NPL Final cover 180610€¦ · ).crystals with larger diameters up to 40 mm have been grown to meet...

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Transcript of NPL Final cover 180610€¦ · ).crystals with larger diameters up to 40 mm have been grown to meet...

Page 1: NPL Final cover 180610€¦ · ).crystals with larger diameters up to 40 mm have been grown to meet the device applications by a low thermal gradient Czochralski technique. Lithium
Page 2: NPL Final cover 180610€¦ · ).crystals with larger diameters up to 40 mm have been grown to meet the device applications by a low thermal gradient Czochralski technique. Lithium

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inkFkksZ ds vfHky{k.ku ds vUrxZr la?kVu vkSj lajpuk dh mu fo”ks’krkvksa dk o.kZu fd;k tkrk gS tksfdlh fof”k’V rS;kjh] xq.k/keksZa dk v/;;u vkSj@;k inkFkZ ds iqujksRiknu ds fy, i;kZIr gksrs gSa A inkFkksZa dsxq.k/keksZa ds fy, mRrjnk;h muds vk/kkjHkwr esa mudk la?kVu vkSj “kq)rk] fØLVykbu volajpuk vkSj ijek.kq Lrjij volajpuk dh laiw.kZrk “kkfey gksrh gS A ,u ih ,y esa inkFkZ ds fo”ys’k.k dh ;ksX;rk dk egRo] blds vk;kstuds le; gh le> fy;k x;k Fkk A orZeku esa ,u ih ,y esa inkFkksZa ds vfHky{k ds fy, vR;k/kqfud vkSj uohurefHkUu & fHkUu lqfo/kk,sa miyC/k gSa A buesa ,Dl&js fo”ys”k.k ¼ ,Dl vkj Mh] ,Dl vkj ,Q] ,p vkj & ,Dl vkjMh ½] bysDVªªkWu ekbØksLdksih ¼ ,l bZ ,e] Vh bZ ,e] bZ Mh ,Dl] ,p vkj&Vh bZ ,e ½] vk;u ekbØksLdksih ¼ Vhvks ,Q&,l vkbZ ,e ,l] vkbZ lh ih ,e ,l½] vkf.od LisDVªªksLdksih ¼ , , ,l ½] Ádk”kh; LisDVªªksLdksih¼ ;w oh & oh vkbZ ,l] ih ,y ½] jklk;fud fo”ys’k.k ¼ th lh & bZ lh Mh] th lh & Vh lh Mh@,Q vkbZ Mh],p ih &,y lh ,e ,l ½] rFkk pqEcdh; ekiu ¼ bZ ih vkj ½ “kkfey gksrs gSa A

inkFkZ vfHky{k.ku foHkkx }kjk ,u ih ,y esa fodflr fd, tk jgs vusd inkFkksZa tSls fFku fQYe] uSuksinkFkZ ftuesa uSuks V;wCl] uSuks jkM~l] uSuks ok;lZ] bathfu;jh vuqÁ;ksxksa ds fy, daiksftV inkFkZ] fMokbl Ýsfczds”kuds fy, bysDVªªkWfud inkFkZ vkfn “kkfey gSa] ds vfHky{k.ku ls lacaf/kr dk;Z fd;k tk jgk gS A bl foHkkx }kjkÁ;ksx”kkyk dh vuqla/kku ;kstuk dks /;ku esa j[krs gq,] ,sls bu fHkUu & fHkUu inkFkksZa ds fodkl dk dk;Z Hkh fd;ktk jgk gS tks fd ÁkS|ksfxdh; :i ls egRoiw.kZ gS ] rFkk muds fo”ys’k.k vkSj fodkl ds lkFk lkFk] fodkl ra=dh ÁfØ;k fu;a=.k ds b’Vrehdj.k ds fy, varr% vfHky{k.ku fd;k tkrk gS A vHkh gky gh esa] bl foHkkx }kjkX;kjgoha iapo’khZ; ;kstuk ds nkSjku ¼ bZ,Q Qh½ inkFkZ ekfidh vkSj jlk;u ekfidh dk;ZØe ds vUrxZr ykus dsfy, dne mBk, tk jgs gSa A

