Ultrahigh thermal conductivity confirmed in boron arsenide
Source: ScienceNOW - August 9, 2018 Category: Science Authors: Dames, C. Tags: Physics, Applied, Materials Science perspective Source Type: news
Experimental observation of high thermal conductivity in boron arsenide
Improving the thermal management of small-scale devices requires developing materials with high thermal conductivities. The semiconductor boron arsenide (BAs) is an attractive target because of ab initio calculation indicating that single crystals have an ultrahigh thermal conductivity. We synthesized BAs single crystals without detectable defects and measured a room-temperature thermal conductivity of 1300 watts per meter-kelvin. Our spectroscopy study, in conjunction with atomistic theory, reveals that the distinctive band structure of BAs allows for very long phonon mean free paths and strong high-order anharmonicity th...
Source: ScienceNOW - August 9, 2018 Category: Science Authors: Kang, J. S., Li, M., Wu, H., Nguyen, H., Hu, Y. Tags: Physics, Applied, Materials Science reports Source Type: news
High thermal conductivity in cubic boron arsenide crystals
We report the experimental discovery of high thermal conductivity at room temperature in cubic boron arsenide (BAs) grown through a modified chemical vapor transport technique. The thermal conductivity of BAs, 1000 ± 90 watts per meter per kelvin meter-kelvin, is higher than that of silicon carbide by a factor of 3 and is surpassed only by diamond and the basal-plane value of graphite. This work shows that BAs represents a class of ultrahigh–thermal conductivity materials predicted by a recent theory, and that it may constitute a useful thermal management material for high–power density electronic device...
Source: ScienceNOW - August 9, 2018 Category: Science Authors: Li, S., Zheng, Q., Lv, Y., Liu, X., Wang, X., Huang, P. Y., Cahill, D. G., Lv, B. Tags: Physics, Applied, Materials Science reports Source Type: news
Giant polarization in super-tetragonal thin films through interphase strain
Strain engineering has emerged as a powerful tool to enhance the performance of known functional materials. Here we demonstrate a general and practical method to obtain super-tetragonality and giant polarization using interphase strain. We use this method to create an out-of-plane–to–in-plane lattice parameter ratio of 1.238 in epitaxial composite thin films of tetragonal lead titanate (PbTiO3), compared to 1.065 in bulk. These thin films with super-tetragonal structure possess a giant remanent polarization, 236.3 microcoulombs per square centimeter, which is almost twice the value of known ferroelectrics. The ...
Source: ScienceNOW - August 2, 2018 Category: Science Authors: Zhang, L., Chen, J., Fan, L., Dieguez, O., Cao, J., Pan, Z., Wang, Y., Wang, J., Kim, M., Deng, S., Wang, J., Wang, H., Deng, J., Yu, R., Scott, J. F., Xing, X. Tags: Materials Science, Physics reports Source Type: news
3D Printer of PEKK Implants Expanding in Asia
After receiving accreditation as a foreign medical device manufacturer by the Japanese Ministry of Health, Labour, and Welfare, Oxford Performance Materials Inc. (OPM) has forged a partnership to establish manufacturing and marketing in Japan. Known for its 3D printed PEKK OsteoFab implants, its contract manufacturing services, and its OXPEKK materials technology, OPM has partnered with Tokyo-based materials supplier JSR Corp. (JSR) to form OPM Asia. The OPM Asia license includes Japan, China, Taiwan, Korea, Brunei Darussalam, Cambodia, Lao PDR, Malaysia, Myanmar, Philippines, Singapore, Thailand, Vietnam, and India. Manuf...
Source: MDDI - July 20, 2018 Category: Medical Devices Authors: Daphne Allen Tags: 3-D Printing Source Type: news
Wallpaper fermions and the nonsymmorphic Dirac insulator
Materials whose gapless surface states are protected by crystal symmetries include mirror topological crystalline insulators and nonsymmorphic hourglass insulators. There exists only a very limited set of possible surface crystal symmetries, captured by the 17 "wallpaper groups." Here we show that a consideration of symmetry-allowed band degeneracies in the wallpaper groups can be used to understand previously described topological crystalline insulators and to predict phenomenologically distinct examples. In particular, the two wallpaper groups with multiple glide lines, pgg and p4g, allow for a topological insu...
