research article investigating the formation process of sn...

Hindawi Publishing CorporationJournal of NanomaterialsVolume 2013 Article ID 193725 9 pageshttpdxdoiorg1011552013193725

Research ArticleInvestigating the Formation Process of Sn-Based Lead-FreeNanoparticles with a Chemical Reduction Method

Weipeng Zhang12 Bingge Zhao12 Changdong Zou2 Qijie Zhai2

Yulai Gao123 and Steve F A Acquah3

1 Laboratory for Microstructures Shanghai University 99 Shangda Road Shanghai 200436 China2 School of Materials Science and Engineering Shanghai University 149 Yanchang Road Shanghai 200072 China3Department of Chemistry amp Biochemistry The Florida State University Tallahassee FL 32306-4390 USA

Correspondence should be addressed to Yulai Gao ylgaoshueducn and Steve F A Acquah sacquahchemfsuedu

Received 22 October 2012 Revised 15 January 2013 Accepted 29 January 2013

Academic Editor Xuedong Bai

Copyright copy 2013 Weipeng Zhang et alThis is an open access article distributed under the Creative CommonsAttribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Nanoparticles of a promising lead-free solder alloy (Sn35Ag (wt SnAg) and Sn30Ag05Cu (wt SAC)) were synthesizedthrough a chemical reduction method by using anhydrous ethanol and 110-phenanthroline as the solvent and surfactant respec-tively To illustrate the formation process of Sn-Ag alloy based nanoparticles during the reaction X-ray diffraction (XRD) wasused to investigate the phases of the samples in relation to the reaction time Different nucleation and growth mechanisms werecompared on the formation process of the synthesized nanoparticlesTheXRD results revealed different reaction process comparedwith other researchersThere weremany contributing factors to the difference in the examples found in the literature with themainfocus on the formation mechanism of crystal nuclei the solubility and ionizability of metal salts in the solvent the solid solubilityof Cu in Ag nuclei and the role of surfactant on the growth process This study will help define the parameters necessary for thecontrol of both the composition and size of the nanoparticles

1 Introduction

Interconnect (solder-based)materials are of great importancein the field of electronics and manufacturing and the mostwidely used solder is an Sn-Pb-based alloy However the verynature of the levels of toxicity with lead in this system hasbeen a persistent issue and is therefore being phased out inthe electronic industry gradually The development of viablealternatives has focused on many alloy-based systems suchas Sn-Cu [1] Sn-Ag [2] Sn-Zn [3] Sn-Bi [4] and Sn-In [5]To improve the properties of these binary alloy solders athird element can be introduced A Sn-Ag-Cu system [6] wasdeveloped to investigate this potential

The most promising candidates for Sn-Pb solders are Sn-Ag-based alloys with benefits extending towards the solder-ability mechanical properties and the reliability [7] Thereare however some disadvantages in this system One ofthem is the higher melting temperature than that of Sn-Pbsolder which may cause some damages during the solderingprocess To solve this problem the size-dependent melting

temperature of the pure melt and alloy has been studied [8ndash13] These works show that the nanoparticles melt at a lowertemperature than the corresponding bulk ones Thus thepreparation of nanoparticles is extremely important

Many methods have been developed to manufacturenanoparticles [14ndash17] Among them the chemical reductionmethod is widely used in the production of nanoparticles oflead-free solder [18ndash20] There has been a significant focuson the physical properties of products However little workhas been done on the formation process of the nanoparticlesof Sn-Ag during the reaction process The nucleation andgrowth mechanism are still not fully understood Hsiaoand Duh studied this issue in the synthesis process ofSn35Ag05Cu nanoparticles in aqueous solution [21] How-ever their explanations about the disappearance of Cu in theXRD pattern are still speculative

In this paper nanoparticles of two promising lead-freesolders the Sn35Ag (wt) alloy and the Sn30Ag05Cu(wt) alloy were synthesized through a chemical reductionmethod We studied the formation process of nanoparticles

2 Journal of Nanomaterials

Table 1 Synthesis parameters of SnAg nanoparticles

Sample C16H30O4Sn (g) AgNO3 (g) CH3CH2OH (mL) C12H8N2 sdotH2O (g) NaBH4 (g) Reaction time (min)SnAg1 02998 00051 60 02775 01892 15SnAg2 02998 00051 60 02775 01892 30SnAg3 02998 00051 60 02775 01892 45SnAg4 02998 00051 60 02775 01892 g 60

Table 2 Synthesis parameters of SAC nanoparticles

Sample C16H30O4Sn(g)

AgNO3(g)

Cu(OC2H5)2 sdotH2O(g)

