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RESEARCH/RESEARCHERS Fe/Si nanoparticle acts as a “seed” and the medical implants. They have found that patterns in preheated crucibles and melt- Si filaments grow from the Fe/Si nanopar- Vit106 (Zr57Nb5Cu15.4Ni12.6Al10) foam ed. High-pressure argon gas was applied ticle surface. This approach produced shows compressive properties not unlike to the Vit106 surface to drive it into the wires with a distribution of diameters ductile aluminum foam, despite a lack of BaF2 pattern. After cooling, the Vit106/ ranging from 8–40 nm. In order to produce ductility in monolithic Vit106. Further- BaF2 composite was ground to a desired smaller-diameter wires, the researchers more, Vit106 contains neither precious size and the BaF2 was leached out using developed a post-synthesis approach. metals nor toxic beryllium, and shows nitric acid. Scanning electron microscope They used oxidation at elevated tempera- biocompatibility. images of Vit106 foams of 4.5 mm diame- ture to diffuse oxygen radially inward and As reported in the February 18 issue of ter and 8.7 mm height show 78% open shrink the Si crystalline core. Fractions Advanced Materials (p. 484, DOI: 10.1002/ porosity with pore sizes of 212–250 µm. were then separated according to the adma.200400897), the researchers pro- The thickness of all Vit106 struts is well wire diameter using centrifugal separa- duced samples by crushing optical-grade below 1 mm, where high bending ductili- tion. Using this method, the researchers BaF2 and sieving it to produce and select ty is expected. X-ray diffraction shows that produced a series of four crystalline Si 215–220 µm particles. These were then no crystalline phases were present in the nanowire samples whose most probable packed into graphite crucibles and sin- foam. The researchers concluded that diameters were 4.5 ± 0.2 nm, 6.5 ± 0.3 nm, tered at 1250°C for 10 h under high vacu- BMG foams can achieve high compressive 9.5 ± 0.3 nm, and 23.1 ± 0.7 nm. The um. The 7-mm-diameter patterns were ductility through strut bending, in sharp researchers probed the phonon bands in then placed in stainless steel crucibles and contrast to the brittle compressive behav- these nanowires using Raman spectros- vacuum-dried at 300°C for 30 min. Vit106 ior of BMG in monolithic form. copy at low enough laser intensity that charges were then combined with the BaF2 VIVEK RANJAN temperature broadening was not a factor. Comparison of the Raman spectra of FORFor MORE more RESEARCH research newsNEWS onON MaterialsMATERIALS Science, SCIENCE access . access the Materialsthe Materials Research Research Society Society Web Web site:site: these Si nanowires showed that with www.mrs.org/connectionswww.mrs.org/connections decreasing diameter, the first-order Raman band at ~520 cm–1 develops a Corrections noticeable asymmetry to lower frequen- MaterialsMRS Bulletin Issuesmisprinted in Solid the Free-Formingsponsors of Symposium LL in the report on the cy, and the peak position downshifts. 2004Symposium Materials LL Research brought Society together Fall discussions Meeting (addressingMRS Bulletin important30 [3] [March issues relat-2005] The researchers analyzed their results edp. to239). free-forming Support toand Symposium other parallel LL processing was given methods by the forArmy advanced Research materials. Office based on an asymmetric line-shape model The(United symposium States of opened America) with and a special the Engineering symposium andaddress Physical titled Sciences “Electrospraying Research developed by Richter with an adjustable WingsCouncil of (United Molecular Kingdom). Elephants” Following by John is Fenn,the corrected 2002 Nobel report. Laureate in chemistry. parameter (α) added to the theory that The presentation elucidated the electrospray technique and the significant advan- defines the width of the Gaussian phonon- tageMaterials in the use Issues for weighting in Solid large Free-Forming biomolecules. Several sessions followed, with confinement function. The researchers invitedSymposium papers LLfrom brought a host togetherof eminent discussions scientists addressing from around important the world. issues The related first found that this parameter is not sensitive sessionto free-forming covered andthe broadother parallelfield of solidprocessing free-forming, methods with for advancedM. Edirisinghe materials. (Queen The to diameter over the 4–25 nm range if they Mary,symposium Univ. of opened London), with B. Derbya special (Univ. address of Manchester), titled “Electrospraying A. Safari (Rutgers), Wings and of took into account the measured diameter L.Molecular Iuliano (Univ. Elephants” Modena, by JohnItaly) Fenn presenting (Virginia talks Commonwealth on jet-based and Univ.), other 2002 advanced Nobel