Source: ScienceNOW - July 19, 2018 Category: Science Authors: Wieder, B. J., Bradlyn, B., Wang, Z., Cano, J., Kim, Y., Kim, H.-S. D., Rappe, A. M., Kane, C. L., Bernevig, B. A. Tags: Materials Science, Physics r-articles Source Type: news
Torsional instability in the single-chain limit of a transition metal trichalcogenide
We report the synthesis of the quasi–one-dimensional transition metal trichalcogenide NbSe3 (niobium triselenide) in the few-chain limit, including the realization of isolated single chains. The chains are encapsulated in protective boron nitride or carbon nanotube sheaths to prevent oxidation and to facilitate characterization. Transmission electron microscopy reveals static and dynamic structural torsional waves not found in bulk NbSe3 crystals. Electronic structure calculations indicate that charge transfer drives the torsional wave instability. Very little covalent bonding is found between the chains and the nano...
Source: ScienceNOW - July 19, 2018 Category: Science Authors: Pham, T., Oh, S., Stetz, P., Onishi, S., Kisielowski, C., Cohen, M. L., Zettl, A. Tags: Materials Science, Physics reports Source Type: news
New Report Identifies Five Breakthroughs to Address Urgent Challenges and Advance Food and Agricultural Sciences by 2030
A new report from the National Academies of Sciences, Engineering, and Medicine identifies the most promising scientific breakthroughs that are possible to achieve in the next decade to increase the U.S. food and agriculture system's sustainability, competitiveness, and resilience. The urgent progress needed today, given challenges such as water scarcity, increased weather variability, floods, and droughts, requires a convergent research approach that harnesses advances in data science, materials science, information technology, behavioral sciences, economics, and many other fields. Read More (Source: News from the National Academies)
Source: News from the National Academies - July 18, 2018 Category: Science Source Type: news
Controlling the manufacture of stable aerogels
(Kyoto University) Kyoto University researchers have developed a new approach to control the fabrication of soft, porous materials, overcoming a primary challenge in materials science. (Source: EurekAlert! - Biology)
Source: EurekAlert! - Biology - July 12, 2018 Category: Biology Source Type: news
Metal-free three-dimensional perovskite ferroelectrics
Inorganic perovskite ferroelectrics are widely used in nonvolatile memory elements, capacitors, and sensors because of their excellent ferroelectric and other properties. Organic ferroelectrics are desirable for their mechanical flexibility, low weight, environmentally friendly processing, and low processing temperatures. Although almost a century has passed since the first ferroelectric, Rochelle salt, was discovered, examples of highly desirable organic perovskite ferroelectrics are lacking. We found a family of metal-free organic perovskite ferroelectrics with the characteristic three-dimensional structure, among which ...
Source: ScienceNOW - July 12, 2018 Category: Science Authors: Ye, H.-Y., Tang, Y.-Y., Li, P.-F., Liao, W.-Q., Gao, J.-X., Hua, X.-N., Cai, H., Shi, P.-P., You, Y.-M., Xiong, R.-G. Tags: Chemistry, Materials Science r-articles Source Type: news
The NHS needs a new breed of innovator for the information age | Kevin Fong
Technology is never going to replace doctors - or make healthcare cheaper. But data and artificial intelligence are the futureFrom vaccines and antibiotics tomemory metal stents that widen narrowed arteries and algorithms that process radiological images and let us see the earliest signs of disease,innovation has been saving lives since the inception of theNational Health Service 70 years ago. It is this blend of new molecules, materials science and biomedical engineering, in partnership with digital systems, that will continue to transform our expectations of life and survival in the 21st century.While the digital revolut...
Source: Guardian Unlimited Science - July 6, 2018 Category: Science Authors: Kevin Fong Tags: NHS Technology Health Medical research Science Society UK news Source Type: news
Single-crystal x-ray diffraction structures of covalent organic frameworks
The crystallization problem is an outstanding challenge in the chemistry of porous covalent organic frameworks (COFs). Their structural characterization has been limited to modeling and solutions based on powder x-ray or electron diffraction data. Single crystals of COFs amenable to x-ray diffraction characterization have not been reported. Here, we developed a general procedure to grow large single crystals of three-dimensional imine-based COFs (COF-300, hydrated form of COF-300, COF-303, LZU-79, and LZU-111). The high quality of the crystals allowed collection of single-crystal x-ray diffraction data of up to 0.83-angstr...