CH3CH2OH(mL)

C12H8N2 sdotH2O(g)

NaBH4(g)

Reaction time(min)

SAC1 03293 00047 00017 60 02220 01892 15SAC2 03293 00047 00017 60 02220 01892 30SAC3 03293 00047 00017 60 02220 01892 45SAC4 03293 00047 00017 60 02220 01892 60

in an anhydrous ethanol solution during the reaction Manyexperimental parameters were considered to help explain thedifferences in the XRD patterns found in the literature

2 Experimental

The materials used to synthesize Sn35Ag nanoparticleswere tin(II) 2-ethylhexanoate (C

16H30O4Sn) and silver

nitrate (AgNO3) 110-phenanthroline (C

12H8N2sdotH2O)

sodium borohydride (NaBH4) and anhydrous ethanol

(CH3CH2OH) were selected as the surfactant reducing

agent and solvent respectively In terms of the synthesis ofSn30Ag05Cu (SAC) nanoparticles copper (II) ethoxidemonohydrate (Cu(OC

2H5)2sdotH2O) was added to the reactant

In a typical synthesis of Sn35Ag nanoparticles 02998 gof tin (II) 2-ethylhexanoate 00051 g of silver nitrate and02775 g of 110-phenanthroline were mixed with 60mL ofanhydrous ethanol to prepare the precursor solution Themixture was stirred for about 2 hours before 01892 g ofsodiumborohydridewas added into the stirring solutionThereaction timewas the variable to be tested in the experimentalprocedure so set reaction times of 15min 30min 45minand 60min were usedThe as-synthesized nanoparticles wereprecipitated by a centrifuge at a rate of 4000 rpm for 45minDue to the low solubility of NaBH

4in ethanol [22] the

reaction rate during the separation process was extremelylowThe reduction reaction could be stopped at any predeter-mined time through thismethodThe nanoparticles obtainedwere rinsed 3 times with anhydrous ethanol and then driedin the vacuum chamber at 40∘C for 8 hours The synthesisprocedure of Sn30Ag05Cu nanoparticles was similar to thatof Sn35Ag nanoparticles

The synthesis parameters of these two lead-free nanopar-ticles with different reaction times were listed in Tables 1 and2 respectively

The crystal structure of the synthesized SnAg alloynanoparticles was characterized by X-ray diffraction (XRD)from20∘ to 90∘ (2120579) usingCuK120572 radiation (120582= 0154056 nm)on a Rigaku DMax-2550 X-ray diffractometer The electron

accelerating voltage and accelerating current used in thedetection process were 40 kV and 200mA respectively

The SAC particle samples were measured on a RigakuDMax-2200 X-ray diffractometer from 20∘ to 90∘ (2120579) Thewavelength of the X-ray from the Cu K120572 radiation was0154056 nm The electron accelerating voltage and acceler-ating current used in the detection process were 40 kV and40mA respectively The surface features of the synthesizedparticles were studied by using a scanning electron micro-scope (SEM model JSM-6700F)

3 Results and Discussion

31 Formation Process of SnAg Nanoparticles Figure 1 showsthe XRD results of the synthesized SnAg nanoparticlesTherewere two clear phases the 120573-Sn and Ag

3Sn indicating the

successful alloying of Sn and Ag during the synthesis processThis was further confirmed through their crystal struc-tures by high resolution transmission electron microscopy(HRTEM) [23] The relative intensity of the diffraction peaksof 120573-Sn increased with the reaction time while the Ag

3Sn

phase showed the opposite trendThe relative intensity of the three strong peaks from the

Ag3Sn phase obtained from the XRD pattern was shown

in Figure 2 It was obvious that the relative intensity of thestrongest peak declined from 100 to 10 A similar trendcould be found in the other two strong peaks It tendedtowards stability when the reaction time increased from40min to 60min

The relative intensity of the diffraction peak of the Ag3Sn

phase indicted the formation process of the twophasesWhenthe reaction time was 15min the relative intensity of thediffraction peak of the Ag

3Sn phase was at the maximum

At the same time the diffraction peak of 120573-Sn phase couldalso be found as shown in Figure 1(a) This implied that theproduct was mainly in the Ag

3Sn phase When the reaction

time increased to 30min the relative intensity of the diffrac-tion peak of Ag

3Sn phase in the synthesized nanoparticles

decreased dramatically as shown in Figure 2 The maximum

Journal of Nanomaterials 3

Inte

nsity

(au

)

20 30 40 50 60 70 80 902120579 (deg)

SnAg115min

SnAg3Sn

998786

998786

998786 998786 998786998786998786

(a)

