REPORT DOCUMENTATION PAGE Form Approved OMB No. 0704-0188

Public reporting burdoo lor this collection or infoonabon is esbmated to average 1 hour per response, including lhe ~me lor rev~ew1ng instn.Jctions, searchng eJOs~ng da1a sources, gathenng and maintllning the data needed, and complenng and reviewing the colection o1 lnlormanon Send commen1S regardong lhJS burden estimate or any olher aspe<:t or this colleciJon or infoonation. inclucltng suggestions for redudng this bullk!n. to Wash111gton Headquarters Services, Oorectora1e for lnlormanon Operabons anc:l Reports, 1215 Jerterson Davis Highway. SlAte 1204, Arlington, VA 22202-4302, and to !he Office or Management and Budgel Paperwor1t Reduetion Pflllect (0704.0188), washington. DC 20503

1. AGENCY USE ONLY (Leave blank) , 2. REPORT DATE

April 6, 20 0 9

,3. REPORT TYPE AND DATES COVERED Final Progress Report

4. TITLE AND SUBTITLE 5. FUNDING NUMBERS ACQUI SITION OF A COMBINED MECHANO-ELECTRO- CHEMICAL

CHARACTERIZATION EQUIPMENT FOR ADVANCED C/G : FA9550-07 - l - 0558

6. AUTHORS

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) 8. PERFORMING ORGANIZATION Texas Engineering Experiment Station (TEES) REPORT NUMBER 332 Wisenbaker Bldg. MS 3000 College Station, Texas 77843-3000

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSORING/MONITORING AGENCY REPORT NUMBER

A i r Force Office of Scientific Research,

875 N . Randolph Street , AFOSR/NA , Sui te 325, Room 3112' Arlington, VA 22203

11. SUPPLEMENTARY NOTES

12a. DISTRIBUTION/AVAILABILITY STATEMENT 12b. DISTRIBUTION CODE

13. ABSTRACT (Maximum 200 words) The acquisition of the custom-designed Nanonics Multiview 400 Combined microRaman, Scanning Probe Microscope (SPM), and Nanoindenter system equipment will a llow us to bridge t he divide between the fundamentals of materials science, chemist ry, physics, biology, nanomanufacturing , and engineering , and i t serves as a unique training plat form for students f rom science and engineering. Such combined system integration permits correlation of SPM t opography of a s ample surface with microRaman spectra, and it enabl es the characterization of local mechanical, chemical and electrical properties in-s i tu and simult aneously in active polymers and nanocomposites. Due to the custom-built nature of the equipment and the fact that receipt o f the DURrP funds were delayed, the equipment was finally deli vered on January 2009. I nstallation took place within a month, and was completed by e nd of February 2009 . Two researchers in PI Ounaies• group were trained on most of t he functions . So far, the focus has ~een on getting famil iar wi th the SPM, nanoinde.ntation and Raman s pectroscopy func tions. In the next few months , the focus wil l shift to the ' unique features s uch as the combined Raman and nano indentation and the SPM/Raman combinat i on .

14. SUBJECT TERMS 15. NUMBER OF PAGES 9

Nanoindentation; Raman spectroscopy; Atomic force microscopy; nanocomposites; Characterization. 16. PRICE CODE

17. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION 19. SECURITY CLASSIFICATION 20. LIMITATION OF ABSTRACT OF REPORT OF THIS PAGE OF ABSTRACT SAR ( same as report}

UNCLASSIFIED UNCLASSIFIED UNCLASSIFIED

NSN 7540-01-280-5500 Computer Generated STANDARD FORM 298 (Rev 2-89) Prescribed by ANSI Std 239-18 298-102

A

AFRL-OSR-VA-TR-2012-0476

RESEARCH AND EDUCATION

1

ACQUISITIONOFACOMBINEDMECHANO‐ELECTRO‐CHEMICALCHARACTERIZATIONEQUIPMENTFORADVANCEDNANOCOMPOSITES

RESEARCHANDEDUCATION

DefenseUniversityResearchInstrumentationProgram2007

AirForceOfficeofScientificResearch

ProgramManager:Dr.LesLee

Program:MechanicsofMultifunctionalMaterialsandMicrosystems

Investigators:

ZoubeidaOunaies,AerospaceEngineering,TexasA&MUniversityHong(Helen)Liang,MechanicalEngineering,TexasA&MUniversityUsersandCollaborators:

RamananKrishnamoorti,ChemicalEngineering,UniversityofHoustonXinghangZhang,MechanicalEngineering,TexasA&MUniversityHaiyanWang,ElectricalEngineering,TexasA&MUniversityMiladinRadovic,MechanicalEngineering,TexasA&MUniversityRichardVaia,AFRL/MLBP