Source: ScienceNOW - July 5, 2018 Category: Science Authors: Ma, T., Kapustin, E. A., Yin, S. X., Liang, L., Zhou, Z., Niu, J., Li, L.-H., Wang, Y., Su, J., Li, J., Wang, X., Wang, W. D., Wang, W., Sun, J., Yaghi, O. M. Tags: Chemistry, Materials Science reports Source Type: news
Seeded growth of single-crystal two-dimensional covalent organic frameworks
Polymerization of monomers into periodic two-dimensional networks provides structurally precise, layered macromolecular sheets that exhibit desirable mechanical, optoelectronic, and molecular transport properties. Two-dimensional covalent organic frameworks (2D COFs) offer broad monomer scope but are generally isolated as powders comprising aggregated nanometer-scale crystallites. We found that 2D COF formation could be controlled using a two-step procedure in which monomers are added slowly to preformed nanoparticle seeds. The resulting 2D COFs are isolated as single-crystalline, micrometer-sized particles. Transient abso...
Source: ScienceNOW - July 5, 2018 Category: Science Authors: Evans, A. M., Parent, L. R., Flanders, N. C., Bisbey, R. P., Vitaku, E., Kirschner, M. S., Schaller, R. D., Chen, L. X., Gianneschi, N. C., Dichtel, W. R. Tags: Chemistry, Materials Science reports Source Type: news
Observation of an environmentally insensitive solid-state spin defect in diamond
We report a color center that shows insensitivity to environmental decoherence caused by phonons and electric field noise: the neutral charge state of silicon vacancy (SiV0). Through careful materials engineering, we achieved>80% conversion of implanted silicon to SiV0. SiV0 exhibits spin-lattice relaxation times approaching 1 minute and coherence times approaching 1 second. Its optical properties are very favorable, with ~90% of its emission into the zero-phonon line and near–transform-limited optical linewidths. These combined properties make SiV0 a promising defect for quantum network applications. (Source: ScienceNOW)
Source: ScienceNOW - July 5, 2018 Category: Science Authors: Rose, B. C., Huang, D., Zhang, Z.-H., Stevenson, P., Tyryshkin, A. M., Sangtawesin, S., Srinivasan, S., Loudin, L., Markham, M. L., Edmonds, A. M., Twitchen, D. J., Lyon, S. A., de Leon, N. P. Tags: Materials Science, Physics reports Source Type: news
See-through solar cells could power offices
Source: ScienceNOW - June 28, 2018 Category: Science Authors: Service, R. F. Tags: Engineering, Materials Science In Depth Source Type: news
Multivalent counterions diminish the lubricity of polyelectrolyte brushes
Polyelectrolyte brushes provide wear protection and lubrication in many technical, medical, physiological, and biological applications. Wear resistance and low friction are attributed to counterion osmotic pressure and the hydration layer surrounding the charged polymer segments. However, the presence of multivalent counterions in solution can strongly affect the interchain interactions and structural properties of brush layers. We evaluated the lubrication properties of polystyrene sulfonate brush layers sliding against each other in aqueous solutions containing increasing concentrations of counterions. The presence of mu...
Source: ScienceNOW - June 28, 2018 Category: Science Authors: Yu, J., Jackson, N. E., Xu, X., Morgenstern, Y., Kaufman, Y., Ruths, M., de Pablo, J. J., Tirrell, M. Tags: Chemistry, Materials Science reports Source Type: news
Enhanced photovoltage for inverted planar heterojunction perovskite solar cells
The highest power conversion efficiencies (PCEs) reported for perovskite solar cells (PSCs) with inverted planar structures are still inferior to those of PSCs with regular structures, mainly because of lower open-circuit voltages (Voc). Here we report a strategy to reduce nonradiative recombination for the inverted devices, based on a simple solution-processed secondary growth technique. This approach produces a wider bandgap top layer and a more n-type perovskite film, which mitigates nonradiative recombination, leading to an increase in Voc by up to 100 millivolts. We achieved a high Voc of 1.21 volts without sacrificin...