Inte

nsity

(au

)

20 30 40 50 60 70 80 902120579 (deg)

SnAg2 30min

(b)

Inte

nsity

(au

)

20 30 40 50 60 70 80 902120579 (deg)

SnAg3 45min

(c)

20 30 40 50 60 70 80 90In

tens

ity (a

u)

2120579 (deg)

SnAg4 60min

(d)

Figure 1 XRD pattern of the synthesized SnAg nanoparticles with different reaction times

15 30 45 600

20

40

60

80

100

Peak 3 Peak 4 Peak 5

Reaction time (min)

119868(

)

Figure 2 The relative intensity of three strong peaks of the Ag3Sn

phase with different reaction times

relative intensity corresponds to the main peak of the 120573-Snphase and therefore the amount of the 120573-Sn phase increasedin the product The result was the same for the nanoparticlesobtained when the reaction time was further increased to45min The reaction was near completion when the reactiontime was set to 60min and the main phase changed to 120573-Sn

with the relative amount of the Ag3Sn phase decreasing to a

very low level which could be derived from Figures 1 and 2Hsiao and Duh [21] had studied the formation process

of Sn35Ag05Cu alloy nanoparticles by means of a chemicalreduction method in aqueous solution The precursor wasmade by mixing SnSO

4 AgNO

3 and Cu(NO

3)sdot25H

2O

together in the solvent The reducing agent (NaBH4NaOH)

was added to the precursor and the products and reactiontimes were investigated In their work the formation pro-cess of Sn35Ag05Cu nanoparticles was divided into stagesFirstly the Ag-Cu nuclei formed in the solution beforebeing transformed to (Ag Cu)

4Sn by adsorbing tin atoms

The second stage involved the growth of the (Ag Cu)4Sn

nanoparticles It was noted that (Ag Cu)3Sn formedwhen the

tin atoms in the (Ag Cu)4Sn phase exceeded the maximum

amountAnother change from the reported literature procedure

was the use of anhydrous ethanol as the solvent in our exper-imentThere were Sn2+ and Ag+ ions in the aqueous solutionand due to the different standard reduction potential ofSn2+Sn4+ (0151 V versus the standard hydrogen electrodeSHE) and Ag+Ag (08 V versus SHE) the following reactionwould occur [24]

Sn2+(aq) + 2Ag

+997888rarr Sn4+

(aq) + 2Ag (1)The (Ag Cu)

4Sn phase could be generated without the

addition of a reducing agent in reference [21] However theorigin of Ag atoms was not specified Using (1) it can be seenthat the silver atoms came from two reaction mechanisms atthe first stage Both Sn2+ and NaBH

4could reduce Ag+


Inte

nsity

(au

)

20 30 40 50 60 70 80 902120579 (deg)

SAC1 15min

Sn(2

00)

Sn(1

12)

Ag 3

Sn(2

11)

Cu6Sn5(3

14)

(a)

Inte

nsity

(au

)

20 30 40 50 60 70 80 902120579 (deg)

SAC2 30min

Sn(1

01)

Sn(2

20)

(b)

Inte

nsity

(au

)

20 30 40 50 60 70 80 902120579 (deg)

SAC3 45min

Sn(2

11)

Sn(3

01)

Sn(4

00)

Sn(4

20)

Sn(3

12)

Sn(4

31)

(c)

20 30 40 50 60 70 80 90

Inte

nsity

(au

)2120579 (deg)

SAC4 60min

Sn(3

21)

Sn(4

11)

(d)

Figure 3 XRD pattern of the synthesized SAC nanoparticles with different reaction times

Figure 4 Typical SEM image of the synthesized SAC nanoparticleswith a reaction time of 60min

If the solvent was changed to anhydrous ethanol whichwas studied in the present work the solubility of AgNO

3

would be low [25 26] Although AgNO3could be ionized

in ethanol [27 28] the amount was possibly small due tothe difference of molecular polarity between solvent andsolute The reaction in (1) did not take place which could beconfirmed by the experimental phenomena that no changeoccurred during the preparation process of metal precursor

When the reducing agent NaBH4was added into the

precursor black particles precipitated rapidly In the homo-geneous metal ion solutions electron transfer from NaBH

4

to the metal ions occurred during the redox reaction [29 30]

thus the metal ions turned into atoms This process could bedescribed as follows [31]

2Ag+ + 2BH4

minus997888rarr 2Ag +H

2+ B2H6

(2)Sn2+ + 2BH

4

minus997888rarr Sn +H

2+ B2H6

(3)

