RESEARCH/RESEARCHERS

Electron CrystallographyProvides Accurate StructuralDetermination of TinSe4

In an article published in the July 11issue of Nature, researchers reported thesuccessful use of electron crystallographyto determine with 0.02 A accuracy thestructure for the compound TinSe4. Withsingle crystals too small to be determinedby x-ray crystallography and difficultiesusing powder diffraction, the compoundwas analyzed by electron crystallographywhich, in the past, suffered from compli-cated quantitative analysis due to dynami-cal effects. However, a research team fromMax-Planck-Institut fiir Festkoperfor-schung, Stockholm University, and LundUniversity took a sample size of 10,000unit cells for electron diffraction and con-cluded a structure of TinSe4 in which theTi atoms are part of condensed metal octa-hedra and the Se atoms are surrounded byTi atoms forming trigonal prisms. Theresearchers report that every second layerconsists of alternating strings of two andfour condensed octahedra chains. Theyfurther report the crystallographic K-valueof 14.7% which represents only a minorinfluence of dynamical effects on the dif-fraction amplitudes.

Portable Soil Analyzer SpeedsUp Search for Contaminants

Researchers at Los Alamos NationalLaboratory have developed a method forlocating contaminated soils using a laser-based "backpack" system that electroni-cally analyzes contaminants in the soils.The portable unit, co-designed by DavidCremers and Monty Ferris of AdvancedChemical Diagnostic and InstrumentationGroup, focuses infrared laser pulses on asoil sample and creates a series of sparksthat cause the soil to heat rapidly andemit light. The unit then analyzes thespectrum of the emitted light to deter-mine whether the soil is contaminated.

When the laser pulse hits the soil, a sparkis produced, vaporizing a small amount ofsoil and creating a plasma. The unit thencollects light from the plasma and passes itthrough a prism, constructing a spectralsignature from which elements can bedetermined. The spectral results are ana-lyzed electronically. The entire process,lasting 0.1 ns, is called laser-induced break-down spectroscopy, or LIBS. The proce-dure repeats in three-second intervals.

"The light is emitted in a specific pat-tern for each atom and these patterns areanalyzed to identify contaminants," saidCremers.

The device, about the size of a cosmeticcase which can be worn on a person'sback, was developed to rapidly screensoils for a few selected contaminants,such as lead, beryllium, and barium.

Ferris said that the treatment of contami-nated soil is expensive and time-consum-ing, but workers in the field can screen anarea for contamination rapidly with thebackpack unit and map areas of high conta-mination. With LIBS, workers can performmeasurements in the field and not lose timewaiting for laboratory analysis. Volumes ofwaste are reduced because workers knowwhere to dig rather than having to guess.Also, using the backpack unit, soils can beanalyzed in locations that are not accessiblewith other analytical techniques.

Chinese Academy of ScienceInducts Ching Wu Chu

Director of the Texas Center for Super-conductivity, Ching Wu (Paul) Chu, apioneer in high-temperature supercon-ductivity, was inducted into the ChineseAcademy of Science (CAS) during theorganization's recent conference inBeijing. According to CAS, Chu has madesubstantial contributions to science inChina and throughout world.

"It is indeed a special honor for me tojoin this small group of distinguished for-eign scientists recognized by the mostpopulous country on earth. It is apparentthat friendship between two countriescan be advanced through scientific coop-eration and exchange," Chu said.

In 1987, Chu discovered a material thatsuperconducts at 95.9 K. At this tempera-ture, the superconductor can be cooledinexpensively with liquid nitrogen. His dis-covery made this technology practical andbrought it into the mainstream of science.

"I have no doubt that superconductivi-ty will touch every aspect of our lives thatis touched by electricity," Chu said. "I'dlike to see commercial projects come outof the center."

CAS began inducting foreign membersin 1994. To date, 24 have been selected.

Chu is also a member of the U. S.National Academy of Sciences and theThird World Academy of Sciences.