distribution. This result is contradictory to materials-formingLaureate in Chemistry. methods The presentation at both the elucidatednano- and the micrometer electrospray scales. technique The follow-and the the large range of reported α values. While ingsignificant session advantage covered 3D in fabricationthe use for weighingand applications large biomolecules. (J. Beaman, Several Univ. ofsessions Texas; fol- E. attributing the difference to a variety of Sachs,lowed, MIT; with Y.invited Gogotsi papers et al.,from Drexel). a host ofThe eminent second scientists day started from with around a session the world. on unknown conditions, the researchers said processingThe first session and fabricationcovered the ofbroad advanced field of materials solid free-forming, (G. Babini with and M. L. Edirisinghe Settineri, that the thickness and nature of the oxide Politecnico(Queen Mary, di Univ.Torino, of London),Italy). The B. Derbyfinal session(Univ. of addressed Manchester electrohydrodynamic and UMIST), A. Safari coating on the wire might also impact the atomization(Rutgers), and and L. Iuliano applications (Politecnico (J. Dedi Torino)la Mora, presenting Yale; K.-L. talks Choy,on jet-based Univ. and of phonon confinement. That is, they said, the Nottingham;other advanced M. materials-formingBrenner, Harvard, methods and I. Loscertales, at both the Univ. nano- Malaga). and micrometer scales. phonon in the crystalline core of the TheSymposium following Support: session ARL covered and Queen 3D Mary, fabrication Univ. of andLondon. applications (J. Beaman, Univ. of nanowire has to decay into phonons in the Texas; E. Sachs, MIT; oxide shell. Therefore, the researchers sug- Y. Gogotsi et al., Drexel). gested future experiments on hydrogen- The second day started with terminated Si nanowires to see how hydro- a session on processing and gen termination affects the value of the fabrication of advanced confinement parameter. materials (G. Babini and TAO XU L. Settineri, Politecnico di Torino). The final session Bulk Metallic Glass Foam addressed electrohydrody- Achieves High Ductility namic atomization and Metallic foams are currently used as applications (J. De la ultralight structural materials. Bulk metal- Mora, Yale; K.L. Choy, lic glasses (BMGs) show exceptional Univ. of Nottingham; strength and elasticity, in addition to other M. Brenner, Harvard, favorable properties, rendering them also and I. Loscertales, Univ. of useful for structural applications and Malaga). potentially for biocompatible implants. Symposium Support: Army A.H. Brothers and D.C. Dunand of North- Research Office (United States of America) and the Engineering western University considered, then, Nobel Laureate John Fenn (left) with Suwan whether BMG foams offer unique oppor- and Physical Sciences Research Council (United Kingdom). Jayasinghe, lead symposium organizer. tunities in engineering structures or bio- MRS BULLETIN • VOLUME 30 • APRIL 2005 267 Downloaded from https://www.cambridge.org/core. IP address: 170.106.202.8, on 30 Sep 2021 at 15:03:07, subject to the Cambridge Core terms of use, available at https://www.cambridge.org/core/terms. https://doi.org/10.1557/mrs2005.89 RESEARCH/RESEARCHERS News of MRS Members/Materials Researchers Dan David Prize Recognizes Materials Scientists’ Impact on the Future This year, the Dan David Prize has ous novel biomate- given a $1 million award for achieve- rials; C.N.R. Rao ments in materials science, recognizing (Jawaharlal Nehru researchers’ outstanding scientific im- Centre, India), for his pact on the future. sustained record of Headquartered at Tel Aviv Univer- scientific accomplish- sity, Israel, the Dan David Prize annual- ments in solid-state ly awards three prizes for achievements and materials chem- Robert Langer C.N.R. Rao George Whitesides having an outstanding scientific, techno- istry; and George logical, cultural, or social impact on the Whitesides (Harvard University, USA) Dan David, is funded by the Dan David world. Each year, one field is chosen for for having bridged the fields of chem- Foundation. David, inventor of auto- each of three time dimensions—past, istry, chemical engineering, and biology matic photo booths, is president of present, and future. The laureates for a to new heights through the develop- Photo Me International. given year are chosen from these fields. ment of novel functional materials and The Dan David Prize recognizes For 2005, materials science was cho- systems. work in different fields each year. On sen to represent the future time dimen- To foster the next generation of schol- the announcement of the 2005 recipi- sion. Following a meeting of its distin- ars, each laureate is to donate $15,000 as ents, David said, “This year, the win- guished Board at the University of La a scholarship to