The transition of electrons from the reducing agent to themetal ionswas determined by their standard redox potentialsThe reduction rate of cations increased with the standardredox potentials increase [32] The standard redox potentialof AgAg+ and SnSn2+ was 08V (versus SHE) [24 33] and014V (versus SHE) [34] respectively The principles were

Ag+ + e = Ag E0 = 0799V (4)

Sn2+ + 2e = Sn E0 = minus0140V (5)

It could be seen that the standard redox potential ofAgAg+ was much higher than that of SnSn2+ Thus the oxi-dizing ability of Ag+ was larger compared with Sn2+ It wasthe same for their reduction rate in the reaction systemwhichwas consistent with the XRD resultsTherefore the formationprocess of Sn35Ag nanoparticles in this work could besummarized

Before the addition of reducing agent themetal salts weredissolved homogeneously by stirring for 2 hours in anhydrousethanol The potential for ionization was relatively low as thepolarity was different from that of solvent

When the reducing agent was added and mixed intothe precursor black particles precipitated immediately Atthis stage most of the Ag+ ions were reduced by NaBH

4


Ag nucleus

Cu nucleus

Sn atom

Sn nucleus

Capping effectSurfacant

nanoparticle

nanoparticle

Sn nanoparticle

Nanoparticle formation

Ag+ Sn2+Sn2+

Cu2+

Ag3Sn

Ag3Sn

Cu6Sn5

Cu6Sn5

BHminus4

BHminus4

Figure 5 The formation process of SAC nanoparticles

Only a few Sn2+ ions were reduced owing to the relativelylower oxidization potential and reduction rate Silver atomsand tin atoms derived from the redox reaction formed theintermetallic compound (Ag

3Sn) through the mechanical

stirring Because of the low silver content some of the tinatoms did not combinewith silver atoms and formed the120573-Snphase

The reduction of Sn2+ ions continued till the completionof the reaction until the Sn35Ag alloy nanoparticles wereobtained

32 Formation Process of the Primary Nanoparticles of theSnAgCu Alloy System The influence of Cu added to theSnAg alloy for the formation process of nanoparticles wasstudied in this section Different reaction times were chosenas shown in Table 2 and the corresponding XRD results wereshown in Figure 3

Figure 3 indicated that the products formed in the ini-tial 15min were mainly Ag

3Sn Cu

6Sn5 and 120573-Sn Only 5

diffraction peaks of 120573-Sn emerged in this sample Sn2+ ionsin the solution were not sufficiently reduced at this reactionstage After 30 minutes of reaction the XRD pattern of theSAC2 sample showednoobvious differencewith that of SAC1except for the change in themaximum relative intensity of the120573-Sn phase from (200) to (101) When the reaction durationwas set to 45min the diffraction peaks of 120573-Sn emerged as

shown in Figure 3(c) The relative intensity of the diffractionpeaks of Ag

3Sn and Cu

6Sn5decreased further There was no

significant change in the XRD patterns between SAC4 witha reaction time of 60min and SAC3

As for the Sn30Ag05Cu alloy the standard redox poten-tial of AgAg+ CuCu2+ and SnSn2+ was 08V (versus SHE)[24 33] 0339V (versus SHE) [35 36] and minus014V (versusSHE) [34] respectively So the oxidizing abilities of themetalcations in order were Ag+ Cu2+ and Sn2+ The reductionreaction of Cu2+ followed (6) and Cu atom formed throughthe electrons transmission from the reducing agent to the Cucation

Cu2+ + 2BH4

minus997888rarr Cu +H

2+ B2H6

(6)

It was thought that the Ag-Cu nuclei formed because thestandard redox potentials of these two species were similarThe Sn atoms reduced in the solution adsorbed on the surfaceof Ag-Cu nuclei which acted as the core and formed a shellthrough the diffusion mechanismThe omission of Cu in theXRD pattern was explained through crystallography whichshowed that the Cu atoms dissolved in the Ag matrix andformed a solid in solution

In order to understand the origin of the difference thesynthesis conditions and the mechanism of nucleation andgrowthwere considered Firstly the solubility and ionizability