Source: ScienceNOW - June 28, 2018 Category: Science Authors: Luo, D., Yang, W., Wang, Z., Sadhanala, A., Hu, Q., Su, R., Shivanna, R., Trindade, G. F., Watts, J. F., Xu, Z., Liu, T., Chen, K., Ye, F., Wu, P., Zhao, L., Wu, J., Tu, Y., Zhang, Y., Yang, X., Zhang, W., Friend, R. H., Gong, Q., Snaith, H. J., Zhu, R. Tags: Materials Science, Physics reports Source Type: news
Two-channel model for ultralow thermal conductivity of crystalline Tl3VSe4
Solids with ultralow thermal conductivity are of great interest as thermal barrier coatings for insulation or thermoelectrics for energy conversion. However, the theoretical limits of lattice thermal conductivity () are unclear. In typical crystals a phonon picture is valid, whereas lowest values occur in highly disordered materials where this picture fails and heat is supposedly carried by random walk among uncorrelated oscillators. Here we identify a simple crystal, Tl3VSe4, with a calculated phonon [0.16 Watts per meter-Kelvin (W/m-K)] one-half that of our measured (0.30 W/m-K) at 300 K, approaching disorder values, alt...
Source: ScienceNOW - June 28, 2018 Category: Science Authors: Mukhopadhyay, S., Parker, D. S., Sales, B. C., Puretzky, A. A., McGuire, M. A., Lindsay, L. Tags: Materials Science, Physics reports Source Type: news
Scientists develop thermal camouflage that can fool infrared cameras
Invention can make an object appear to have the same temperature as its backgroundScientists have developed a thin, lightweight and flexible film that can outfox infrared cameras, allowing hot bodies to appear cool and cold items to appear warm. The invention can also help camouflage an object by making it appear the same temperature as its background.The design was inspired by the colour-shifting capabilities of cuttlefish, says Coskun Kocabas, a co-author of the research from the University of Manchester.Continue reading... (Source: Guardian Unlimited Science)
Source: Guardian Unlimited Science - June 27, 2018 Category: Science Authors: Nicola Davis Tags: Materials science Physics Chemistry Source Type: news
An unlikely marriage among oxides
(Swiss Federal Laboratories for Materials Science and Technology (EMPA)) Sebastian Siol is looking for new materials with unusual properties that were so far not accessible in experiments. To do this, he connects partners who don't really fit together: One partner forces the other into a state that would not be possible without the unlikely pairing. Siol also makes sure that the crystal bonds last in everyday life. Only then are they interesting for industrial applications. (Source: EurekAlert! - Biology)
Source: EurekAlert! - Biology - June 19, 2018 Category: Biology Source Type: news
UNF, Mayo experiment with rare 3-D microscope
Researchers at the University of North Florida's Materials Science and Engineering Research Facility watched as dozens of dots scattered across their computer screen. Some dots balled up, others exploded. The dots were cancerous cells from a brain tumor recently removed by a Mayo Clinic neurosurgeon. The visual was made possible by an advanced microscope, the only one of its kind in North America, which can zoom into individual cells without staining and killing cells, as microscopes typically do. "It… (Source: bizjournals.com Health Care:Physician Practices headlines)
Source: bizjournals.com Health Care:Physician Practices headlines - June 18, 2018 Category: American Health Authors: Will Robinson Source Type: news
Giant tunneling magnetoresistance in spin-filter van der Waals heterostructures
Magnetic multilayer devices that exploit magnetoresistance are the backbone of magnetic sensing and data storage technologies. Here, we report multiple-spin-filter magnetic tunnel junctions (sf-MTJs) based on van der Waals (vdW) heterostructures in which atomically thin chromium triiodide (CrI3) acts as a spin-filter tunnel barrier sandwiched between graphene contacts. We demonstrate tunneling magnetoresistance that is drastically enhanced with increasing CrI3 layer thickness, reaching a record 19,000% for magnetic multilayer structures using four-layer sf-MTJs at low temperatures. Using magnetic circular dichroism measure...
