A QUARTERLY RESEARCH & DEVELOPMENT JOURNAL Investigating VOLUME … · 2020-02-27 · project with...

A QUARTERLY RESEARCH & DEVELOPMENT JOURNALVOLUME 5, NO. 3

InvestigatingColumbia

Tailoring human implants

New materialstaking their cues from nature

S A N D I A T E C H N O L O G Y

Sandia Technology is a quarterly journal published bySandia National Laboratories. Sandia is a multiprogramengineering and science laboratory operated by SandiaCorporation, a Lockheed Martin company, for theDepartment of Energy. With main facilities in Albuquerque,New Mexico, and Livermore, California, Sandia has broad-based research and development responsibilities for nuclearweapons, arms control, energy, the environment, economiccompetitiveness, and other areas of importance to the needsof the nation. The Laboratories’ principal mission is tosupport national defense policies, by ensuring that thenuclear weapon stockpile meets the highest standards ofsafety, reliability, security, use control, and militaryperformance. For more information on Sandia, see ourWeb site at http://www.sandia.gov.

To request additional copies or to subscribe, contact:Michelle FlemingMedia Relations Communications Dept.MS 0165Sandia National LaboratoriesP.O. Box 5800Albuquerque, NM 87185-0165Voice: (505) 844-4902Fax: (505) 844-1392e-mail: [email protected]

Sandia Technology Staff:Laboratory Directed Research & Development Program Manager: Henry WestrichMedia Relations and Communications Department Manager: Bruce FetzerEditor: Will Keener, Sandia National LaboratoriesWriting: Chris Burroughs, Neal Singer, Michael Padilla, and Nigel HeyPhotography: Randy J. Montoya, Chris Burroughs, Sandia National Laboratories, Norman Johnson PhotographyDesign: Douglas Prout, Technically Write

What is ?

Sandia's world-class science, technology, andengineering work define the Labs’ value to thenation. These capabilities must remain on the cuttingedge, because the security of the U.S. dependsdirectly upon them. Sandia's Laboratory DirectedResearch and Development ( ) Programprovides the flexibility to invest in long-term, high-risk, and potentially high-payoff research anddevelopment that stretch the Labs’ science andtechnology capabilities. supports Sandia's four primary strategicbusiness objectives: nuclear weapons;nonproliferation and materials assessment; energyand infrastructure assurance; and militarytechnologies and applications; and an emergingstrategic objective in homeland security. alsopromotes creative and innovative research anddevelopment by funding projects that arediscretionary, short term, and often high risk,attracting exceptional research talent from acrossmany disciplines. When the symbol appears in this issue,it indicates that at some state in the history of thetechnology or program, funding played acritical role.

On the Cover:

Researchers at Sandia’s Visualization Laboratory discuss a computersimulation and analysis showing the impact of a foam piece along theleading edge of the space shuttle wing. These analyses and subsequentreal-world testing helped convince NASA’s Columbia Accident InvestigationBoard that insulating foam, striking the wing during launch, was thelikely cause of damage that led to the shuttle’s loss. Story on page 2.(Photo by Randy Montoya.)

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Dear Readers, This issue of SandiaTechnology begins with a look atthe Labs’ contributions to ournational understanding of whatwent wrong February 1, 2003,when the Space Shuttle Columbiaplunged from the sky. It detailswhat Sandia did technically, butit reveals little of the personalefforts of team members, whoimmersed themselves in thisintense effort for several months’time. In the scheme of things,Sandia played a small part on thestage of a global drama, but thework of these researchers iscertainly worthy of recognition. Following the Columbia article,reported by Sandia’s MichaelPadilla, are two related pieces,summarizing the Labs’ efforts toprovide materials and to testtechnologies for next-generationlaunch vehicles. These efforts willhelp to make the U.S. spaceprogram safer and stronger. Other articles in this issuetouch on Sandia research in themedical, materials, riskvulnerability assessment, andenergy fields. Finally, the issuereviews some of the very best ofSandia’s technology develop-ments for the year, as judged byeditors of R&D Magazine. AmongSandia’s seven winning entrieswas a collaborative researchproject with industry andacademic colleagues on ExtremeUltraviolet Lithography. Seen asthe next wave in computer chipmanufacturing, this effort wassingled out by R&D Magazineeditors for one of its very topawards, the Editors’ Choice.