of the reactant AgNO3in anhydrous ethanol solution were

much smaller than those of aqueous solution [24ndash27] andthat would lead to the relatively low reaction rate (the relativeintensity of the XRD pattern of Sn phase was strong enoughwhen the reaction time was 10 seconds [21] compared withthat in this paper) so the metal cations could be reduced toatoms at a relatively slow rate compared with that in aqueoussolution Secondly Ag and Cu in their metallic form couldform nuclei separately in the initial stage of the reactionThere were three main nucleation or growth mechanismsin the colloidal system The classic Lamer mechanism [37]proposed the idea that fast nucleation and slow growth tookplace in the supersaturated solution The growth process wascontrolled by diffusion However this mechanism was con-sidered to be suitable to the sulfur sols and other analogoussystems [38] The Finke mechanism [38] which was reason-able for the unsaturated solutions showed that nanoparticleformation was dominated by low continuous nucleation andfast autocatalytic surface growthThe last growthmechanismwas described as the seeded growth [39]The seeds which actas the nuclei for the growth process could be either the sameor different composition as the absorbed atoms This growthmechanism was used to fabricate the core-shell structures inthe bimetallic alloy system [40] In the case of the presentwork when the reducing agent was added into the precursorsolution the nucleation and growth process of intermetalliccompound nanoparticles could be described by the Finkemechanism

Luo et al synthesized ZnPd nanoparticles through achemical reduction method and found that the coreductionof Zn2+ and Pd2+ could happen when the reducing agentwas in excess [41] The conditions were similar in this workand the metal cations (Ag+ Cu2+ and Sn2+) with differentreduction potentials could be reduced simultaneouslyMean-while the reduction rate of Ag+ and Cu2+ was faster thanthat of Sn2+ due to their reduction potentials [32]There weremore Ag and Cu atoms than Sn atoms in the solution at theinitial reaction stage and as a result of this the coreductionof intermetallic compounds that is Ag

3Sn andCu

6Sn5 could

take place Due to the relatively low content of Ag and Cu theSn in the solutionwas not consumed in the formation processof the intermetallic phase and the Sn phase in the XRDwas made up of these Sn atoms The growth of the formedSn nuclei might combine the autocatalytic surface growthmechanism and homogeneous seeded growth mechanism

In addition the surfactant used in our experiment whichwas different from that used in literature may play animportant role in the detection of Cu The capping effect of110-phenanthroline on the formation of metal nanoparticleshas already been well documented [42ndash53] The passivationlayer could effectively prevent the growth of the primaryparticles or the formation of the secondary particles that isaggregation andOstwald-Ripening process [54 55] A typicalSEM image of the SAC nanoparticles (SAC4) synthesizedat room temperature with a reaction time of 60min wasshown in Figure 4The particles were basically spherical witha narrow diameter distribution of 376plusmn149 nm Despite thelow content of Cu in the core-shell structure the relatively

small particle size could make it detectable The formationprocess of SAC nanoparticles was illustrated in Figure 5

There was another question concerning whether the Ag-Cu nuclei could actually be formed Hume-Rothery ruleswere employed to prove the existence of nuclei of thisspecie in the literature [21] In fact the Ag-Cu system wasalmost absolutely immiscible at room temperature whichviolated the Hume-Rothery rules [56 57] Moreover thelattice constant of the Ag-Cu solid solution should be smallerthan that of Ag owing to the lattice contraction caused by thesubstitution of Cu atoms to Ag atoms However the contraryresult was obtained when the Ag-Cu nanoparticles wereannealed at 300K [58] When the temperature increased to493K the diffusion of Ag and Cu was rather difficult whichindicated poor solubility [59] A study on the equilibriumsolubility of Cu in Ag showed that the substitution of asolid solution could be formed only when the samples wasannealed at temperature near 653K [60] So theAg-Cunucleiand the following (Ag Cu)

3Sn phase were not recommended

considering this result One of the possible reasons for thedisappearance of Cu in Duhrsquos work was the relatively largeagglomeration rate of Sn atoms at the surface of Cu nucleiThe Sn shell in the nanoparticles was too thick for theX-ray to detect the Cu phases Other reasons should betaken into consideration For example the aggregation tookplace during the growth process because of the absence thesurfactant acting as a protective medium

In summary the formation process of SAC nanoparticlescould be divided into three stages similar to that of SnAgnanoparticles First the metal salts were mixed in anhydrousethanol The mixture was intensely stirred for 2 hours toproduce a uniformprecursor solution Second black particlesprecipitated when the reducing agent was added into theprecursor Most of the Ag and Cu cations were reduced totheir metallic form and formed nuclei respectively At thesame time a few Sn atoms were generated in the solutionWith mechanical agitation the nuclei of Ag and Cu actedas the heterogeneous seed absorbed Sn atoms and formedthe intermetallic phases Ag

3Sn and Cu

6Sn5 The rest of the

Sn atoms that were not used in the formation process ofthe intermetallic phases could nucleate and grew into the Snphase The capping effect of the surfactant and the size of thesynthesized nanoparticles can be well controlled This stagecan also be described by the following reaction equations

2Ag+ + 2BH4


2+ B2H6

(7)