1- inkFkZ ekfidh vkSj jlk;u “kkL= esa ekfidh dh ubZ xfrfof/k ds vUrxZr] ,u ih ,y }kjk vius fed(MiC) usVodZ lk>snkjksa ds lkFk jklk;fud ekiu esa vuqjs[k.kh;rk Ánku djus ds fy, /;ku dsfUærfd;k tk jgk gS ftldk y{; {kerk fuekZ.k] fofHkUu {ks=ksa esa vuqla/kku vkSj fodkl djus] vUrjkZ’Vªªªh;Á;ksfxd vkSj egRoiw.kZ rqyukRedrkvksa esa Hkkx ysus ds fy, djuk gS vkSj blesa çekf.kr lanHkZ inkFkksZa ¼lh

vkj ,e½ dks rS;kj djuk vkSj laforj.k djuk Hkh “kkfey gS A ,u ih ,y ds vkarfjd vuqla/kku dk;Z]

ljdkjh ,tsafl;ksa vkSj laLFkkuksa dh fofHkUu inkFkZ vfHky{k.k vko”;drkvksa tSls fnYyh ty cksMZ }kjkikuh ds “kks/ku ds fy, ç;ksx fd, tk jgs ,Y;qfefu;e DyksjkbM vkSj ,Y;qfeuk QSfjd xzsM&2] Hkkjr ds

fuokZpu vk;ksx dh vksj ls pquko mís”;ksa ds vfeV L;kgh ¼ baMsfycy bad ½ vfrfof”k’V O;fDr;ksa dh

lqj{kk ds fy, xSl feJ.k vfHky{k.ku] xzsQkbV] DokV~Zt] flYoj dkUVsDV~l uewuksa vkfn esa /kkfRodv”kq}rkvksa ls lacaf/kr dqN egRoiw.kZ lsok,sa çnku dh xbZ gSa A

2- mPp ckjEckjrk {ks=ksa esa ekbØksoso vo”kks’k.k ds fy, e`nq /kkfRod pqacd laHkkfor inkFkZ gS A bl lanHkZ esauSuks eSxusfVd dksckYV vk;ju (Co Fe2 ) uSuks feJ/kkrq dks jklk;fud fçislhihVs”ku ekxZ ls la”ysf”krfd;k x;k gs rFkk Ku cSaM (12-4 & 18 xsxk gV~tZ ) esa ekbØksoso vo”kks’k.k ds fy, fØLVsykbu vkdkj]v.kq vkdj] pqacdh;dj.k rFkk pkydrk ds laca/k esa fo”ys’k.k fd;k x;k A

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3- v/kZ Lopkfyr vkSj vk/kqfudhd`r bu&gkml fodflr ØkspkyLdh (Czochralski ) 40 feyhehVj ds cM++sO;kl rd ds fyfFk;e fuvkscsV (,y fØLVy iqyj ds lkFk vkj ,Q rkiu Á.kkyh dh lQyrkiwoZdLFkkiuk ds ckn] fuEurkih; xzsfM,UV ØkspkyLdh rduhd }kjk miLdj vuqç;ksxksa dks iwjk djus ds fy,vkbZ ,u ch vks

3) fØLVyksa dks fodflr fd;k x;k gS A csgrj ;kaf=dh vkSj jklk;fud fLFkjrk vkSj foLr`r

ikjnf”kZrk ds lkFk&lkFk fof”k’V bysDVªªks vkfIVdy ¼bZ&vks½] ,dkfLVd vkfIVd ¼,&vks½] QksVksbykfLVd]ihtks&bysfDVªd rFkk vjs[kh; vkWfIVdy ¼ ,u ,y vks ½ xq.k/keksZa ds dkj.k fyfFk;e fuvkscsVvkWIVksbysfDVªªksfuDl ds fy, lcls vkd’kZd lkefxz;ksa esa vkrk gS A 23 vkdZ ,l dh ,Q McY;w ,p ,eeku ds lkFk rhoz vkSj ,dy mPpre fMÝsD”ku oØrk }kjk , ,l&xzksu fØLVy dh “kkunkj xq.koÙkk dksn”kkZrk gS ftlls njkjsa vkSj vkarfjd voljpukRed xzsu lhek,aa fn[kkbZ ugha nsrh gSA

4- xzkQsu vkDlkbM usuks”khV~l ¼,d ?kksy vk/kkfjr ,dy pj.k fof/k tks xzkQsu vkDlkbM uSuks”khV~l esaflYoj uSuksikfVZdYl dks varfuZfgr djrh gS ½ esa flYoj uSuksikfVZdYl dks vUrfuZfgr djds xzkQsu /kkrquSuksgkbZfczM vlsEcfy;ksa dks la”ysf’kr fd;k x;k gS A bl izdkj xzkQsu “khV~l ds vkIVks bysfDVªdxq.k/keksZa dks eSXuhV;wM ds vusd vkMZjksa esa V;wu fd;k tk ldrk gS ftlls os laHkkfor ykspiw.kZ vkSjikjn”khZ lsehdaMDVjksa vFkok v/kZ /kkrqvksa ds fy, laHkkfor rkSj ij mi;ksxh gks ldrs gSa A