Will KeenerEditor

F R O M T H EEditor

T A B L E O FContents

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5

6

8

10

12

13

15

The Shuttle:A probable cause

Sandia developingultra-high-temperature ceramics

Sandia assists NASA’sHyTEx program

Tailoringhuman implants

New way to makewhite light

Sandia, GTI addressnatural gas supply security


Lowering thecost of wind energy

R&D 100 AwardsInside back cover

Fall Issue 2003

andia’s expertise in material andengineering science played a key role inhelping NASA determine the cause of theFebruary 1 space shuttle Columbia disaster.After five months’ work, Sandia analysesand experimental studies supported theColumbia Accident Investigation Board’sposition that the most probable cause ofthe accident was damage to the wingleading edge caused by foam debris. Thedebris separated from the fuel tank andimpacted the orbiter wing during launch. Just four days after the disaster, Sandiapersonnel joined a team of engineers fromseveral NASA Centers and their contractorsto identify and evaluate credible damage

scenarios that might have led to theaccident. They analyzed data sent fromColumbia during reentry, and they reviewedthe locations of orbiter debris recoveredacross Texas during the first month afterthe accident. Information on Columbiadamage scenarios, configuration, andmaterial properties was sent back toAlbuquerque, where engineering analyseswere performed on Sandia’s big computers. Working in partnership with NASAanalysts, Sandians assessed the credibilityof possible damage to Columbia that couldhave occurred prior to reentry and couldhave resulted in orbiter breakup duringreentry. The researchers used computational

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Sandia researchersfaced a very skeptical

community ofengineers and

scientists whenthey predicted

that scraps of foamcould penetratea layer of tough

composite material,causing damage that

led to Columbia’sbreak-up over Texas.Working closely withNASA engineers and

contractors, theresearchers set

about convincingthemselves and

their colleagues withreal-world materials

testing andsupercomputer

simulations.

The Shuttle :A probable cause

S

Columbia

Tom Bickel, director of Sandia's EngineeringSciences Center, with samples of foam andshuttle tile, and a section of the compositeleading edge of the shuttle wing.(Photo by Randy Montoya.)

fluid dynamics (CFD) and rarefied gasdynamic computer codes to simulate theorbiter at various altitudes along thetrajectory. Other codes, called aerothermo-dynamic codes, were used to predict the heattransfer for various damaged wingconfigurations. These codes calculated thethermal and fluid flow properties of plumes,simulating hot gas entering the wing throughdamage sites. “The difficult part of our work wasrealizing that many damage scenarios wereconsistent with the limited data telemeteredfrom Columbia during reentry,” said BasilHassan of Sandia’s Engineering SciencesCenter. “More than one damage scenario

could match the data. Our team wanted touse analysis to eliminate as many scenariosas possible and then focus on the remainingones that seemed the most plausible.” WhenColumbia’s flight recorder was located latein March, the investigation team received awealth of additional information thateliminated several accident scenarios anddirected its attention to the left wing leadingedge and thermal tiles.

Little agreement

Despite video images of foam strikingColumbia’s left wing during lift-off, therewas no agreement among investigators thatthe foam could cause sufficient damage toprecipitate the accident. As a result, NASAplanned experiments at Southwest ResearchInstitute (SwRI) in San Antonio, Texas, toassess foam impact damage. In lateFebruary, NASA asked Sandia for foamimpact analysis support to guide the SwRItests, which used full-scale mockups of partsof the wing. Sandia began preparingcomputational models of foam impact ontothe wing’s reinforced carbon composite(RCC) leading edge and lower surfacethermal protection system (TPS) tiles. During the next three months, Sandiaexperimentalists in California and NewMexico supported the foam impact analystsby providing material characterization datafor RCC, TPS tiles, and foam. Data fromthese material characterization experimentsbecame a major Sandia contribution to the

accident investigation.They were used by all of

the NASA foam impactanalysis teams.

Sandia’s foam impactcomputational results

suggested that foamimpacting the lower

wing tiles would notcause much

damage. Butimpacts to the

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“Our teamwanted to use

analysis toeliminate as many

scenarios aspossible and then

focus on theremaining ones

that seemed themost plausible.”

Basil Hassan of Sandia’sEngineering Sciences Center


Sandia researchers discuss a computer model analyzing a foam block impacting the leading edge of theshuttle wing. (Photo by Randy Montoya.)

wing’s leading edge could actually damageand potentially penetrate the RCC material.“We faced a very skeptical community,” saidTom Bickel, who led the Sandia team. Thisskepticism would remain until full-scaletests of foam impacting a mockup of theorbiter’s leading edge proved the point. SwRI foam impact tests at different winglocations produced damage in the RCCleading edge panels that ranged fromlocalized cracking to full breakage. The mostdramatic test at SwRI produced a 16-inchdiameter hole in the lower half of a leadingedge panel of the orbiter. Such damage wouldbe catastrophic, allowing high-temperaturegases to enter the wing and melt thealuminum wing structure during reentry.These data convinced all investigators that

the most probable damage location was theleading edge of the left wing. The Columbia Accident InvestigationBoard subsequently acknowledged the RCCleading edge foam impact scenario as themost likely cause of the disaster. Its fullreport is scheduled for release at the end ofthe year.

Media Contact: Michael Padilla,[email protected], (505) 284-5325

Technical Contact: Tom Bickel,[email protected], (505) 845-9301

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A) View from ‘inside’ the wing area,or a view opposite the impact side.B) View from ‘outside’ the wing,or in front of the wing leading edge(shows hole.)C) View from ‘outside’ the wing, ina perspective that shows the foamcoming at you, as it slides down theleading edge. All images are from analyses ofSouthwest Research Institute’s testof a 1.9 pound piece of foam at775 feet/second impact. All plotsare at 2.4 milli-seconds of analysis time,or 0.0024 second.