Cu2+ + 2BH4


2+ B2H6

(8)

Sn2+ + 2BH4


2+ B2H6

(9)

Ag(reacted) + Sn(reacted) 997888rarr Ag

3Sn + Sn

(unreacted) (10)

Cu(reacted) + Sn(reacted) 997888rarr Cu

6Sn5+ Sn(unreacted) (11)

Finally the Sn cations in the solution continued to bereduced until the termination of the reaction which can bedescribed as (3)


4 Conclusions

A chemical reduction method was used to synthesize lead-free alloy nanoparticles for use as a solder The nucleationand growth mechanism in the anhydrous ethanol solutionwas discussed and due to the difference in the redoxpotential the Ag and Cu cations were reduced faster than Sncations The limited solubility of the reactant in the solventensured that the redox reaction took place The immisciblenature of Cu and Ag at room temperature meant that thesetwo species nucleated through the Finke mechanism sepa-rately The nucleus acted as the heterogeneous seed duringthe growth process of the intermetallic compound Thenucleation mechanism of the Sn phase was similar to thatof Ag and Cu while the growth followed the homogeneousseeded mechanism Moreover the surfactant could controlthe size of the synthesized nanoparticles during the growthprocess through a capping effect The relatively thin Sn shellsurrounded the intermetallic core and the light aggregationof the primary nanoparticles made the Cu detectable in theXRD pattern

Acknowledgment

This work is supported by the National Natural ScienceFoundation of China (Grant nos 50971086 and 51171105)

References

[1] M F Arenas M He and V L Acoff ldquoEffect of flux on thewetting characteristics of SnAg SnCu SnAgBi and SnAgCulead-free solders on copper substratesrdquo Journal of ElectronicMaterials vol 35 no 7 pp 1530ndash1536 2006

[2] J H Lee and Y B Park ldquoAbnormal failure behavior of Sn-35Ag solder bumps under excessive electric current stressingconditionsrdquo Journal of Electronic Materials vol 38 no 10 pp2194ndash2200 2009

[3] Y M Hung and C M Chen ldquoElectromigration of Sn-9wtZnsolderrdquo Journal of ElectronicMaterials vol 37 no 6 pp 887ndash8932008

[4] F Guo G Xu H He M Zhao J Sun and C H Wang ldquoEffectof electromigration and isothermal aging on the formation ofmetal whiskers and hillocks in eutectic Sn-Bi solder joints andreaction filmsrdquo Journal of ElectronicMaterials vol 38 no 12 pp2647ndash2658 2009

[5] H Y Guo J D Guo and J K Shang ldquoInfluence of thermalcycling on the thermal resistance of solder interfacesrdquo Journalof Electronic Materials vol 38 no 12 pp 2470ndash2478 2009

[6] I Ohnuma M Miyashita K Anzai et al ldquoPhase equilibria andthe related properties of Sn-Ag-Cu based Pb-free solder alloysrdquoJournal of Electronic Materials vol 29 no 10 pp 1137ndash11442000

[7] T Siewert S Liu D R Smith and J C Madeni ldquoDatabase forsolder properties with emphasis on new lead-free soldersrdquoNISTamp Colorado School of Mines Release vol 4 2002

[8] P Buffat and J P Borel ldquoSize effect on the melting temperatureof gold particlesrdquo Physical Review A vol 13 no 6 pp 2287ndash2298 1976

[9] W A Jesser G J Shiflet G L Allen and J L Crawford ldquoEqui-librium phase diagrams of isolated nano-phasesrdquo MaterialsResearch Innovations vol 2 no 4 pp 211ndash216 1999

[10] J Lee J Lee T Tanaka H Mori and K Penttila ldquoPhase dia-grams of nanometer-sized particles in binary systemsrdquo Journalof Management vol 57 no 3 pp 56ndash59 2005

[11] M Lucic Lavcevic and Z Ogorelec ldquoMelting and solidificationof Sn-clustersrdquoMaterials Letters vol 57 pp 4134ndash4139 2003

[12] C R MWronski ldquoThe size dependence of the melting point ofsmall particles of tinrdquo British Journal of Applied Physics vol 18no 12 pp 1731ndash1737 1967

[13] W A Jesser R Z Shneck andWW Gile ldquoSolid-liquid equilib-ria in nanoparticles of Pb-Bi alloysrdquo Physical Review B vol 69no 14 Article ID 144121 2004

[14] J S Benjamin ldquoDispersion strengthened superalloys by me-chanical alloyingrdquo Metallurgical Transactions vol 1 no 10 pp2943ndash2951 1970