Stress-Strain Microprobe toAssess Aging of Nuclear PowerPlants

Nuclear power plants worldwide areaging, and with age comes deterioration.Current and planned nuclear power plantaging management practices are designedto identify and address this deterioration

before it becomes a threat to plant safety.However, many of the practices are elab-orate and expensive.

K. Linga Murty, professor of nuclearengineering at North Carolina StateUniversity, is developing a method thatquickly and efficiently assesses the condi-tion and life expectancy of various metal-lic components in the power plant. He isadapting a recently developed stress-strain microprobe to test nuclear powerplant components. The microprobe canbe used to determine the degree of dam-age that has occurred without causingharm to the structure.

Murty said that, while pressure vesselsare made of low alloy steels and startwith good ductility and toughness, expo-sure to radiation causes brittleness. Steel,the material used to make the reactor ves-sel, becomes more prone to fracture whenexposed to radiation. Also, the steel partsare welded together, and the weld zoneof the vessel is relatively more sensitive toradiation damage.

The stress-strain microprobe system isbased on the automated ball indentation(ABI) technique, which involves loweringa small spherical indentation device intothe reactor and gathering data with noharm to the vessel. The device measuresforce and depth of penetration and feedsthis information to a computer, which cal-culates the amount of stress and strain atthe site. With this information, utilitiesand other reactor operators can deter-mine how much the components—suchas pipes, pressure vessels, and turbineblades—have deteriorated and how longthey will remain usable.

When the plants reach their design life,officials must decide whether to shut themdown, thermally anneal them, which willrestore some of the toughness, or replacethe vessels.

"The Department of Energy and utilitycompanies are planning thermal annealingof some power plants," Murty said. "There-fore, we will need to know if we have re-covered the key mechanical properties."

According to Murty, no methods existnow to do this well. A second potentialuse, then, for the ABI technique is to mea-sure the mechanical properties of the ves-sel materials before and after annealing.He anticipates that his method will quanti-fy both the improvement in ductility andthe recovery of mechanical properties.

Murty will compare his results with datafrom conventional methods to confirm thatABI is as good as destructive tests on sur-veillance specimens but more easilyapplied to power plants in operation.

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RESEARCH/RESEARCHERS

13 Scientists Receive NationalMedal of Science and NationalMedal of Technology

President Clinton announced the 1996recipients of the United States' highestscience and technology honors, theNational Medal of Science and theNational Medal of Technology.

In the field of materials research, C.Kumar N. Patel, vice chancellor forresearch, University of California—LosAngeles, received the 1996 National Medalof Science for his invention of the carbondioxide laser, a major scientific and techno-logical breakthrough which continues to bean important tool in manufacturing, med-ical treatment, scientific investigations, andmaterials processing. His carbon dioxidelaser also led to the creation of new genera-tions of lasers and laser systems. The otherrecipients are Wallace S. Broecker (New-berry Professor of Geology, Lamont-Doherty Earth Observatory at ColumbiaUniversity, Palisades, New York), NormanDavidson (Norman W. Chandler ProfessorEmeritus and executive officer of theDivision of Biology at the CaliforniaInstitute of Technology in Pasadena,California), James L. Flanagan (Director of

the Center for Computer Aids forIndustrial Productivity and Vice Presidentfor Research at Rutgers University inPiscataway, New Jersey), Richard M. Karp(professor, Department of ComputerScience and Engineering at the Universityof Washington, Seattle, Washington), RuthPatrick (Francis Boyer Chair of Limnology,Academy of Natural Sciences, Philadel-phia, Pennsylvania), Paul A. Samuelson(economist and institute professor emeri-tus, Massachusetts Institute of Technology,Cambridge, Massachusetts), and StephenSmale (mathematician and professor emer-itus, University of California—Berkeley.