2

ABSTRACT

Wehaveacquiredacustom‐designedNanonicsMultiview400CombinedmicroRaman,ScanningProbeMicroscope(SPM),andNanoindentersystem.Suchcombinedsystemintegrationpermitscorrelationof

SPMtopographyofasamplesurfacewithmicroRamanspectra.TheNanonicsSPM/NSOMcomponentgeneratessurfacemorphologyimageswhileRamancomponentscanmeasureelectricalpropertiesandchemicalsignatures.ThepresenceoftheNanoindenterallowssimultaneousdetectionofRamanpeaks

under stress. Thebroadgoal is topermit characterizationof localmechanical, chemicalandelectricalpropertiesin‐situandsimultaneouslyinactivepolymersandnanocomposites.Theproposedequipmentwill greatly impact an ongoing AFOSR project on active nanocomposites, as well as ongoing and

proposed DoD and NSF projects lead by the PIs. The capabilities of the custom‐designed Nanonicsexpandtonanoscalemechanical,electrical,andchemicalpropertiesofmetallicandceramicthin filmsand coatings, andMEMS andNEMS devices, extending its impact to a variety of ongoing and future

collaborationsandresearchprojects.Thecombinationofmicron‐scaleandnano‐scaletechniquesintheproposedequipmentmakesituniquelycapableofbridgingthegapbetweeninterfacialinteractionsandmacroscalepropertiesinadvancedmaterialsingeneralandnanostructuredmaterialsinparticular.The

surfacemorphologicalinformation,internalstress,andelectricalpropertiesofsuchmaterialshavebeenstudiedseparatelyandthestructure‐propertyisyettoberelatedintrinsically.Havingsuchasystemwillenable us to investigate the interfacial forces between components and understand the effects of

molecularstructureandinclusiondistributiononnanocomposites.Thesimultaneouscapabilitiesofthecustom‐designed equipment are unique and will complement and expand our research and currentmaterialscharacterizationinfrastructure,specificallyintheareaofmultifunctionalmaterials.

Due to the custom‐built nature of the equipment and the fact that receipt of theDURIP fundsweredelayed, theequipmentwas finally shipped toour laboratory in January 2009. The complexity of theequipmentrequiredthatanengineerfromNanonicstravelstoourlaboratorytoinstallitandtrainusers.

Byendof February, theequipmentwasoperational and two researcherswere trainedonmostof itsfunctions.The followingmonths, the focuswason testingandgetting familiarwitheachof the threeoperations:TheScanningprobemicroscope,thenanoindentation,andtheRamanspectroscopy.Inthe

nextstep,presentlyandforthenextmonth,theresearchersaretrainingonusingtheuniquefeaturessuchasthecombinedRamanandnanoindentation,andSPMandRaman.

3

1. DescriptionoftheAcquiredEquipment.

Figure1 shows theequipment inour laboratory.Weweregivenanewspace in thebasementofourmain building to accommodate the equipment and ensure that no ambient vibrationswill disturb its

operation.

Figure1.Installedequipment.

Thebasicideaofthissystemistocombinethenanoindentationandnanoscratchwithscanningimaging

analysis. TheSPM imagesandmeasures surfacesonananometer length scalewithina few layersofatoms.Withasharptip,withinarangeof3‐50nmradiusofcurvature,attachedonaflexiblecantilever,interactionsbetweenthetipandmaterialsurfacescanbepreciselydetected.Tofurthercustomizethe

equipment to our needs, the Nanonics MultiView 400™ system can be directly integrated into theRenishawRMSeriesRamanMicroscopetogether,asillustratedinFigure2.Thesemicroscopesemploytheuprightmicroscopeconfiguration,andtheNanonicsMultiView400™isreadilyplacedonthesample

stageofsuchamicroscope.TheNano‐indentation/SPMsystemisauniqueinstrumentforcharacterizingthe elastic, plastic, stress‐strain, hardness, creep, fracture, residual stresses and other mechanicalpropertiesofcoatings,thinfilms,interface,bulkmaterialsandthenearsurfaceregionofmaterials.The

microRaman system is capable of measuring spectra from both solid and liquid samples. Using thissystem,itispossibletoinvestigatecrystalstructure,orientation,compositionandstress.Itisnotedthatallother systemswehave investigatedcombiningAFMandRamanperformanAFMscanoraRaman

scan separately. The custom‐designed system we purchased is the Nanonics‐Renishaw combination,whichprovidessimultaneousandon‐linedatafrombothmodalities.Thisenormousadvantageresolves

critical problems in Raman such as intensity comparisons in Raman images and provides for newavenues of improved resolution and unique characterization. The Nanonics patented cantileveredopticalfibersareheldbetweenthemicroscopelensandthesamplewithoutobstructinganyaspectof

4

the far‐field optics. The tip in these fibers is exposed and illuminated by the lens of themicroscope,allowing theuser toview theexact regionwhere theSPMandRaman information isbeing collected.