[15] R Birringer H Gleiter H P Klein and P Marquardt ldquoNano-crystalline materials an approach to a novel solid structure withgas-like disorderrdquo Physics Letters A vol 102 no 8 pp 365ndash3691984

[16] I T H Chang and Z Ren ldquoSimple processing method andcharacterisation of nanosizedmetal powdersrdquoMaterials Scienceand Engineering A vol 375-377 no 1-2 pp 66ndash71 2004

[17] C H Bernard Ng J Yang and W Y Fan ldquoSynthesis and self-assembly of one-dimensional sub-10 nm Ag nanoparticles withcyclodextrinrdquo Journal of Physical Chemistry C vol 112 no 11pp 4141ndash4145 2008

[18] H J Jiang K SMoon and C PWong ldquoTinsilvercopper alloynanoparticle pastes for low temperature lead-free interconnectapplicationsrdquo in Proceedings of the 58th Electronic Componentsand Technology Conference (ECTC rsquo08) pp 1400ndash1404 May2008

[19] L Y Hsiao and J G Duh ldquoSynthesis and characterizationof lead-free solders with Sn-35Ag-xCu (x = 02 05 10) alloynanoparticles-by the chemical reductionmethodrdquo Journal of theElectrochemical Society vol 152 no 9 pp J105ndashJ109 2005

[20] H Jiang K S Moon F Hua and C P Wong ldquoSynthesis andthermal and wetting properties of tinsilver alloy nanoparticlesfor low melting point lead-free soldersrdquo Chemistry of Materialsvol 19 no 18 pp 4482ndash4485 2007

[21] L Y Hsiao and J G Duh ldquoRevealing the nucleation andgrowth mechanism of a novel solder developed from Sn-35Ag-05Cu nanoparticles by a chemical reduction methodrdquo Journalof Electronic Materials vol 35 no 9 pp 1755ndash1760 2006

[22] X Yang Q Wang Y Tao and H Xu ldquoA modified method toprepare diselenides by the reaction of selenium with sodiumborohydriderdquo Journal of Chemical Research no 4 pp 160ndash1612002

[23] C Zou Y Gao B Yang and Q Zhai ldquoNanoparticles ofSn30Ag05Cu alloy synthesized at room temperature with largemelting temperature depressionrdquo Journal of Materials Sciencepp 1ndash6 2011

[24] W Lee R Scholz K Nielsch and U Gosele ldquoA template-basedelectrochemical method for the synthesis of multisegmentedmetallic nanotubesrdquo Angewandte Chemie vol 44 no 37 pp6050ndash6054 2005

[25] C Wang X Zhang X Qian W Wang and Y Qian ldquoUltrafinepowder of silver sulfide semiconductor prepared in alcoholsolutionrdquo Materials Research Bulletin vol 33 no 7 pp 1083ndash1086 1998

[26] X F Qian J Yin S Feng S H Liu and Z K Zhu ldquoPreparationand characterization of polyvinylpyrrolidone films containingsilver sulfide nanoparticlesrdquo Journal of Materials Chemistry vol11 no 10 pp 2504ndash2506 2001


[27] A Y Robin J L Sague andKM Fromm ldquoOn the coordinationbehaviour of NOminus

3in coordination compounds with Ag+ part 1

Solubility effect on the formation of coordination polymer net-works between AgNO

3and L (L = ethanediyl bis(isonicotinate)

as a function of solventrdquo CrystEngComm vol 8 no 5 pp 403ndash416 2006

[28] M Szymanska-Chargot A Gruszecka A Smolira et al ldquoFor-mation of nanoparticles and nanorods via UV irradiation ofAgNO

3solutionsrdquo Journal of Alloys and Compounds vol 486

no 1-2 pp 66ndash69 2009[29] A Corrias G Ennas G Licheri GMarongiu and G Paschina

ldquoAmorphous metallic powders prepared by chemical reductionof metal ions with potassium borohydride in aqueous solutionrdquoChemistry of Materials vol 2 no 4 pp 363ndash366 1990

[30] D Zeng and M J Hampden-Smith ldquoSynthesis and character-ization of nanophase group 6 metal (M) and metal carbide(M2C) powders by chemical reduction methodsrdquo Chemistry ofMaterials vol 5 no 5 pp 681ndash689 1993

[31] LMulfinger S D SolomonM Bahadory A V JeyarajasingamS A Rutkowsky and C Boritz ldquoSynthesis and study of silvernanoparticlesrdquo Journal of Chemical Education vol 84 pp 322ndash325 2007