The 1996 National Medal of Technologyrecipients are Charles H. Kaman, president,chair, and CEO, Kaman Corporation,Bloomfield, Connecticut, for his pioneeringwork in helicopter technology and for mak-ing present-day helicopters more stable andeasier to fly and for many other innovationsincluding artificial intelligence in medicineand electromagnetic motors to run cleanerpublic transit buses; Stephanie LouiseKwolek, consultant and former researchassociate, DuPont Company, Wilmington,Delaware, for her contributions in the dis-covery and development of high-perfor-

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mance aramid fibers which are used inproducts such as lightweight bullet-proofvests and fiber optic cables; James C.Morgan, chair and CEO, Applied Materials,Inc., Santa Clara, California, for his visionand leadership in the development of theU.S. semiconductor manufacturing equip-ment industry; Peter H. Rose, president,Krytek Corporation, Danvers, Massachu-setts, for his leadership in the developmentand commercialization of ion implantationproducts, which are necessary for the pro-duction of modern semiconductors; andJohnson & Johnson, New Brunswick, NewJersey, for a century of innovation in theresearch, development, and commercializa-tion of products, including the first dispos-able contact lens.

R&D Magazine Announces100 Awards

The trade journal R&D Magazineannounced its 1996 awards for the top100 technological achievements. Brook-haven National Laboratory was namedfor its plasma window, a device useful forelectron-beam welding, recovering scrapmetal through electron-beam melting,using industrial processes for makingnew materials or modifying existingmaterials, and transmitting beams of radi-ation for experiments in advanced syn-chrotron light sources. Developed by AdyHershcovitch, the plasma window is anionized gas that separates atmosphericpressure from a vacuum. At 12,000cC, theplasma window is about 300 times as hotas the air at room temperature. Thisintense heat makes the ionized atoms andmolecules move around faster and collidemore often with air molecules, thus stop-ping most of them when they try to passthrough the plasma window. Since theplasma window matches atmosphericpressure with only one-fortieth its densi-ty, less air pressure can escape from itinto the vacuum.

Researchers at Sandia National Labora-tories were recognized for developingglasses out of phosphate rather than sili-cate to hermetically seal aluminum elec-tronic components, useful for automobileand aerospace companies. The molecularstructure of phosphate-based glass permitsit to flow at much lower temperatures thansilicate-based glass so that it is complimen-tary to the use of aluminum. Researchershave modified the molecular structure ofphosphate glass through the incorporationof aluminum oxide, maintaining the chem-ical durability of the glass.

Several awards went to the develop-ment of new materials. Sandy Krezmien-Funk (Owens-Corning) developed glass

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RESEARCH/RESEARCHERS

fibers to replace synthetic fibers. Fabrica-ted by fusing two forms of glass into asingle filament, the MIRAFLEX fiber actsas a fire-retardant material and can beused as insulation for speakers and elec-trical products, among other applications.

Researchers at Gel Sciences and theMassachusetts Institute of Technologydeveloped smart hydrogels and smartlyogels, a family of gel materials designedwith smart solvophobic and solvophilicforces that alter their properties pre-dictably due to environmental influences.Among other applications, smart hydro-gels can be used for drug delivery withinthe body.

In response to a need to remove heatfrom circuits in electronic packaging,researchers at Applied Sciences devel-oped a substrate of materials calledBlacklce, demonstrating thermal-expan-sion properties that perform better thanpolymers, ceramics, various metals, andsome emerging composites.

Awards went to American Supercon-ductor Corp. for its high-temperaturesuperconductor fabrication technologythat uses a composite that has filamentsof a ceramic superconductor embeddedin a metal matrix; Pacific Northwest foran electrochemical process that operatesat low temperature and ambient pressureand uses a recyclable electrocatalyst forthe economical treatment of hazardoussolid and liquid wastes; Oak RidgeNational Laboratory for thin-film re-chargeable lithium batteries less than 10μ^zx thick consisting of an electrolytemade of the ceramic material lithiumphosphorus oxynitride rather than of anorganic liquid; Matsushita Electrical

Recently AnnouncedCRADAs

Los Alamos National Laboratory(Los Alamos, New Mexico) andTriton Thalassic Technologies Inc.(T3I) (Ridgefield, Connecticut) signeda nine-month, cost-shared agreementof $103,000 to develop an ultravioletfluid treatment system.