5- ,l vkbZ @Vh ,e ¼ Vªkaft”ku esVy ½ ,l vkbZ flLVe @ ,l vkbZ flLVe ¼oh @ ,l vkbZ] ,Q bZ @,l vkbZ rFkk lh vks @ ,l vkbZ ½ ds laca/k esa vius fiNys dk;ksZa dks tkjh j[krs gq,] ,d vU; Vªkaft”kuesVy vFkkZr~ ,e ,u dks vekjQl flfydkWu ¼ , ,l vkbZ ds lkFk fefJr djus dks pquk x;k gS D;ksafdbl /kkrq ij “kk;n gh dksbZ v/;;u fd;k x;k gks @ ,l vkbZ flLVe mPp & ÅtkZ jsthesu esa vkrkgS A ;gkW¡ rd fd ,l bZ & mPpre lhek eku ds laca/k esa dksbZ tkudkjh Hkh miyC/k ugha gS A feJ.knj ds :i esa] bl dk;Z dks ,l ,p vkbZ & Ásfjr baVjQsl feJ.k dh ek=kRedrk dks fu/kkZfjr fd, tkusdk iz;kl gS ftlds ifj.kkeLo:ir% rkih; Likbd ekWMy ds ÝseodZ esa bl Áo`fÙk dks le>k tk ldsvkSj nwljk bl ckr dh tk¡p djuk dh dejs ds rkieku ij dksbZ flfylkbMs”ku rks ugha gqvk gS A

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MAMAMAMAMATERIALS CHARATERIALS CHARATERIALS CHARATERIALS CHARATERIALS CHARACTERIZACTERIZACTERIZACTERIZACTERIZATIONTIONTIONTIONTION

Characterization of materials describes those features of the composition and structure (including defects)of a material, that are significant for a particular preparation, study of properties and/or suffice for the reproductionof the material. The basic characterization of materials responsible for their properties are the composition andpurity, crystalline structure and perfection of structure at atomic level. The importance of the capability formaterial analysis at NPL was realized even at the time of its planning. Presently NPL has wide variety of state-of-the art sophisticated facilities for characterization of materials. These include X-ray analysis( XRD, XRF,HR-XRD), electron microscopy ( SEM, TEM, EDX, HR-TEM), ion microscopy (TOF-SIMS, ICPMS),atomic spectroscopy(AAS), optical spectroscopy (UV-VIS, PL), chemical analysis ( GC-ECD, GC-TCD/FID, HP-LCMS) and magnetic measurements (EPR).

Material characterization division has been characterizing various materials that are being developed atNPL, like thin films, nano materials including nano tubes, nano rods, nano wires, composite materials forengineering applications, electronic materials for device fabrication etc. The division is also working ondevelopment of different materials which are technologically important, their synthesis and growth and finallycharacterizing them for optimization in process control of the growth mechanism, keeping in view the researchplan of the laboratory. In the recent past, the division has taken up a new programme under the eleventh fiveyear plan (EFP), Material Metrology and Metrology in Chemistry. Under this programme the implementationof Quality system as per ISO 17025 is being pursued in the division and all the necessary steps are being takento bring this division under ‘Advanced Metrology’ programme of NPL.1. Under the new activity of Material Metrology and Metrology in Chemistry, focus has been given for

providing traceability in chemical measurements by NPL with its MiC network partners by buildingcapacity, doing R&D in various areas, participating in international pilot & key comparisons and includespreparation & dissemination of certified reference materials (CRMs). The chemical characterizationneeds of NPL in-house research work, government agencies and institutions for characterization of avariety of materials viz. poly aluminum chloride and Alumina Ferric Grade-II used for treatment ofwater by Delhi Jal Board; indelible ink for election purpose from Election Commission of India; gasmixtures characterization for VVIP security, metal impurities in graphite, quartz, silver contacts samplesetc. are some of the important services rendered during this period.