A B C

Invaluable expertise“Sandia’s expertise in the areas of impact testing

and modeling, material testing, non-continuumaerodynamics, and thermal analysis has beeninvaluable to our investigation teams. The cooperativeeffort and sharing ofideas, test methods,and analytical toolshave been beneficial toboth our organizations.”

William ReaddyAssociate Administratorfor Space, NationalAeronautics andSpace Administration

Service in the national interest Sandia has been instrumental in assisting ininvestigating the cause of various national issuesincluding:

• Determining the cause of the 1989 turret explosion that killed 47 men aboard the USS Iowa.

• Supporting and helping guide the National Transportation Safety Board to confirm that the TWA Flight 800 accident of July 1997 most likely was the result of an unintended ignition of the fuel-air mixture in a fuel tank.

• Working in solving the Unabomber case in 1996 by assisting FBI and other agents during the search of the Unabomber’s cabin in Montana.

esearchers at Sandia NationalLaboratories are developing a newlightweight material to withstand ultra-hightemperatures on hypersonic vehicles, suchas the space shuttle. The ultra-high-temperature ceramics (UHTCs), created inSandia’s Advanced Materials Laboratory,can withstand up to 2000ºC (about 3,800ºF). Ron Loehman, a senior scientist inSandia’s Ceramic Materials, said results fromthe first seven months of the project haveexceeded his expectations. “We plan to havedemonstrated successful performance at thelab scale in another year with scale-up thenext year,” Loehman said.

Composite materials

UHTCs are composed of zirconiumdiboride (ZrB2) and hafnium diboride(HfB2), and composites of those ceramicswith silicon carbide. These ceramics areextremely hard and have high meltingtemperatures (3245ºC for ZrB2 and 3380ºCfor HfB2). When combined, the materialforms protective, oxidation-resistant coatings. “However, in their present state ofdevelopment, UHTCs have exhibited poorstrength and thermal shock behavior, adeficiency that has been attributed to inabilityto make them as fully dense ceramics withgood microstructures,” Loehman said.

Loehman said the initial evaluation ofUHTC specimens provided by the NASAThermal Protection Branch about a year agosuggests that the poor properties could betraced to errors in ceramic processing. During the first seven months, theresearchers made UHTCs, using both thezirconium and hafnium systems, that arenearly 100 percent dense. They havefavorable microstructures, as indicated bypreliminary electron microscopicexamination. In addition, the researchershave hot pressed UHTCs with a much widerrange of silicon carbide contents thanever before. This availability of a range ofcompositions and microstructures will givesystem engineers added flexibility inoptimizing their designs.

Collaborations

The project is part of the Sandia ThermalProtection Materials Program and representsthe work of researchers at Sandia and theUniversity of New Mexico. Sandia’s David Kuntz said his primaryresponsibility is to design thermal protectionsystems, or heat shields, compute materialthermal response on high-speed flightvehicles, and to develop tools to improvethese capabilities.

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Sandia developing

ultra-high-temperature ceramicsRThermal

insulationmaterials for

sharp leadingedges on

hypersonicvehicles, like the

space shuttle,must be stable at

temperaturesnear 2000ºC.The materials

must resistevaporation,erosion, and

oxidation, andlimit the heat

transfer tosupport

structures.

Sandia researchers Ron Loehman, right, and Dale Zschieschecheck out material that can withstand twice the amount ofheat of a conventional piece of a shuttle tile.(Photo by Randy Montoya.)

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“If a vehicle flies fast enough to get hot,we analyze it,” Kuntz said. “Our tools consistof a set of computer codes that compute theflow field around a high-speed flight vehicle,the resultant heating on the surface of thevehicle, and the subsequent temperaturesand loss of the materials, which form thesurface of the vehicle.” Jill Glass (Sandia’s Ceramic MaterialsDepartment) works with high-temperaturemechanical properties and fracture analysis.Paul Kotula (Materials Characterizationdepartment) performs microstructural andmicrochemical analysis on the ceramicmaterials. Kotula applies software analysisto the characterization of hafnium andzirconium UHTCs. he looks at thesematerials at the micron and even smallerscales for problems that can adversely affecttheir mechanical properties. (The Automated eXpert Spectral ImageAnalysis (AXSIA) developed by Kotula andSandia’s Michael Keenan was recentlypatented and was a winner of a 2002 R&D100 award. For more on the 2003 winners,see inside back cover.)

Creative analysis

Boron and carbon are difficult to analyze,because they give off low-energy or softX-rays when excited with an electron beamas typically used for such analyses. Insteadof using X-ray analysis, the research teamhas developed analytical capabilities basedon electron energy-loss spectrometry todetermine amounts and distributions of thelight elements in UHTCs. Oxygen, in particular, is an importantimpurity since, in combination with thesilicon present in the UHTCs and otherimpurities, it can form glasses or other phasesthat typically can’t withstand the requiredhigh-operation temperatures and would meltor crack in service, causing the materialto fail. “If enough of the wrong contaminantsfind their way into the process, the materialwill have no high-temperature strength orstability,” Kotula said.