Appliance Recycling Centers ofAmerica, Inc. (ARCA) (Minneapois,Minnesota) and Argonne NationalLaboratory (Argonne, Illinois) signedan $800,000, 16-month agreement tostudy economical ways to separateand recover highly pure plastics, suchas acrylonitrile-butadiene-styrene(ABS) and high-impact polystyrene(HIPS), from shredded householdappliances.

Industrial Co. (Japan) for a red semicon-ductor laser consisting of a saturableabsorbing layer using metal oxide growthtechniques; and to scientists at SRICO,Inc., Army Research Laboratory, and theUniversity of Cincinnati for a photonicelectric field sensor made of dielectricmaterials that reduce the sensor's suscep-tibility to electric noise, improving itsaccuracy over other devices.

Other awards include laboratory-on-a-chip developed by Oak Ridge NationalLaboratory (see MRS Bulletin, April 1995for more details); the integration of micro-machines with electronics in manufactur-ing processes (see MRS Bulletin, June1996) and a low-temperature/pressureprocess to produce aerogels in bulk andthin-film form (see MRS Bulletin, August1995), both by Sandia National Labora-tories; and the magnetic flux imaging sys-tem by Argonne National Laboratory (seeMRS Bulletin, September 1995).

For more details on all of the awards,see R&D Magazine, September 1996,Volume 38, No. 10. The 1997 entry formswill be available November 1 by fax 847-390-2618, via the World Wide Web athttp://www.rdmag.com, and in upcom-ing issues of R&D.

Hecker to Receive NavyLeague Award

Siegfried Hecker, director of Los AlamosNational Laboratory, will receive the NavyLeague New York Council's RooseveltsGold Medal for Science Award.

Retired Navy Admiral S. Robert Foley,president of Raytheon, Japan, nominatedHecker for his leadership in laboratoryprograms such as the Trident program,Russian collaborations, new satellitedevelopments, advanced computer tech-nologies, AIDS research, genome studies,and the breakthroughs in neutrinoresearch and superconductivity.

"Under Sig Hecker's leadership anddirection, Los Alamos National Labora-tory has made and will continue to makedynamic and momentous contributionsnot only in science and technology, but toour national defense," Foley said in thenomination letter.

The 10-year-old Roosevelts Gold Medalaward honors an individual, corporation,or institution for extraordinary contribu-tions through science to the security ofAmerica, according to the Navy League.The award was named for both Theodoreand Franklin Delano Roosevelt, both for-mer New York Navy League members,who contributed to the U.S. Navy fleet'smodernization.

The Navy League was formed in 1902

with cooperation and funding fromTheodore Roosevelt. It serves as a civilianorganization that speaks for the Navyand serves to educate and motivateAmericans to support maritime capabili-ties, services, and personnel.

Hecker will receive the medal at a formaldinner in New York on November 20.

Silver Grown Epitaxially onGallium Arsenide

Researchers at the University of Texas—Austin have synthesized a flat epitaxial Agfilm on a GaAs (110) surface. At a temper-ature of 135 K, nominally 15 A of Ag wasdeposited on a GaAs substrate, forming adense nanocluster film. When annealed atroom temperature, "a perfectly flat, epitax-ial, single-crystal film with uniform thick-ness was formed," according to theresearchers. The films did have some pits,but for a film deposited at temperature,complete islanding occurs. Based on thepit depths, the film thickness was ~15 A,with a close-packed (111) structure. Intheir article published in the July 12 issueof Science, the researchers said that thestructure is "modulated by a 'silver mean'quasi-periodic sequence" along the [001]direction of the substrate, appearing asstripes with spacings of -13 A and -17 A(referred to as short segment and long seg-ment) in correspondence to five and sevenatomic row spacings in Ag crystals. Theresearchers reported that a scanning tun-neling microscopic image shows that thesequence follows that of the silver meanexcept at one location that is identified asan extra long segment and at another loca-tion that represents a missing short seg-ment. The researchers said, "These twolocations can be considered as the posi-tions where the silver mean sequence isbroken." The average coherent lengthbetween broken sequences is -100 A. Theresearchers concluded that the flat filmforms at a critical thickness of -15 A, butthey cannot explain why. For films nomi-nally thinner than 15 A, the annealed filmformed flat-topped islands of 11-15 Athickness. For thicker films, excess Agformed islands on top of a 15-A-thick con-tinuous layer.