2. Soft metallic magnets are potential materials for microwave absorption in high frequency region. In thiscontext nano-magnetic cobalt iron (CoFe2) nano-alloy have been synthesized by chemicalcoprecipitation route and studied for microwave absorption in the Ku band (12.4-18 GHz) region.Prepared material was analyzed for crystalline phase, crystallite size, particle size, magnetization andconductivity measurement relevance to microwave absorption.

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3. After successful installation of RF heating system with semi-automated and modernized in-housedeveloped Czochralski crystal puller, good quality Lithium niobate (LiNbO3).crystals with largerdiameters up to 40 mm have been grown to meet the device applications by a low thermal gradientCzochralski technique. Lithium niobate is one of the most attractive materials for optoelectronics dueto its unique electro-optical (E-O), Acousto-Optic (A-O), photoelastic, piezo-electric and nonlinearoptical (NLO) properties combined with good mechanical and chemical stability and wide transparency.The sharp and single peak diffraction curve having FWHM value of 23 arc s depicts the excellentquality of the as-grown crystal revealing the absence of cracks and internal structural grain boundaries.

4. Graphene-metal nanohybrid assemblies have been synthesized by embeding the silver nanoparticlesinto graphene oxide nanosheets ( a solution-based single step method that embeds the silver nanoparticlesinto graphene oxide nanosheets) . The opto-electronic properties of the graphene sheets can thus betuned over several orders of magnitude, making them potentially useful for flexible and transparentsemiconductors or semi-metals.

5. In continuation to our previous work on Si/TM(transition metal)/Si systems (V/Si, Fe/Si and Co/Si)the mixing of another transition metal, Mn, with amorphous silicon (a-Si). is chosen as hardly anydetailed study has been done on this metal/Si system in high-energy regime. Even the information aboutits Se-threshold value is not available. This work is an attempt to quantify SHI-induced interface mixingin terms of mixing rate and thereby understand this phenomenon in the framework of thermal spikemodel and secondly, to check if some silicidation has taken place at room temperature.

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Chemical Metrology SectionMetrology in Chemistry (MiC) and Certified

Reference Material (CRM) are major activities of thechemical metrology section under the ‘Advances inMetrology’ CSIR Network project. Herein, focushas been given for providing traceability in chemicalmeasurements by NPL with its MiC network partnersby building capacity, doing R&D in various areas,participating in international pilot & key comparisonsand includes preparation & dissemination of certifiedreference materials (CRMs). The preparation &dissemination of CRM or Bhartiya Nirdeshak Dravya(BND) as calibration standards; maintain theirinternational comparability and hence to provide SItraceability in chemical measurements are envisagedfor various user levels. This section during this periodhad also catered to the chemical characterizationneeds of NPL in-house research work, governmentagencies and institutions for characterization of avariety of materials viz. poly aluminum chloride andAlumina Ferric Grade-II used for treatment of waterby Delhi Jal Board; indelible ink for election purposefrom Election Commission of India; gas mixturescharacterization for VVIP security, metal impuritiesin graphite, quartz, silver contacts samples etc. duringthis period. A chemical process for ZnO nano particlesynthesis has been developed for getting desiredmorphology. The ZnO powder has been seen toremove arsenic and chromium from potable water.Two sponsored projects are being implemented forMinistry of Environment & Forests nationalcommunication (NATCOM-SNC) for GHG QA/QCand traceability. NABL sponsored proficiency testing(PT) project in chemical discipline (code PT-44) forthe NABL accredited laboratories has beencompleted for Phase-I and Phase-II is underway.Under APN sponsored aerosols & health project andunder ISRO-GBP special observational programme(ICARB) in Delhi and data analysis under such field

campaign studies by the group have been done forsuspended particulate matter (SPM) and its chemicalcomposition apart from aerosol size and massdistribution by Anderson and quartz crystalmicrobalance (QCM). Trace gas & aerosolmeasurements from residue burning have been carriedout in Patiala district of Punjab in collaboration ofThapar University.