Source: ScienceNOW - June 14, 2018 Category: Science Authors: Song, T., Cai, X., Tu, M. W.-Y., Zhang, X., Huang, B., Wilson, N. P., Seyler, K. L., Zhu, L., Taniguchi, T., Watanabe, K., McGuire, M. A., Cobden, D. H., Xiao, D., Yao, W., Xu, X. Tags: Materials Science reports Source Type: news
Keep Your Medtech Game On Point at MD & amp;M East
It is time once again for medical device engineers, R&D managers, product design professionals, and medtech executives to convene at the Javits Center in New York for Medical Design & Manufacturing (MD&M) East, June 12-14. This guide is just a sample of how this must-attend industry event will help you keep your medtech game on point. Not registered? No problem, you can register right here. Meet a Medtech Rock Star The opportunity to meet an industry pioneer isn't one to take for granted. This year, during the 20th annual Medical Design Excellence Awards (MDEA) ceremony, Robert Jarvik will be a...
Source: MDDI - June 7, 2018 Category: Medical Devices Authors: Amanda Pedersen Tags: MD & M East (New York) Business Source Type: news
Neuromorphic circuits impart a sense of touch
Source: ScienceNOW - May 31, 2018 Category: Science Authors: Bartolozzi, C. Tags: Engineering, Materials Science perspective Source Type: news
A bioinspired flexible organic artificial afferent nerve
The distributed network of receptors, neurons, and synapses in the somatosensory system efficiently processes complex tactile information. We used flexible organic electronics to mimic the functions of a sensory nerve. Our artificial afferent nerve collects pressure information (1 to 80 kilopascals) from clusters of pressure sensors, converts the pressure information into action potentials (0 to 100 hertz) by using ring oscillators, and integrates the action potentials from multiple ring oscillators with a synaptic transistor. Biomimetic hierarchical structures can detect movement of an object, combine simultaneous pressur...
Source: ScienceNOW - May 31, 2018 Category: Science Authors: Kim, Y., Chortos, A., Xu, W., Liu, Y., Oh, J. Y., Son, D., Kang, J., Foudeh, A. M., Zhu, C., Lee, Y., Niu, S., Liu, J., Pfattner, R., Bao, Z., Lee, T.-W. Tags: Engineering, Materials Science reports Source Type: news
Imaging of pure spin-valley diffusion current in WS2-WSe2 heterostructures
In this study we demonstrate efficient generation of a pure and locked spin-valley diffusion current in tungsten disulfide (WS2)–tungsten diselenide (WSe2) heterostructures without any driving electric field. We imaged the propagation of valley current in real time and space by pump-probe spectroscopy. The valley current in the heterostructures can live for more than 20 microseconds and propagate over 20 micrometers; both the lifetime and the diffusion length can be controlled through electrostatic gating. The high-efficiency and electric-field–free generation of a locked spin-valley current in TMDC heterostruc...
Source: ScienceNOW - May 24, 2018 Category: Science Authors: Jin, C., Kim, J., Utama, M. I. B., Regan, E. C., Kleemann, H., Cai, H., Shen, Y., Shinner, M. J., Sengupta, A., Watanabe, K., Taniguchi, T., Tongay, S., Zettl, A., Wang, F. Tags: Materials Science, Physics reports Source Type: news
Long-range exciton transport in conjugated polymer nanofibers prepared by seeded growth
We describe the preparation of organic semiconducting nanofibers comprising a crystalline poly(di-n-hexylfluorene) core and a solvated, segmented corona consisting of polyethylene glycol in the center and polythiophene at the ends. These nanofibers exhibit exciton transfer from the core to the lower-energy polythiophene coronas in the end blocks, which occurs in the direction of the interchain - stacking with very long diffusion lengths (>200 nanometers) and a large diffusion coefficient (0.5 square centimeters per second). This is made possible by the uniform exciton energetic landscape created by the well-ordered, cry...