Media Contact: Michael Padilla, [email protected],(505) 284-5325

Technical Contact: Ron Loehman, [email protected],(505) 272-7601


If enough ofthe wrong

contaminantsfind their way

into the process,the material will

have no high-temperature

strength orstability.

Sandia National Laboratoriesresearchers are assisting with NASA’sHyTEx (Hypersonic TechnologyExperiment) program to benefit next-generation launch vehicles, following inthe footsteps of the space shuttle. With the first flight scheduled for May2005, HyTEx is expected to provide adedicated, timely, and cost-effectivemeans of advancing the readiness levelof vehicle system technologies throughflight demonstrations in a relevant reentryenvironment. Involvement in HyTEx is in keepingwith Sandia’s long-range goal ofdeveloping advanced technologiesand integrated capabilities for hypersonic

flight systems, applicable to a wide rangeof military and access-to-spacerequirements. David Keese, deputy director forStrike Systems in Sandia’s AerospaceSystems Development Center, said theNASA HyTEx technology flightdemonstration is a perfect fit withSandia’s goal of supporting the design,development, and demonstration of thenext generation of hypersonic vehicles.“Our most important role in the HyTExprogram is to use our integrated design,development, and flight experience toproduce a capability to obtain hypersonicflight evaluation of these newtechnologies,” Keese said.

Sandia assists NASA’s HyTEx program

Sandia’sAerospace

SystemsDevelopment

Center willdevelop the

HyTEx re-entrysystem.

He described four basicdesign challenges in theHyTEx program:

• Provide a robust — low-risk and effective

— vehicle to functionas a flying test-bed.

• Incorporate technologyexperiments into thistest-bed design in a fail-safe approach.

• Collect and transmitin-flight data from theseexperiments.

• Adapt the flight vehicledesign to a variety ofpotential boosterdesigns, including arecovery system thatwill allow post-flightexamination of theintegrated experiments.

Sandia’s next major steps in theproject involve developing detailed plansand organizing Sandia’s resources toproduce an actual flight system for theHyTEx proof-of-concept mission. Labsresearchers are also working to advancekey enabling technologies that will giveeven greater capabilities to programslike HyTEx in the future.

Mike Macha, HyTEx projectmanager, said he sees the project as anopportunity for Sandia to have asignificant impact on a spectrum ofemerging U.S. hypersonic technologyinitiatives. “There is a resurgent interestin developing a new generation ofvehicles for rapid, affordable access tospace,” Macha said. Fortunately, Sandia already has afoothold in a wide range of potentialhypersonic technology areas —

from high-temperature materials, torobust non-GPS-dependent navigationand guidance methods, to modelingand simulation capabilities. “One immediate major challenge isdeciding which subset of candidatetechnology areas to invest in,” Machasaid. “During the first year we have gonethrough a discovery phase that includesunderstanding the current level ofdevelopment and the time frame formaturation of these technologies.”

Media Contact: Michael [email protected], (505) 284-5325

Technical Contact: David [email protected], (505) 844-1899

Labs researchersare also working

to advancekey enabling

technologies thatwill give even

greater capabilitiesto programslike HyTEx in

the future.

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Mike Macha (left) and Mark Howard check out a scale model ofthe internal experiment assembly that will be flown on the HyTExreentry vehicle. The model was created by using a 3-D printer.(Photo by Randy Montoya.)


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t has been known for some time thatbone mass can be generated by encouragingcells to grow around three-dimensionalsynthetic structures, such as sponges that areimpregnated with a growth medium. Withtime, the body fills in the scaffold-likestructure with bone and blood vessels.Currently, however, it is difficult to producea tailor-made, individualized “scaffold” thatprecisely fits into the shape of a specificimplant site. Additionally, the sponge-likereplicas are weak and have uncontrolled andnon-optimized porous structures.

Researchers at the University of Illinoisare teaming with Sandia NationalLaboratories colleagues to find a solutionwith Robocasting. A computer model of animplant may be generated from a medicalscan of a region of damaged bone. Using acombination of Robocasting and precisemachining, researchers produce an implantthat fits perfectly into the damaged regionand promotes healing and growth of thesurrounding healthy bone.

The implant requires a mesh-likestructure with mechanical properties similarto living bone and made with a biocompatiblematerial. The Robocasting system is ideallysuited to precisely fabricate the mesh-likescaffolds out of a precursor ceramic material,hydroxyapatite. The hydroxyapatite scaffoldsare strong enough to remain in place untilnatural bone grows into and ultimatelyreplaces the scaffold. Approval for use inpeople is expected to be swift since the Foodand Drug Administration (FDA) has alreadyaccepted hydroxyapatite as a suitable bio-material for use in humans.