Participated in international inter-comparisonviz. CCQM-K51 (CO in nitrogen), APMP.QM-K24/ P-12 key comparison for Cadmium content inRice powder coordinated and conducted by NMISASouth Africa, AASD Govt. Laboratory Hong Kong,and KRISS Korea respectively. These inter-comparison participations had shown our capabilityin gas & inorganic analysis area. An importantachievement of Metrology in Chemistry (MiC)programme during February 2009, was theestablishment of a Primary Standard ReferencePhotometer (SRP) at RASD NPL procured fromNIST-USA, to calibrate air-monitoring instrumentsused to measure the ozone content of ambient airand which is going to help in quality assurances andtraceability of the ozone measurement data generatedin the country, comparable to international level. Sixnew CRMs of mono [BND-305.01 Arsenic, BND-401.04 Chromium, BND-405.01 Chromium, BND-2101.01 Potassium] and multi elemental [BND-

Fig. 5.1: Release of CRMs by Dr Robert Kaarls

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Fig. 5.3: (Refelection + transmission loss) andabsortion loss vs. microwave frequency

2401.01 Copper, Iron & Zinc and BND-2305.01Lead, Cadmium & Nickel] solutions have beenreleased on 30th May 2008 at NPL in MiCinternational workshop, by Dr. Robert Kaarls,president CCQM & secretary CIPM.

EPR & IR Spectroscopy SectionThe use of microwave absorption materials

has attracted great interest due to rapid increases ofelectromagnetic interference (EMI) pollution bycommunication devices like mobile phones, local areanetwork, radar systems etc. For the significantabsorption of unwanted electromagnetic waves thematerials are essentially required to have the specificshape and size distribution of particles is veryimportant for the electromagnetic wave absorption.Particles with size less than the skin-depth (~1μm foriron in the 1–20 GHz range) are the best to increaseeffective incidence to EM wave absorbers bysuppressing the eddy current phenomenon. Largesurface to volume ratio of these conducting andmagnetic materials makes them very important. Softmetallic magnets are potential materials for microwaveabsorption in high frequency region. In this contextnano-magnetic cobalt iron (CoFe2) nano-alloy havebeen synthesized by chemical coprecipitation routeand studied for microwave absorption in the Ku band(12.4-18 GHz) region. Prepared material wasanalyzed for crystalline phase, crystallite size, particle

size, magnetization and conductivity measurementrelevance to microwave absorption. In a nano phasematerial particle size, shape and their distributionalways plays a crucial role in modeling its physicalproperties. Figure 5.2 shows the electron micrographof the sample.

Micrograph shows the average particles sizein the range of 20-100nm and majority of nano- alloyparticles are spherical in shape. However, fewindividual particles seem to be made up of more thenone small particles joined from the surface. Themicrowave absorption studies of material have beendone using vector network analyzer. Electromagneticparameters like dielectric constant, magneticpermeability and reflection, transmission andabsorption losses by the sample were obtained for1.75mm thick sheet. Results reveal the absorptionloss of ~65 dB with reflectance loss less then 1dBand almost zero transmittance in the measuredfrequency range.

Fig.5.2: SEM micrograph of CoFe2 nano-alloy

Figure 5.3 shows the reflection andabsorption loss of incident microwave and the valuesof dielectric constant and magnetic permeability ofthe material. An absorption loss of 65 dB was reachedin the entire frequency range with an absorberthickness of 1.75 mm. The high-frequencypermeability of metallic magnetic materials decreasedue to the eddy current phenomenon induced by EMwave interference. These materials exhibit improved

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microwave absorption properties because of theirproper EM matching between the dielectric loss andthe magnetic loss.

Size dependent nano crystalline cobalt ferrite(CoFe2O4) particles have been synthesized by co-precipitation and investigated in details. The effect ofreducing the particle size on physical properties likecrystalline phase, crystallite size, lattice strain, IRabsorption, thermo magnetic measurements andmagnetization parameter are studied. Structuralparameters in relevance to shape and size of nanoparticles are discussed. The crystalline phase of cobaltferrite remains stable down to 5 nm. Size dependentmagnetization and the effect of surface area arepresented. Characterization of samples has beendone using XRD/TEM/FTIR/VSM and TGAtechniques. The XRD, TEM and VSM results showsa decrease in crystalline properties, particle size andmagnetization on increasing the nucleation rate byincreasing the pH of the precipitating solution. Thusthis work will have potential application in makingferrofluid and nano magnetic based devices.

Crystal Growth and CrystallographySection,Growth and characterization of strategic andtechnologically important nonlinear optical(NLO) crystals and development of CRMs

Due to high-speed and ease of productionof photons (light), the area of photonics has becomean active field of research in view of modern society’sdemand for improved telecommunications, dataretrieving, storage, processing and transmission. Thedesign of devices that utilize photons instead ofelectrons in the transmission of information hascreated a need for new materials with unique opticalproperties. Hence, it will be useful to synthesize newNLO materials and study their structural, physical,

thermal and optical properties. It is also equallyimportant to enhance the NLO properties of theknown materials by either the incorporation offunctional groups or dopants, for tailor madeapplications. Because of the complexity, integration,miniaturization of the modern technologies, thestructural perfection and purity becomes verystringent. In view of the above facts, growth andcharacterization of various organic, semi-organic anda few inorganic crystals like lithium niobate, bismuthsilicon oxide, lithium fluoride crystals have beencarried out.

