAP) California Institute of Technology Pasadena CA 91125 USA Department of Chemistry State University of New York at Binghamton Binghamton NY 13902 USA School of Materials Science and Engineering Nanyang Technological University Nanyang Avenue Singapore 639798 Republic of Singapore

We report the pressure‐induced crystallographic transitions and optical behavior of MAPbI 3 (MA=methylammonium) using in situ synchrotron X‐ray diffraction and laser‐excited photoluminescence spectroscopy, supported by density functional theory (DFT) calculations using the hybrid functional B3PW91 with spin‐orbit coupling. The tetragonal polymorph determined at ambient pressure transforms to a ReO 3 ‐type cubic phase at 0.3 GPa. Upon continuous compression to 2.7 GPa this cubic polymorph converts into a putative orthorhombic structure. Beyond 4.7 GPa it separates into crystalline and amorphous fractions. During decompression, this phase‐mixed material undergoes distinct restoration pathways depending on the peak pressure. In situ pressure photoluminescence investigation suggests a reduction in band gap with increasing pressure up to ≈0.3 GPa and then an increase in band gap up to a pressure of 2.7 GPa, in excellent agreement with our DFT calculation prediction.

关键词： Bandlücken Halogenid-Perowskite Hochdruckchemie Phasenübergänge Photolumineszenz

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Biopolymer-based gel casting of ferroelectric ceramics

Biopolymer-based gel casting of ferroelectric ceramics

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作者： Plucknett, Kevin P. Munro, Cameron D. Materials Engineering Program Department of Process Engineering and Applied Science 1360 Barrington Street Halifax NS B3H 4X2 Canada Halifax NS B3H 4X2 Canada

Ferroelectric ceramics have a wide range of industrial applications. While components can be formed through simple 'press and sinter' approaches, there is an increasing need for more flexible processing methods. Suspension based forming promotes greater homogeneity, through elimination of processing defects, and allows the formation of more complex shaped components. In the present work, the application of aqueous gel casting technologies is reviewed, and in particular the use of natural biopolymers as gelation aids for such approaches. Recent studies of the application of such technology to complex shape forming of BaTiO3 ferroelectric ceramics are examined. Emphasis is placed upon a simple subtractive rapid prototyping method, utilizing aqueous gel casting in combination with green machining. Aqueous gel casting of ferroelectric ceramics is investigated, using agar as a gelling aid. Combining high-solids content BaTiO3 suspensions (55vol%), with concentrated agar solutions (up to 8wt%), allows casting of components with high green densities (and final agar concentrations up to 1wt% of the solids loading), which can be subsequently green-machined. Fine scale features (≈300μm thick), with high aspect ratios (up to 13:1), are successfully fabricated. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

关键词： Aspect ratio

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Corrigendum to “Elevated temperature nanoindentation characterization of poly( para -phenylene vinylene) conjugated polymer films” [Polym. Test. 41 (2015) 17–25]

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Polymer Testing 2015年 42卷 234-234页

作者： Nimitt G. Patel Arvind Sreeram Ramaswamy I. Venkatanarayanan Sitaraman Krishnan Philip A. Yuya Department of Mechanical and Aeronautical Engineering Clarkson University Potsdam NY 13699 USA Materials Science and Engineering PhD Program Clarkson University Potsdam NY 13699 USA Department of Chemical and Biomolecular Engineering Clarkson University Potsdam NY 13699 USA

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Temperature-dependent isotropic-to-nematic transition of charged nanoplates

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Physical Review E 2014年第2期90卷 020504(R)-020504(R)页

作者： Huawei Li Xuezhen Wang Ying Chen Zhengdong Cheng Soft Matter Center Guangdong Provincial Key Laboratory on Functional Soft Condensed Matter School of Materials and Energy Guangdong University of Technology Guangzhou 510006 China Artie McFerrin Department of Chemical Engineering Texas A&M University College Station Texas 77843-3122 USA Mary Kay O’Connor Process Safety Center Artie McFerrin Department of Chemical Engineering Texas A&M University College Station Texas 77843-3122 USA Department of Materials Science and Engineering Texas A&M University College Station Texas 77843-3003 USA Professional Program in Biotechnology Texas A&M University College Station Texas 77843-3122 USA

Studies of temperature-dependent phase behaviors of discotic colloids are found infrequently in the literature. We establish here the isotropic-to-nematic (I-N) transition phase diagram of charged platelets in the temperature-versus-volume fraction plane. We discover that the N phase can be melted by increasing temperature, and that coexistent samples are more sensitive to polydispersity at higher temperature and higher concentration.