Testing the concept

Recently, at a hospital in Urbana,Illinois, an elderly woman was briefly fittedwith a Robocast scaffold to see if it fit herjaw as well as expected. She had lost mostof her teeth and much of the bone of herlower jaw and was about to undergo aconventional bone replacement procedure,using bone harvested from her pelvis. Theceramic implant — created a thousand milesaway at Sandia facilities in Albuquerque — was designed in great detail, from its overallshape to the inclusion of a nerve groove. Anearlier medical scan had enabled thegeneration of a computer-derived model ofan implant that would mate perfectly withthe healthy remaining bone. Surgicalexpertise was provided to give computerprogrammers the dimensions of “what shouldbe there but wasn’t.”

Once it is approved by the FDA, it’sbelieved that use of the ceramic scaffolding

The problem: howto create synthetic

weight-bearingscaffolds that will

encourage thegrowth of natural

bone, bloodvessels, and soft

tissue to repairdamaged bone

within thehuman body.

The solution: use

data from medicalCAT scans and

Robocastingtechnology to

create implantswith tailored

microstructuresand precise

macrostructures.


Tailoringhuman implants

I

Pain-saving device brings pleasure to creator: Sandia researcherJoe Cesarano admires the perfect fit of his team’s Robocastimplant set in the jawbone of a model skull.(Photo by Randy Montoya.)

with new technology

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technique would reduce the pain, recoverytime, and chances of infection of thoseneeding repair or augmentation of the jaw,skull, spine, or other bony areas. Otherbenefits include avoidance of longersurgeries, greater predictability of outcome,and eventually lower health care costs.

A patent for the implant process ispending. The original Sandia-patentedRobocasting process was conceived andbuilt to fashion defense components on abattlefield, instead of medical parts in ahospital. Robocasting also is being developedto form advanced catalyst supports toincrease chemical reactivity. The computer-controlled machine dispenses liquefiedceramic pastes, like toothpaste squeezedfrom a tube, to form shapes of varyingcomplexity along a prearranged path.

To create the simulated bonescaffolding, the machine dispensed ahydroxyapatite mixture in a child’s LincolnLog-like arrangement, in cross-laid sliverseach about as thick and as far apart as thediameters of ten human hairs. “Bone, bloodvessels, and collagen love to grow into astructure with pores of that size (about500 microns),” says Sandia scientist JoeCesarano. “The material becomes ahard-tissue scaffold for promoting newbone growth.”

Improving the process

The hospital experience helpeddemonstrate that scientists and doctors usingcomputer programs, modern communi-cations, and machines at large distances fromeach other can produce a prosthetic devicethat will fit virtually seamlessly in a patient’sbody. As University of Illinois surgeonMichael Goldwasser put it, “What we wantis a method by which I can see a patient inIllinois, transmit X-ray information tosomeone who can make a substitute partthat would have the porous properties thatwould allow bone to grow into it, yet bestrong enough for normal function.”

“Surgeons and patients would love toeliminate both the bone retrieval and implantpreparation processes,” adds Cesarano,whose team fashioned the demonstrationimplant. “This test showed we can makeartificial porous implants prior to surgerythat will fit perfectly into the damaged region.The reconstructive procedure would thenonly require attaching the implant and closingthe wound.

“There is nothing inherently expensiveabout either the materials or the process,”said Cesarano. However, delineating theexact dimensions of what the bone wouldhave looked like, were it healthy, currentlyrequires the potentially expensive presenceof a surgeon. Goldwasser looks forward tothe time when a simple and cost-effectivemethod could be used through electronicmeans. For example, a piece might quicklyand inexpensively take shape at a remotesite, if there were a computer-aided drawingprogram, by which the surgeon neededonly to begin the process by sketching theshape needed.

“We’ll see if the clinician, thebioresearcher, and the engineer can comeup with a method to implement it,”Goldwasser says.

Media Contact: Neal [email protected], (505) 845-7078

Technical Contact: Joe Cesarano [email protected], (505) 272-7624,

The computer-controlled

machinedispenses

liquefied ceramicpastes, liketoothpaste

squeezed from atube, to form

shapes of varyingcomplexity along aprearranged path.


Perfection regained: the perfect fit of the Sandia ceramic scaffolding in the model jaw also recreates theupper line of the original jawbone. The scaffold layerings, which criss-cross each other, expedite passageof new bone and blood vessels. (Photo by Randy Montoya.)

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n a different approach to creatingwhite light, a Sandia research group hasdeveloped the first solid-state, white light-emitting device that uses quantum dots. Inthe future, the use of quantum dots as light-emitting phosphors may represent a majorapplication of nanotechnology.

“Highly efficient, low-cost quantumdot-based lighting would represent arevolution in lighting technology throughnanoscience,” says Lauren Rohwer, principalSandia investigator. “Understanding thephysics of luminescence at the nanoscaleand applying this knowledge to developquantum dot-based light sources is the focusof this work.”