Source: ScienceNOW - May 24, 2018 Category: Science Authors: Jin, X.-H., Price, M. B., Finnegan, J. R., Boott, C. E., Richter, J. M., Rao, A., Menke, S. M., Friend, R. H., Whittell, G. R., Manners, I. Tags: Materials Science reports Source Type: news
UTIA research continues to advance biofuels, bioenergy and biobased products
(University of Tennessee Institute of Agriculture) David Harper, an associate professor of materials science in the UT Center for Renewable Carbon, will lead a $1.4M award from the US Department of Energy through the Biomass Research and Development Initiative (BRDI) -- a joint program organized through DOE and the US Department of Agriculture. The goal of BRDI is to develop economically and environmentally sustainable sources of biomass and increase the availability of competitively priced renewable fuels and biobased products. (Source: EurekAlert! - Biology)
Source: EurekAlert! - Biology - May 22, 2018 Category: Biology Source Type: news
Sir Roger Elliott obituary
Specialist in theoretical physics who investigated the structure of matterOn Roger Elliott ’s 60th birthday, a conference in his honour displayed beneath his photograph the title: “Disorder in Condensed Matter Physics”. This reference to his speciality in theoretical physics, where he made important contributions to theories of optical, magnetic and semiconductor properties of the s olid state, was ironic, for Elliott, who has died aged 89, was a man of the soundest judgment.His opinion was widely sought and highly regarded, as professor at Oxford University (1974-96), as chief executive of Oxford Univers...
Source: Guardian Unlimited Science - May 18, 2018 Category: Science Authors: Frank Close Tags: Physics Materials science Education University of Oxford Higher education Source Type: news
Hybrid molecular-colloidal liquid crystals
Order and fluidity often coexist, with examples ranging from biological membranes to liquid crystals, but the symmetry of these soft-matter systems is typically higher than that of the constituent building blocks. We dispersed micrometer-long inorganic colloidal rods in a nematic liquid crystalline fluid of molecular rods. Both types of uniaxial building blocks, while freely diffusing, interact to form an orthorhombic nematic fluid, in which like-sized rods are roughly parallel to each other and the molecular ordering direction is orthogonal to that of colloidal rods. A coarse-grained model explains the experimental temper...
Source: ScienceNOW - May 17, 2018 Category: Science Authors: Mundoor, H., Park, S., Senyuk, B., Wensink, H. H., Smalyukh, I. I. Tags: Materials Science, Physics reports Source Type: news
Extraordinary plasticity of an inorganic semiconductor in darkness
Inorganic semiconductors generally tend to fail in a brittle manner. Here, we report that extraordinary "plasticity" can take place in an inorganic semiconductor if the deformation is carried out "in complete darkness." Room-temperature deformation tests of zinc sulfide (ZnS) were performed under varying light conditions. ZnS crystals immediately fractured when they deformed under light irradiation. In contrast, it was found that ZnS crystals can be plastically deformed up to a deformation strain of t = 45% in complete darkness. In addition, the optical bandgap of the deformed ZnS crystals was distinctl...
Source: ScienceNOW - May 17, 2018 Category: Science Authors: Oshima, Y., Nakamura, A., Matsunaga, K. Tags: Materials Science reports Source Type: news
3D charge and 2D phonon transports leading to high out-of-plane ZT in n-type SnSe crystals
Thermoelectric technology enables the harvest of waste heat and its direct conversion into electricity. The conversion efficiency is determined by the materials figure of merit ZT. Here we show a maximum ZT of ~2.8 ± 0.5 at 773 kelvin in n-type tin selenide (SnSe) crystals out of plane. The thermal conductivity in layered SnSe crystals is the lowest in the out-of-plane direction [two-dimensional (2D) phonon transport]. We doped SnSe with bromine to make n-type SnSe crystals with the overlapping interlayer charge density (3D charge transport). A continuous phase transition increases the symmetry and diverges two conv...
Source: ScienceNOW - May 17, 2018 Category: Science Authors: Chang, C., Wu, M., He, D., Pei, Y., Wu, C.-F., Wu, X., Yu, H., Zhu, F., Wang, K., Chen, Y., Huang, L., Li, J.-F., He, J., Zhao, L.-D. Tags: Physics, Applied, Materials Science reports Source Type: news
Bringing MomTech to life: Pitt Engineering professor designs a gadget to help moms breastfeed
(University of Pittsburgh) Breast milk has many known health benefits, but breastfeeding is not always an option for moms, and many turn to pumping as an alternative. Katherine Hornbostel, assistant professor of mechanical engineering and materials science at the University of Pittsburgh Swanson School of Engineering, wanted to make this often cumbersome process easier. She decided to tackle the antiquated design of modern breast pumps and create a clever attachment that would make pumping more like nursing. (Source: EurekAlert! - Medicine and Health)
Source: EurekAlert! - Medicine and Health - May 15, 2018 Category: International Medicine & Public Health Source Type: news