Some of the important R&D achievements(which were published in 37 SCI journals) madeduring this year are as follows: (i) Growth by SRmethod and characterization of bis(thiourea)zinc(II)chloride single crystals (ii) Growth andcharacterization of KDP crystals with potassiumcarbonate as additive, (iii) Growth andCharacterization of a New Organic Non-LinearOptical (NLO) Material: L-HistidiniumTrifluoroacetate, (iv) Growth by SR method andcharacterization of hippuric acid single crystals, (v)Optical, dielectric and surface studies on solutiongrown benzimidazole single crystals, (vi) Directionalgrowth of organic NLO crystal by different growthmethods: A comparative study by means of XRD,HRXRD and laser damage threshold, (vii) Influenceof inorganic and organic additives on the crystalgrowth, properties and crystalline perfection oftris(thiourea)copper(I) chloride (TCC) crystals, (viii)The influence of Mn-doping on the nonlinear opticalproperties and crystalline perfection oftris(thiourea)zinc(II) sulphate crystals: Concentrationeffects (ix) Growth of L-histidinium bromide (LHB)single crystal and its characterization analyses bybirefringence, HRXRD and photoluminescence (x)Growth of nonlinear optical single crystal of Glycinehydrofluoride (GHF) by conventional solution growth

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method (xi) Growth of unidirectional potassiumdihydrogen orthophosphate single crystal by SRmethod and its characterization, (xii) Nanocrystallinezinc oxide powder samples were prepared by wet-chemical method and characterized by XRD, EPRand FTIR techniques and (xiii) Growth of strategicNLO crystals of lithium niobate by employing an in-house developed CZ crystal growth system and theircharacterization which is described briefly (as a typicalexample) in the following.

Lithium niobate (LiNbO3) is one of the mostattractive materials for optoelectronics due to itsunique electro-optical (E-O), Acousto-Optic (A-O),photoelastic, piezo-electric and nonlinear optical(NLO) properties combined with good mechanicaland chemical stability and wide transparency. Aftersuccessful installation of RF heating system with semi-automated and modernized in-house developedCzochralski crystal puller, we have grown goodquality crystals with larger diameters up to 40 mm tomeet the device applications by a low thermal gradientCzochralski technique. The sharp and single peakdiffraction curve having FWHM value of 23 arc sdepicts the excellent quality of the as-grown crystalrevealing the absence of cracks and internal structuralgrain boundaries. In the recent past we have donegood number of investigations on the undoped andFe doped crystals. The annealing studies with lowheating and cooling rates reveal significantimprovement in crystalline perfection which leads toimprovement in optical and piezoelectric properties.The defects like OH- and undecomposed CO3

2- ionshave been reduced as revealed by FTIR. Opticaltransparency was enhanced. The piezoelectricresponse (d33) has been improved to anunprecedented high value of 23 pC/N from the earlierreported value of 17 pC/N. These studies serve asan important input to industries related to opto-electronic, holographic storage devices etc. This work

has been carried out as a part of the CSIR NetworkProject CMM-0022/1G.

This R&D group also actively involved inhelping or collaborating various R&D projects fromother groups of NPL and various other laboratoriesand educational institutes by characterizing variety ofsingle crystal samples, epitaxial films and powdersamples by high-resolution and powder XRDtechniques. More than hundred single crystal samplesto study the crystalline perfection or to study the effectof dopants or functional groups added to the semi-organic materials have been characterized by high-resolution X-ray diffractometry. Around 600 powdersamples have also been characterized for structuralstudies and phase analysis. It is worth to mention herethe characterization of big size (82x91x91 mm3)crystals of KDP samples from RRCAT, Indore werecompleted at NPL. Such type of big and heavycrystals cannot be mounted easily on the goniometerheads of commercial diffractometers. It was madepossible with NPL developed multicrystal X-raydiffractometer system, as it is versatile to change itsconfiguration. In a non destructive way, various parts(bottom to top and left to right) of the crystal wascharacterized and found its excellent uniformity andquality for device fabrication.