News Briefs of Special ScienceReports from The GermanResearch Service• By bombarding atoms with a highlyenergized beam of charged atomic nucleiin a heavy-ion accelerator system,researchers at the Society for Heavy-IonResearch in Darmstadt have produced,for a brief moment, an element withatomic number 112. Peter Armbruster led

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RESEARCH/RESEARCHERS

an international team of scientists whobeamed heavy zinc ions onto a foil of leadatoms as a target. The fusion of zinc, withatomic number 30, and lead, with atomicnumber 82, synthesized into the elementwith atomic number 112.• Udo Schwertmann led a team of scien-tists from the Faculty of Soil Science at theTechnical University of Munich-Weihen-stephan in the discovery of a naturalsource of iron hydroxysulfate in Pfitz-cherjoch in South Tyrol. The InternationalMinerological Association has officiallynamed the mineral "Schwertmannite."

Hahn Selected for Medal ofExcellence

H. Thomas Hahn, Hughes AircraftCompany Chair in Manufacturing Engi-neering at the University of California—Los Angeles, has been selected to receivethe 1996 Medal of Excellence in CompositeMaterials, given annually by the Uni-versity of Delaware Center for CompositeMaterials. According to Tsu-Wei Chou,Medal Award Committee Chair, Hahn"has been a leading contributor to the sci-

ence and technology of composites fornearly a quarter of a century. His scholarlywork in the mechanics and manufacturingscience of composites will have lastingimpact on our knowledge of the field."

One of Harm's major accomplishmentswas founding the Integrated Manufac-turing Engineering Program at UCLA.The Program's focus is on the integrationof design, manufacturing, business, andmanagement.

Hahn's areas of technical expertiseinclude composites manufacturing andprocessing, composites design, fracture andfatigue, concurrent engineering, and rapidprototyping. He has published close to 175papers and chapters. His current efforts aredirected toward the integration of compos-ites manufacturing with traditional manu-facturing through rapid prototyping.

Among his past and current profes-sional activities and accomplishments,Hahn is President of the AmericanSociety for Composites, an ASME Fellow,and has been a member of the NRCNational Materials Advisory Board com-mittees and the Technical Review Board

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Two Advances OvercomeObstacles to EUV LithographyUse in Fabricating ComputerChips

Two advances made by researchers atLawrence Livermore National Laboratoryappear to overcome two obstacles in thedevelopment of using extreme ultravioletlight (EUV) lithography to make comput-er chips. EUV lithography would allowcomputer chip makers to work with lightwavelengths 20 times shorter thantoday's technology, reducing line widthsor feature sizes on chips from 0.35 pm to0.1 pm and below.

The advances were made in two key areas:• a 300,000-fold reduction in the numberof defects for the multilayer coated reflec-tive masks used to transfer circuit pat-terns onto silicon wafers, or chips;• a critical 20- to 50-fold improvement inaccuracy for measuring the surfaceshapes of optical components used in thelithography process.

The reduced mask defects spring froman ion beam sputter deposition system.Current methods to make EUV multilay-er masks use a technique called mag-netron sputtering that produces about10,000 defects in a square centimeter. Theion beam sputter deposition systemyields only three defects in 100 cm. ForEUV lithography to be ready for commer-cial production, this defect ratio wouldneed to be reduced further.

The second advance, by optical physi-cist Gary Sommargren, is an instrumentthat significantly improves the measure-ment accuracy of spherical and nonspher-ical optical surfaces. Don Kania, deputyAMP leader, said, "Without the ability tomeasure accurately these asphericaloptics, it is impossible to build the opticalsystems required for EUV lithography." D

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