关键词： ISOTROPIC properties PHASE transformations (Physics) DISCOTIC liquid crystals PHASE diagrams POLYDISPERSE media

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Pilot study of hydrogen-rich syngas production from ma bamboo (Dendrocalamus latiforus) by plasma reforming

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Taiwan Journal of Forest science 2014年第4期29卷 239-249页

作者： Juan, Sun-Wen Wang, Chi-Sheng Huang, Jin-Cherng Wang, Ya-Nan Ting, Ching-Hua Shiah, Tsang-Chyi Liu, Su-Ling PhD Program of Agriculture Science National Chiayi Univ. 300 Syuefu Rd. Chiayi City60004 Taiwan Advanced Propulsion and Power System Research Center National Cheng Kung Univ. 2500 Jhongjheng S. Rd. Sec. 1 Gueiren Dist. Tainan71150 Taiwan Department of Wood Based Materials and Design National Chiayi Univ. 300 Syuefu Rd. Chiayi City60004 Taiwan School of Forestry and Resource Conservation National Taiwan Univ. 1 Roosevelt Rd. Sec. 4 Taipei10617 Taiwan Department of Mechanical and Energy Engineering National Chiayi Univ. 300 Syuefu Rd. Chiayi City60004 Taiwan Experimental Forest College of Bio-Resources and Agriculture National Taiwan Univ. 12 Chienshan Rd. Sec. 1 Chushan Township Nantou County55750 Taiwan

Major components of bamboo are solid hydrocarbons in the forms of cellulose, hemicellulose, lignins, and pentosan. The abundance of hydrocarbons indicates the potential of bamboo to be an excellent raw material to produce hydrogen. In this study, 1-yr-old ma bamboo (Dendrocalamus latiforus) was liquefed with polyethylene glycol and then treated with plasma steam reforming to produce hydrogen. Productivity levels of hydrogen at different bamboo concentrations and pyrolysis temperatures were experimentally and theoretically studied. The liquefaction and pyrolysis apparatuses were hence optimized. A maximum productivity occurred at a weight ratio of 1:10 of ma bamboo to water and a pyrolysis temperature of 800°C by plasma treatment.

关键词： Hydrogen production

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Electroless nickel phosphorus plating on carbon steel

Electroless nickel phosphorus plating on carbon steel

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materials science and Technology Conference and Exhibition 2013, MS and T 2013

作者： Lin, Cui Dadvand, Nazila Farhat, Zoheir Kipouros, Georges J. Materials Engineering Program Department of Process Engineering and Applied Science Dalhousie University 1360 Barrington Street Halifax NS B3H 4R2 Canada School of Material Science and Engineering Nanchang Hangkong University 696 Fenghenan Road Nanchang Jiangxi 330063 China

ISBN: (纸本)9781629933092

Electroless nickel-phosphorus coatings are important for corrosion and wear protection. The preparation of electroless nickel-phosphorus coating on carbon steel substrate in an ammonia free friendly bath consisting of Nichem 1125-2A 75g/L and Nichem 1125-2B 230g/L at a temperature of 89°C and pH of 4.8 for 90 minutes was studied. Optical microscopy(OM), field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), x-ray diffraction (XRD) were utilized to characterize the deposits. A nanoindentation system and a dry reciprocating wear test were used to investigate microhardness and wear resistance, respectively. A homogeneous coating with good adherence was produced. Structural characterization suggests that the deposited Ni-P coating has an amorphous structure with 9-11 wt.% phosphorus content. The micro-hardness of Ni-P coating is more than twofold that of substrate, indicating the coating can improve the hardness of carbon steel. The wear rates and steady state friction coefficients of Ni-P coating and carbon steel are 4.77×10 -2 mg/m, 0.37 and 5.63×10-2 mg/m, 0.51, respectively, at a load of 6N under dry sliding condition, This reveals that the Ni-P coating can offer better wear resistance compared to carbon steel. Copyright © 2013 MS&T'13®.

关键词： Wear resistance

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Characteristics of Leachate at Sukawinatan Landfill, Palembang, Indonesia

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Journal of Physics: Conference Series 2013年第1期423卷

作者： Eka Sri Yusmartini Dedi Setiabudidaya Ridwan Marsi Faizal PhD Candidate Postgraduate Program Sriwijaya University Indonesia Department of Physics Faculty of Mathematics and Science Sriwijaya University Indonesia Nuclear Industrial Materials Technology Centre Serpong Indonesia Faculty of Agriculture Sriwijaya University Indonesia Department of Chemical Engineering Faculty of Engineering Sriwijaya University Indonesia

Landfill (TPA) Sukawinatan Palembang is an open dumping system which covers an area of 25 hectares. This system may bring an environmental damage to the surrounding area because it does not provide leachate treatment. Leachate is the landfill waste that dissolves many compounds that contain pollutants from both organic substances and heavy metal origin. This paper presents the results of laboratory analysis on samples of leachate as well as shallow groundwater from the surrounding area. The results were compared to established quality standards to evaluate whether the leachate has influenced the quality of the shallow groundwater in the surrounding area. The results show that there are some indications that the quality of groundwater has been polluted by the leachate of both organic substances and heavy metals produced by the Sukawinatan landfill.