Withthecombinedsystem,onecannowrecord,inparallelwithRaman,awidevarietyofscannedprobeimagingmodalities.Forexample, inMEMS,whilethesilicon(Si)Ramanpeakofamicrocircuit isbeingmonitored to detect stress in the silicon, the Raman spectroscopist can simultaneouslymeasure the

circuit'smicro‐topographywithAFM,and itsNSOMreflectivityor itselectricalproperties, suchas thedopantconcentration.Inaddition,Nanonicsprovidessoftwarethatcandisplayalltheseimagesatoncefordirectandsimultaneouscomparisonandanalysis

2. CurrentStatus.

TheactualexperimentationonandtestingoftheNanonicsunitstartedrightafterthe installationand

trainingwhichtookplace inFebruary2009.The initial installationandtraining lastedaweekandwasthenfollowedbyacoupleofonlinetrainingsessionssupportedbytheNanonicscompany.Theseonlinetrainingsessionsarestillongoingfromtimebytime,whenevertheneedarises.

Given the fact that the Nanonics Multiview 400 is composed of three different characterization

techniques namely: scanning probe microscopy (SPM, or atomic force microscopy (AFM)),Nanoindentation and Raman Spectroscopy. In addition, besides having the capability of runningindividualscansforeachtechnique,thereisalsothecapabilitytoruncombinedintegratedexperiments

(AFM‐Raman) andNanoindentation‐Raman. The following report briefly explains the experimentationprocedurealongwithourrecentlyobtainedresultssofarfromtheunitineachofthecategories:

2.1‐ScanningProbeMicroscopy(SPM)experiments

InrunninganSPMexperiment,thefirststepismountingtheNanonicSPMtiponthetipmount,usingapairoftweezers.AfterwardsthetipmountisplacedontheNanonichead(Figure3).

5

Figure3.(a)AFMopticalfiberprobetip(b)Nanonicheadcontainedoftwoplanes.Theupperplaneiswherethetipmountisplaced.Thelowerplaneisusedtomountthespecimen.

TheNanonicsMultiview400unitbenefitsfromaLaserdeflectionbeamfeedbackenablinganaccurate

controlandonlineacquisitionoftip’srelativepositionbasedonNanonics’headcoordinatesystem.TheprocessinvolvesfocusingtheLaserbeamontoaspecialplaceoftheprobetip,byaimsofasmallmirror,andreflecting itonto thePositionSensitiveDetector (PSD)asshown inFigure4.Since,at the timeof

AFMexperiment,theforceappliedbytheinteractionoftheprobewiththesamplecausestheprobetobend,thelaserbeamisdeflectedfromitsoriginalpositionwhichwillbedetectedbythePSDmonitor.

Figure4.(a)asideviewdiagramoffeedbacklaserandPSDmonitor(b)Animageoftherightpositionofthelaserontheprobetip.

NanonicsMultiview400enablesustorunAFMscansintwodifferentmodes:1‐Contactmode,and2‐IntermittentorTappingmode.InContactmode,thetipisbroughtintocontactwiththesamplefollowedbyscanningauser‐definedportionofthesamples’surfaceinanydesireddirection.IntheIntermittent

mode, the probe tip would be oscillating in its resonant frequency and therefore the AFM scan isperformedbyaspecificnumberoftappingmotionsofthetippersecondonthesurface. Thecontactmode issimplerandmoreuser‐friendlybutsincethetip is incompletecontactwiththesampleatall

times, itmaycausesomedamage to thesampleor to the tip.On theotherhand, in the intermittentmode,sincethetipisnotincontactthroughmostofitstappingcycle,thesurfacedamageislesslikelyandalsolongerdurabilityofthetipisexpected.Figure5showsoneofourdesktopviewwhileanAFM

experimentisrunning.Ontheleftsideofthepicturealivevideoofthescanningareaisshown.Ontherightside,thereisaheightversusdistancediagram(inblue)besidestheerrorsignal(inred)helpingustogetthebestAFMimagebycontrollingthenoiseanderrorsignal.

6

Figure5.AdesktopviewofanongoingAFMexperiment

Figure6‐(a)showsanAFMimageofapieceofSi‐SiO2grid.Whiteareasarelithographedsiliconedioxidesquares on a silicone substance. Figure 6‐(b) shows our AFM experiment on a piece of Polyurethane

(PUR) sample.As it couldbe seen in thepicture,AFMallowedus to figureout theorientationof thecrystallineregionsversusamorphousonesinthePURsample.