Fig.5.4 A crack free lithium niobate (LiNbO3) singlecrystal and (b) high-resolution diffractioncurve of the grown crystal (Z-cut) recordedby the in-house developed multicrystal X-raydiffractometer.

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Implementation of quality system as per ISO-17025 guidelines in the group is going on. In view ofdeveloping new CRMs (certified reference material),lanthanum hexaboride (LaB6) is being studied in detailfor development as X-ray line position standard.

The important technical achievements are: (i)The crucible setup of the RF heating system of theCzochralski crystal puller has been redesigned anddeveloped with a bigger diameter RF coil for thegrowth of bigger crystals up to 50 mm dia. The heatingsystem is atomized by controlling the feeding powerof the RF coil through a Eurotherm temperaturecontroller. With this we have grown good qualitylithium niobate crystals with diameters up to 40 mmto meet the device applications, (ii) Similarly theresistive heating furnace of another Czochralski crystalpuller is also automized recently with an independentEurotherm temperature controller. With this systemwe have grown Bismuth silicon oxide (BSO) andlithium fluoride (LiF) single crystals and (iii) Forachieving intense, parallel and monochromatic beam,Gobel Mirror was installed with the Bruker D8Advance Powder X-ray Diffractometer. For the samesystem, reflectometry sample stage was alsopurchased and installed.

Electron Microscopy Electron microscopy facilities are being

utilized at NPL as the central facility for thecharacterization of materials. This group is equippedwith SEM, TEM and high resolution TEM with EDSand STEM attachements. Different types of samplesin the form of thin films, powders, and compositesprepared by various techniques have been receivedfrom different groups of NPL working on thedevelopment of new materials. These samples havebeen characterized for their particles shape, size,distribution of particles, phase identification etc., usingthese facilities.

Some of the samples which were characterizedby using TEM and HRTEM are gold nano particlesprepared through chemical route at 4 oC., 10oC androom temp., Ag nano particles, Al/Si alloy, WO3 films,Lithium ferrites prepared by different routes, Gold ongrapheme, CdTe thin films, Y2O3 powder calcinatedat different temperatures, Te doped InSb thin thin filmsat Rt and annealed at 200oC , ZnO powder dopedwith Na (2 and 10 %) and Li 2%, CNT prepared byCVD technique, Ag ions in grapheme etc..Figure 5.5shows the HRTEM bright field image of the graphene-metal nanohybrid assemblies depicting the embedingof the silver nanoparticles into graphene oxidenanosheets (a solution-based single step method thatembeds the silver nanoparticles into graphene oxidenanosheets). The opto-electronic properties of thegraphene sheets can thus be tuned over several ordersof magnitude, making them potentially useful for flexibleand transparent semiconductors or semi-metals.Incorporation of nanoparticles could represent a routefor translating the interesting fundamental properties ofgraphene into technologically viable devices. Stabledispersions of graphene could become a reliable andeconomically feasible source of an ultrahigh surfacearea substrate.

Fig. 5.5: Ag-nanoparticle (~ 15 nm) trapped betweentwo Graphene sheets acting as spacer; B:single Ag particle with hexagonal shapedalong 3-fold cubic symmetry; This material wasprepared using a facile route for the reductionof Ag using graphite oxide.

About 110 sample were received from thevarious groups of NPL working on the development

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of new and advanced materials. These sample werecharacterized by using TEM and HRTEM. Thisfacility was also extended to various industries.

Scanning Electron Microscopy (SEM) andEnergy Dispersive Spectroscopy (EDS) is anothercentral facility of the laboratory which is extensivelyused by various R & D groups of NPL, other scientificR & D institutes and Industrial organizations forcharacterization of materials for surface microstructureand chemical compositional measurement.