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Aspect ratio and polydispersity dependence of isotropic-nematic transition in discotic suspensions

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Physical Review E 2012年第6期85卷 061708-061708页

作者： Andres F. Mejia Ya-Wen Chang Ratna Ng Min Shuai M. Sam Mannan Zhengdong Cheng Artie McFerrin Department of Chemical Engineering Texas A&M University College Station Texas 77843-3122 USA Artie McFerrin Department of Chemical Engineering Mary Kay O’Connor Process Safety Center Texas A&M University College Station Texas 77843-3122 USA Materials Science and Engineering Program Texas A&M University College Station Texas 77843-3003 USA Professional Program in Biotechnology Texas A&M University College Station Texas 77843-3122 USA

We demonstrate the strong dependency of the isotropic-nematic (I-N) transition of discotic suspensions on the aspect ratio (ξ = thickness/diameter) via control of the sizes of pristine ZrP crystals and subsequent exfoliation to monolayers. The size fractionation of the I-N transition facilitates the analysis of the effect of polydispersity. A systematic variation in the aspect ratio in the low aspect ratio region (0.001 < ξ < 0.01) showed that the I-N transition volume fraction increases with the aspect ratio in agreement with computer simulations. It was found that the transition volume fractions scale with aspect ratio φI,N = mξ1.36±0.07, where the prefactor m strongly depends on size polydispersity for φN but does not depend on size polydispersity for φI with φI and φN being the volume fractions of the isotropic and the nematic phases on the cloud curves, respectively.

关键词： NEMATIC liquid crystals PHASE transformations (Physics) SUSPENSIONS (Chemistry) THICKNESS measurement SEPARATION (Technology) MONOMOLECULAR films SIMULATION methods & models

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Validation of predicted residual stresses within direct chill cast magnesium alloy slab

Validation of predicted residual stresses within direct chil...

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作者： Turski, Mark Paradowska, Anna Zhang, Shu-Yan Mortensen, Dag Fjaer, Hallvard Grandfield, John Davis, Bruce Delorme, Rick Materials Engineering Open University Milton Keynes MK7 6AA United Kingdom Menei NSW 2234 Australia ISIS Facility Science and Technology Facilities Council Rutherford Appleton Laboratory Didcot Oxfordshire OX11 0QX United Kingdom ISIS Facility Science and Technology Facilities Council Rutherford Appleton Laboratory United States Department of Process and Fluid Flow Technology Institute for Energy Technology N-2027 Kjeller Norway Grandfield Technology Pty Ltd PO BOX 5110 Moreland West VIC 3055 Australia Swinburne University of Technology Faculty of Engineering and Industrial Science Hawthorn VIC 3122 Australia Research and Development Program Madison IL 62060 United States Magnesium Elektron North America Madison IL 62060 United States

A significant level of cold cracking has been observed within direct chill (DC) cast, high-strength magnesium alloy Elektron WE43. These cracks have been attributed to the formation of significant residual stresses during casting. A finite-element modeling (FEM) code, which is called ALSIM, has been used to predict the residual stress within the DC-cast slab. Verification of the predicted residual stress field within an 870 9 315-mm sized slab has been carried out using neutron diffraction measurements. Given that measurements in such large-scale components using diffraction measurements are particularly challenging and expensive, the efficient use of neutron diffraction measurements is emphasized. This has included the use of sectioning, allowing the residual stress within the slab to be mapped in detail. © 2012 The Minerals, Metals & materials Society and ASM International.

关键词： Residual stresses

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Q&A

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Design Management Review 2014年第3期25卷

作者： John Maeda Steven Heller Tim Hoover Has been a design partner at Kleiner Perkins Caufield & Byers since January 2014 helping entrepreneurs and portfolio companies to build design into their company cultures. He served as the president of Rhode Island School of Design for six years through 2013 and also served as an associate director of research at the MIT Media Lab. Maeda has been a practicing designer since 1990 and his work is in the permanent collections of the Museum of Modern Art San Francisco Museum of Modern Art and the Cartier Foundation. He serves on the boards of several corporations including Sonos and Wieden + Kennedy and is chair of eBay's Design Advisory Board. His four published books include The Laws of Simplicity and Redesigning Leadership. Maeda is the recipient of a variety of international awards for his creative work including induction into the Art Director's Club Hall of Fame. In 2001 he received the White House National Design Award in 2002 he received the Mainichi Design Prize in Japan and in 2005 he was awarded the Raymond Loewy Foundation Prize in Germany. Maeda earned a BS and an MS from MIT in computer science and electrical engineering. He received a PhD in design science from the University of Tsukuba Institute of Art and Design in Japan as well as an MBA from Arizona State University. Co‐chair and co‐founder of the MFA Designer as Author and Entrepreneur program at the School of Visual Arts in New York. He was the art director of The New York Times Book Review and now writes the VISUALS column for the NYTBR. He also writes “The Daily Heller” at *** a weekly online design column for Atlantic magazine. He is author co‐author and editor of more than 165 books on the history and practice of graphic design illustration and satiric art. His forthcoming books include 100 Classic Graphic Design Magazines (Laurence King Publishers) and Raw Data: The Process Behind Information Graphics (Thames + Hudson). Heller was the 2011 recipient of the Smithsonian National Design Award for Design Mind. He has also writ

John Maeda is a past president of Rhode Island School of Design and an internationally known designer. He's now involved in helping entrepreneurs build design into their company cultures. Writer and educator Steven Heller pairs up with Tim Hoover, head of product and design at Canary, to talk about designer CEOs, start‐ups, and cutting out the middleman.

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