Figure6.AFMimageof(a)aSiliconechip(b)Polyurethane

2.2‐Nanoindentationexperiments

The mechanism of the nanoindentation in Nanonics Mutiview 400 is quite similar to the AFMexperiments.ThesameLaser feedbacksystemwouldbeused fordataacquisitionbut insteadofAFM

probe tip, nanoindentation tips are used. Nanoindentation is performed only in intermittent mode.After doing preliminary steps including focusing laser beam, adjusting PSD monitor and setting theresonantfrequencyofthetip,thecalibrationheight‐forcegraphshouldbegenerated.Asapphireglass

with known properties is used for this purpose. The tip would land on sapphire glass and, sincemechanicalpropertiesofthetipareknown(suchas itsspringconstant),theforceofthetipwouldbecalibratedfortheactualexperiment.Finallythenanoindentationwouldberunbyreplacingthesapphire

glasswiththesampleinquestion.Figure7showstheforce‐heightdiagramloopafternanoindentationofapolyimidesample.SubsequentlytheunitprovidesuswiththeopportunitytocaptureanAFMimage

7

of thenanoindentedarea.Figure8‐(a) showsanAFM imageofananoindentedareausingadiamondnanoindentationtip.

Figure7.ForceHeightdiagramofPolyimidesample

Figure8(a)Nanoindentationusingadiamondtip(b)AnarrayofNanoindentedpoints

Theunit alsoallows formultiple consecutivenanoindentationexperiment inwhichanarrayofpointscouldbeindentedanddesiredmechanicalpropertiescouldbemeasuredbytakinganaverageofthem.Figure 8‐(b) shows an AFM image of an array of Nanoindented points after running a multiple

Nanoindentationtest.TherawdataofthisNanoindentationtestisshowninFigure9.

8

Figure9.MultipleNanoindentedloopsofanarrayofnanoindentedpoints

Itisworthnotingthatthenanoindentationtoolcouldbeusedtoscratchsamplesifwritingormarking

onthesurfaceofthesampleisdesired.

2.3‐RamanSpectroscopy

NanonicsMultiview400isequippedwithagreenLaserwith532nmwavelengthforRamanspectroscopymeasurements.Theunit includesanopticalfiberconnectionbetweenthelasersourceandtheopticalmicroscopetodirectthe laserbeamontotheNanonicshead. A50xobjective isusedtobringagood

focusofthebeamonthesample.ThereflectedlaserbeamfromthesamplewouldbetransferredtotheRamanspectrometer,usinganotheropticalfiber,usedforanalyzingtheresultingRamanSpectra.Figure10 shows the Raman spectra of a silicone sample. The stoke peak of the silicone could be seen at a

wavelengthofaround547nmwhileasmallanti‐stokepeakisrightontheothersideofthelaserpeakbutwithweakerintensity.

Figure10.RamanSpectroscopyofasiliconesample

‐800‐700‐600‐500‐400‐300‐200‐100

0100200

‐4000‐3500‐3000‐2500‐2000‐1500‐1000‐5000

Monitor(mVolts)

Height(nm)

0

50

100

150

200

250

510 520 530 540 550 560 570wavelength(nm)

Intensity

(ArbitraryValue)

RamanpeakofLaser

SiliconeAnti‐stoke

Siliconestoke

9

3.FutureFocusontheSpecialFeatures

The unit is also capable of running combined microRaman/AFM experiments which gives a superiorcorrelationofsurfacetopographyofasamplewithitsRamanspectra.RamanSpectroscopysoftwareisalso equippedwith a visual contrast feature giving the operator the opportunity to superimpose theRAMAN imageonto the topographicAFM image. Figure11 showsa3D collage imageof this feature,whichwehaveattempted.Masteringofthisuniquecapabilityisongoing,withcontinuedsupportfromNanonics engineers. Our goal is to use this capability to further inform our research in activenanocomposites.ThecouplingoftheSPM,nanoindentationandmicroRamanwillenablefundamentalstudiesinto;1)investigatinginterfacialphenomenathatincludeadhesionandphasetransformation,2)quantifying extremely localized and interfacial stress, 3) measuring the force magnitudes of theenergetic electrons on particle surfaces when interacting to form different types of bonding, and 4)investigating particle interactions which is the most important and fundamental question in theunderstandingnanocompositeinterfacesandmechanics.Theunderstandinglistedherewillassistinourongoingdevelopmentofadvancedmaterials,suchasnanocompositesandactivematerials.

Figure11.MicroRaman/AFMcollageofSi‐SiO2gridsample