Conventional phosphors used influorescent lighting are not ideal for solid-state lighting, because they have poorabsorption in the near ultraviolet wavelengthrange. So researchers worldwide have beeninvestigating other chemical compounds fortheir suitability as phosphors for solid-statelighting.

The new Sandia approach is based onencapsulating semiconductor quantum dots— nanoparticles approximately one billionthof a meter in size — and engineering theirsurfaces so they efficiently emit visible lightwhen excited by near-ultraviolet (UV) light-emitting diodes (LEDs). The quantum dotsstrongly absorb light in the near UV range

Quantum dots:nanoscience

provides acontender in thequest for a high-

efficiency, low-costwhite light source. It

can come in othercolors, too.

New way to makewhite light

Lauren Rohwer displays the twosolid-state light-emitting devicesusing quantum dots her teamhas developed.(Photos by Randy Montoya.)

I

This nanophosphor-based device is

quite different froman alternative

approach basedupon growth of

blue-, green-, andred-emitting

semiconductormaterials that require

careful mixing toproduce white

illumination.

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and re-emit visible light that has its colordetermined by both dot size and surfacechemistry.

While the optical properties ofconventional bulk phosphor powders aredetermined solely by the phosphor’s chemicalcomposition, in quantum dots the opticalproperties such as light absorbance aredetermined by the size of the dot. Changingthe size produces dramatic changes in color.

Alternative approach

This nanophosphor-based device is quitedifferent from an alternative approach basedupon growth of blue-, green-, and red-emittingsemiconductor materials that require carefulmixing to produce white illumination. Efficiently extracting all three colors insuch a device requires costly chip designs,which likely cannot compete withconventional fluorescent lighting but can beattractive for more specialized lightingapplications.

Rohwer and the quantum dot team —Jess Wilcoxon, Stephen Woessner, BillieAbrams, Steven Thoma, and Arturo Sanchez— started on the project two-and-a-halfyears ago. “This accomplishmentbrings quantum dot technology fromthe laboratory demonstration phaseto a packaged component,” Rohwer says.

By making a key innovation in theencapsulation process, the teamachieved an increase in efficiencyfrom the 10-20 percent range to an amazing60 percent, Thoma says. While othersworking in the field of quantum dots havereported conversion efficiencies of nearly 50percent in dilute solutions, the Sandia teamis believed to be the first to make anencapsulated quantum dot device with suchhigh efficiencies.

Media Contact: Chris [email protected], (505) 844-0948

Technical Contact: Jerry [email protected], (505) 844-8402

Lauren Rohwer is theprincipal investigator ofa research teamdeveloping the firstsolid-state white light-emitting device usingquantum dots.

andia National Laboratoriesand GTI have agreed to worktogether over the next two yearsto address concerns about thesecurity, reliability, integrity, andresiliency of the nation’s naturalgas supply and delivery system.

“This coordinated effortwill require a strong, constructiverelationship among the naturalgas industry, government, thenation’s research laboratories, andacademia in the areas of policy,regulation, training, andtechnology development,” said John Riordan,GTI’s president and CEO, in announcingthe pact.

GTI is a leading energy research,development and training organization.

“This is an important agreementbetween two institutions ideally suited toimprove the security and reliability of thenatural gas infrastructure in this nation,” saidBob Eagan, Sandia vice president for Energy,Information and Infrastructure Surety. Theproject will tap into the science, technologyand engineering strengths at Sandia, he said.“It will allow us to use tools we havedeveloped as part of the NationalInfrastructure Simulation and AnalysisCenter as well.”

Sandia's role will involve developmentand application of a risk assessment approachfor physical protection of pipelines and gasstorage facilities. Adapting its experience inother industries, Sandia will also look atinterdependencies between natural gas

infrastructures and those involving electricpower and telecommunications, said DavidBorns, of the Labs’ Geophysical TechnologyDepartment.

Researchers at the Labs will look at thesecurity of information technologies used ingas pipeline control and in gas businesstransactions, he said. Sandia will also providetechnical advice about needed technologiesor processes as they are identified duringthe analysis and implementation stages.

Media Contact: Will [email protected], (505) 844-1690

TechnicalContact: David [email protected], (505) 844-7333

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America needs asecure and reliable

gas distributionsystem for the

future. Sandia anda private-sector

leader are teamingto see what’s

needed to makeit a reality.

Sandia, GTI addressnatural gas

supply securityS


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he physicaland chemical

principles behind theformation of natural materials

are helping Sandia’s scientists to developways of using environmentally benign

processes for producing nano-materials.The goal is to take tips from nature indevising synthetic routes to achieve structuralcontrol for reliable and scalable production.

Nanomaterials are likely to findapplications in microelectronic devices,chemical and biological sensing anddiagnosis, catalysis, and energy conversionand storage, including photovoltaic cells,batteries, capacitors, and hydrogen storagedevices. These structures could also havepotential for light-emitting display, drugdelivery and optical storage.