Some of the materials characterized by usingSEM are Al-Si powder samples, Mg-Al Alloys,Oxidase coatings, metal doped polymer films, polymerpowders and films with and without enzyme andDNA, Gold nanoparticles with and without enzymes,High Tc Superconducting, CaCuTitanate, boronnitride, Fe doped ZnO, Ceramic materials, Li-MgFerrite samples, Pr-Ba-MnO3 Composites withdifferent additives, SAM layers with PPY, TiO2 filmson different substrates, DNA, PANI plane, proteinimmobilized with and without DNA, PANI+CNTcomposites, LDPE films, CdSeTe Alloys of differentratios and at different temps, Particulate matter/filterpaper collected from different locations, Au film/ITO,gold nanoparticles with enzyme and gold nanoparticleswith pyrol, Lithium-Ce Ferrite Samples, PECVDgrown TiO2 films/Si, TiO2 films on different substratesetched with HF and NaOH treated, MgB2 Pure andwith 10% SiC samples annealed at differenttemperatures, Graphite composites with mixing ofChitosan polymer, Al, Al2O3, Al+Al2O3 powders ballmilled, La-Sr-MnO3 films/SrTiO3 substrate preparedby DC magnetron sputtering technique, Alkaline andacid texturised micro crystalline Silicon, Porus Siliconsamples, rare earth nanophophor, etc. Fe doped ZnO(Fe 0, 0.5, 2 and 50) mole % prepared by solgeltechnique and annealed at 800OC have beencharacterized by using SEM. Details of the surfacemorphology of Fe doped ZnO have shown in Fig. 5.6

More than 1000 samples have beenexamined by SEM and EDS for surfacemicrostructure and compositional analysis.

SEM and EDS facility is also used by theindustry for carrying out different type of testing and

Fig. 5.6 SEM images of Fe (0, 0.5, 2 and 50) mol%doped ZnO by sol –gel technique using ZincNitrate and Ferric chloride annealed at 800^ C

analysis work. During the period different sampleswere received from industry for particle size, shape,surface structure, fracture analysis, thickness andchemical compositional analysis. Some of theindustries for which SEM/EDS analysis were carriedout are M/s. Oriental Carbon and Chemicals Ltd.,New Delhi, M/s. Mindarika Pvt. Ltd., Gurgaon, M/s. MNIT, Jaipur, M/s. Ranbaxy R&D Lab. Gurgaon,M/s. NTPC, R&D centre Noida, Central RoadResearch Institute New Delhi, M/s. MoserBaerPhotovoltaics Ltd., Gautam Budh Nagar, M/s. KPSConsultant & Impex Pvt. Ltd. New Delhi

Secondary Ion Mass SpectrometryQuantification of the mixing effect in Silicon-Manganese thin films by swift heavy ionirradiation

Swift heavy ion (SHI) irradiation is an efficientmean to moidfy the composition and structure of thinfilms and interfaces. Amid different techniques to

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transform thin films, SHI irradiaiton find theireffectiveness in terms of its spatial selectivity, precisecontrol and low temperature process. Since earlynineties SHI induced mixing of thin films has beenstudied in various types of systems . In continuationto our previous work on Si/TM(transition metal)/Sisystems (V/Si, Fe/Si and Co/Si) we consider herethe mixing of another transition metal, Mn, withamorphous silicon (a-Si). Mn with amorphous silicon(a-Si) is chosen as hardly any detailed study has beendone on this metal/Si system in high-energy regime.Though Mn is reported to be “Se-sensitive” but wedo not have an apparent picture of its behaviouralchanges due to electronic energy loss (Se). Even theinformation about its Se-threshold value is notavailable. Therefore this system has been selectedfor SHI-induced mixing studies. This work is anattempt to quantify SHI-induced interface mixing interms of mixing rate and thereby understand thisphenomenon in the framework of thermal spike modeland secondly, to check if some silicidation has takenplace at room temperature as reported earlier byChakraborty et al.

Swift heavy ion induced mixing is reported inSi/Mn/Si thin films on a silicon wafer, when irradiatedby 120 MeV Au ions at three different fluences of 1x1013, 3x 1013 and 1x 1014 ions/cm2. The samples werecharacterized before (pristine) and after irradiationusing Secondary Ion Mass Spectroscopy (SIMS)and Rutherford Backscattering Spectroscopy(RBS)Fig. 5.7. Atomic Force Microscopy (AFM)of the samples was used to determine surfaceroughness contribution to RBS and SIMS profiles.Depth profiles Fig. 5.8 showed distinct changes inthe interface region and it was observed that interfacemixing increased linearly with the increase in the ionfluence. The mixing rate was estimated to be ~1000nm4. The mixing effect was studied in the frameworkof thermal spike model.The track radius and duration

of the transient melt phase have been theoreticallycalculated for this system to estimate the diffusivityduring the transient melt stage at the interface.

Fig.5.8 SIMS depth profile of Si/Mn/Si interface beforeirradiation (a) and after irradiation with (b) 1x1014 ions cm-2.

Fig. 5.7 RBS-spectrum of the pristine Si/Mn/Si.

(a)

(b)