A group of scientists, mainly fromSandia’s Chemical Synthesis andNanomaterials Department, aim to preciselycontrol and predict a wide range of materialsproperties. These include composition,particle size and shape, crystalline structure,

orientation, particle morphology, surface andinterface chemistry. The team has alreadymade new chemical sensor devices withits materials.

The team has demonstrated completecontrol of where and how crystals are formed.The process they have developed selectivelyactivates the specific surface they desire togrow, and then spontaneously producescomplicated three-dimensional structuresthat cannot be formed by other means.

Controlling growth

Natural systems use sophisticated proteinmolecules to precisely control the growthdirection and structure of the biominerals.In general, the proteins play two importanttricks. First, they control where the mineralis deposited. Second, they control how theminerals are formed. In red abalone, a marinesnail, water-soluble proteins controlmineralization of calcium carbonate. Someof these proteins are responsible for theformation of calcium carbonate architectures

Complexmicromaterials

that look strikinglysimilar to diatoms

and seashellsare emergingfrom Sandia’s

nanotechnologylabs.


T

Jim Voigt, left, and Jun Liu discuss complex nanomaterials developed to mimic nature.(Photo by Chris Burroughs.)

– for example column-like calcite and plate-like aragonite. A highly orderednanocomposite formed of these mineralsconfers optimal mechanical properties tothe hard tissue.

The first step of the process is tounderstand and control the solutionchemistry. Studies of low-temperature, low-chemical-concentration conditions inaqueous environments are helping the teamcontrol the speed with which the materialsgrow from solution. This avoids theprecipitations commonly encountered.

Surface chemistry

Modifying the surface chemistry is oftenused to stimulate the formation of theminerals on specific locations. At othertimes, nanoparticles are used as nucleationseeds. Computer modeling helps understand

how the organic molecules bind tothe crystals.

One challenge now is to fundamentallyunderstand how organic molecules affectcrystal growth. Another is developinggeneral rules to guide the production of awide range of nanomaterials. The team isalso in the process of developing tools tocontrol the delivery, diffusion, and transportof the chemical species in reaction chambers,

Media Contact: Michael [email protected], (505) 284-5325

Technical Contact: Jun [email protected], (505) 845-5470

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Complex nanocrystals have beenprepared showing striking similaritieswith those observed in biominerals.(a) is the inner layer of a shell in red-abalone. (b) is synthetic zinc oxidecrystals. (c) is a diatom. (d) to (h) aredifferent types of synthetic silica crystals.The structure depends on the growthconditions and can be controlled.

Studies oflow-temperature,

low-chemical-concentrationconditions in

aqueous environ-ments are helping

the team controlthe speed with

which the materialsgrow from solution.

urrent wind turbines are cost effectivein very windy sites. The goal of theDepartment of Energy’s wind program is toextend that cost effectiveness to convenientsites that are not as windy. This can be doneby making the rotor swept area as long aspossible with out increasing system costs. “We are looking at methods of buildinglarger, stronger blades for turbines using a

hybrid of carbongraphite fibers andfiberglass thatsweep a greater areawithout greatercost,” says PaulVeers, manager ofSandia’s WindEnergy TechnologyDepartment. “Bynext summer weexpect to haveexperimental bladesready for testingwe believe will belighter and stifferthan bladescurrently used in theindustry.”

Sandia has been researching windenergy since the 1970s, but it’s only nowthat the alternative energy source has becomeeconomical enough to find widespread use.Over the past ten years the cost of windenergy has fallen dramatically — to 2.5-4cents a kilowatt-hour in the windiest sites.However, further cost reductions arenecessary in critical subcomponents indesign, manufacturing, and systemintegration, Veers says, to make windturbines cost effective in sites withmodest winds.

Wind farms

Wind farms — fields of wind turbines— can be found in California, SouthwestTexas, Minnesota, the Washington-Oregonborder, Iowa, West Virginia, Pennsylvania,Kansas, and several other states. A newlydeveloped wind farm recently beganoperations at a Public Service Company ofNew Mexico Wind Energy Center near FortSumner, New Mexico. Veers says that in Europe, where windenergy has become particularly popular,turbine manufacturers are starting to producevery large machines. They are frequentlyused for offshore applications where windsare steady and strong.

15


Loweringthe cost of

wind energy

C

Turbines spin at the New Mexico Wind Energy Center, located 170 miles southeast of Albuquerque and 20 miles northeast of FortSumner. The site began producing electricity for Public Service Company of New Mexico (PNM) this fall. The center is the world’sthird-largest wind generation project. (Photo by Norman Johnson courtesy of PNM.)

As the popularity ofwind energy rapidlygrows worldwide,

researchers atSandia NationalLaboratories are

developing ways tolower the cost of

this alternativeenergy and enableturbines to produce

more power.

“However, as machines have grownlarger, issues of scaling and loads have madedetailed engineering even more important,”Veers says. That’s where Sandia comes in —researching how to overcome some of theseissues. Today, the most popular commercialwind turbines have 35-meter blades ontowers that are 65 to 80 meters tall. Theyproduce about 1.5 megawatts each, and theblades are primarily made of fiberglass,although at least one European manufactureruses wood.

Scaling up the blades

Tom Ashwill, who leads the bladedevelopment team, says that the researchblades will be built at sub-scale sizes of nineto ten meters in order for the researchers tocost-effectively grapple with issues such as

fiber material form,degree of carbon/glasshybridization,manufacturability andother traditional issueslike aerodynamics,structural strength, andreliability. Researchersbelieve that qualities ofsuccessful subscaleblades can be scaled upto blades 50 meterslong. These blades

would reside on turbines with 100-metertowers and produce 2 to 5 megawatts each. Sandia is working with bothmanufacturers and designers to bring thefindings of these subscale blade studies upto full-scale application in commercialprototypes. Public-private partnerships arebeing funded through the Department ofEnergy’s Low Wind Speed Turbine program. By next summer the researchers hope tohave six to 12 blades to test at the NationalWind Technology Center near Boulder,Colorado, using its large blade test facilities,and at the Department of Agriculture’sresearch station in Bushland, Texas, usingthree experimental turbines. “We expect over the next few months tomake some real inroads to developing betterblades for turbines,” Ashwill said. “It’s aproject we are all looking forward to.”

Media Contact: Chris [email protected], (505) 844-0948

Technical: Tom [email protected], (505) 845-8457

16


(Photos courtesy of Sandia WindEnergy Department.)

Today, themost popular

commercial windturbines have 35-meter blades on

towers that are 65to 80 meters tall.

Sandia NationalLaboratoriesresearchers wonseven R&D 100Awards this year,plus a “best of thebest” Editor’s Choicerecognition. Thecontest, sponsored

by the Chicago-based trade magazine R&D Magazine,uses technical experts to determine the best newtechnologies. One hundred winners are chosen froman international pool. Sandia won many of the awardsin partnership with private companies, other labs, oruniversities.

Members of the Extreme Ultraviolet LithographyFull-Field Step-Scan System team were singled outfor special recognition at the recent R&D 100 Awardsbanquet in Chicago. The editors described the team’sachievement as “the ‘moon shot’ of technology in thesemiconductor industry.”

The team of more than 50 collaborators fromSandia, other national laboratories and industry wererecognized for advances that will lead to dramaticimprovements in the speed and memory of futurecomputer systems. Researchers created a systemthat can pattern full chip-size areas on silicon waferswith features as small as 50 nanometers.

The R&D 100 Awards were created in 1963. Thesole criterion for winning is “demonstrabletechnological significance compared with competingproducts and technologies.” Here are brief descriptionsof other winning technologies:SnifferStar

An extremely lightweight mobile chemical sensorcreated by seven Sandia researchers and a LockheedMartin staff member, SnifferStarTM mounts on a droneaircraft for remote surveillance of battlefield situationswhere suspect plumes or clouds are present.Acoustic telemetry technology

Acoustic telemetry technology, developed atSandia in cooperation with a Canadian engineeringcompany from Calgary, Alberta, allows real-timemeasurements while drilling. Acoustic telemetrytechnology uses the well-drilling tubing as the data

transmission medium and sound waves as thedata carrier.Low Emissions Atmospheric Metering Separator

The Low Emissions Atmospheric MeteringSeparator (LEAMS) is a family of atmosphericgeothermal separators used to safely contain andclean the atmospheric vented steam of pollutingsolids, liquids, and noxious gasses. This system isdesigned to be environmentally friendly, safe, andeasy to transport and assemble. LEAMS can be usedin geothermal drilling, well testing, and power plantstart-up.Adaptive Optics Phoropter

Two Sandia researchers helped design andintegrate a compact, transportable adaptive opticssystem that determines correction needed for near-sightedness or far-sightedness, astigmatism, andhigh-order aberrations that can interfere with nightvision. The Adaptive Optics Phoropter combinestechnologies from astronomy and micromachining.Mitigating electrical network problems

A fast-response semiconductor device developedunder Sandia direction allows a utility to rapidly convertenergy stored in a DC device into AC power tominimize the negative effects of lightning strikes orequipment failures. The component could become acritical part of inverters, motor controllers, and manyother electronics systems that require medium voltageand high current switches.

Media Contact: Neal [email protected], (505) 845-7078


Sandia researchers earnR&D 100 Awards

Kevin Krenz, an engineer in Sandia’s AdvancedLithography department, inspects components ina first-generation EUV Lithography tool.

SAND 2003-4317P

PRSRT STDU.S. PostagePAID

Albuquerque, NMPermit NO. 232

Media Relations & Communications Dept.MS 0165Sandia National LaboratoriesP.O. Box 5800Albuquerque, NM 87185-0165

“Sandia’s expertise in the areas of impact testingand modeling, material testing, non-continuumaerodynamics, and thermal analysis has been

invaluable to our investigation teams. Thecooperative effort and sharing of

ideas, test methods,and analytical toolshave been beneficial to

both our organizations.”

William ReaddyAssociate Administrator for Space,

National Aeronautics and Space Administration

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