[32] R G Reifler and B F Smets ldquoEnzymatic reduction of 246-trinitrotoluene and related nitroarenes kinetics linked to one-electron redox potentialsrdquo Environmental Science and Technol-ogy vol 34 no 18 pp 3900ndash3906 2000

[33] O S Ivanova and F P Zamborini ldquoSize-dependent elec-trochemical oxidation of silver nanoparticlesrdquo Journal of theAmerican Chemical Society vol 132 no 1 pp 70ndash72 2010

[34] M M P Janssen and J Moolhuysen ldquoState and action of the tinatoms in platinum-tin catalysts for methanol fuel cellsrdquo Journalof Catalysis vol 46 no 3 pp 289ndash296 1977

[35] F Kooli V Rives and W Jones ldquoReduction of Ni2+-Al3+ andCu2+-Al3+ layered double hydroxides to metallic Ni0 and Cu0via polyol treatmentrdquo Chemistry of Materials vol 9 no 10 pp2231ndash2235 1997

[36] R Qiu X L Zhang R Qiao Y Li Y I Kim and Y S KangldquoCuNi dendritic material synthesis mechanism discussionand application as glucose sensorrdquo Chemistry of Materials vol19 no 17 pp 4174ndash4180 2007

[37] V K Lamer and R H Dinegar ldquoTheory production andmechanism of formation of monodispersed hydrosolsrdquo Journalof the American Chemical Society vol 72 no 11 pp 4847ndash48541950

[38] M A Watzky and R G Finke ldquoTransition metal nanoclusterformation kinetic and mechanistic studies A new mechanismwhen hydrogen is the reductant slow continuous nucleationand fast autocatalytic surface growthrdquo Journal of the AmericanChemical Society vol 119 no 43 pp 10382ndash10400 1997

[39] H Yu P C Gibbons K F Kelton and W E Buhro ldquoHet-erogeneous seeded growth a potentially general synthesis ofmonodisperse metallic nanoparticlesrdquo Journal of the AmericanChemical Society vol 123 no 37 pp 9198ndash9199 2001

[40] G Schmid H West J O Malm J O Bovin and C GrentheldquoCatalytic properties of layered gold-palladium colloidsrdquo Ange-wandte Chemie vol 35 no 17 pp 1099ndash1103 1996

[41] Y Luo Y Sun U Schwarz and M Armbruster ldquoSystematicexploration of synthesis pathways to nanoparticulate ZnPdrdquoChemistry of Materials vol 24 pp 3094ndash3100 2012

[42] W W Brandt F P Dwyer and E C Gyarfas ldquoChelate com-plexes of 110-phenanthroline and related compoundsrdquo Chem-ical Reviews vol 54 no 6 pp 959ndash1017 1954

[43] J Ferguson C J Hawkins N A P Kane-Maguire and HLip ldquoAbsolute configurations of 110-phenanthroline and 221015840-bipyridine metal complexesrdquo Inorganic Chemistry vol 8 no 4pp 771ndash779 1969

[44] J Gallagher C H B Chen C Q Pan D M Perrin Y M Choand D S Sigman ldquoOptimizing the targeted chemical nucleaseactivity of 110- phenanthroline-copper by ligandmodificationrdquoBioconjugate Chemistry vol 7 no 4 pp 413ndash420 1996

[45] N H Jang J S Suh and M Moskovits ldquoEffect of surfacegeometry on the photochemical reaction of 110-phenanthrolineadsorbed on silver colloid surfacesrdquo Journal of Physical Chem-istry B vol 101 no 41 pp 8279ndash8285 1997

[46] M C Lim E Sinn and R B Martin ldquoCrystal structure ofa mixed-ligand complex of copper(II) 110-phenanthrolineand glycylglycine dianion glycylglycinato(110-phenanthro-line)copper(II) trihydraterdquo Inorganic Chemistry vol 15 no 4pp 807ndash811 1976

[47] M Muniz-Miranda ldquoSurface enhanced Raman scattering andnormal coordinate analysis of 110-phenanthroline adsorbed onsilver solsrdquo Journal of Physical Chemistry A vol 104 no 33 pp7803ndash7810 2000

[48] C Pettinari M Pellei M Miliani et al ldquoTin(IV) and organ-otin(IV) complexes containing mono or bidentate N-donorligands III1 1-methylimidazole derivatives synthesis spectro-scopic and structural characterizationrdquo Journal of Organometal-lic Chemistry vol 553 no 1-2 pp 345ndash369 1998

[49] S SarkarM Pradhan A K SinhaM Basu and T Pal ldquoChelateeffect in surface enhanced Raman scattering with transitionmetal nanoparticlesrdquoThe Journal of Physical Chemistry Lettersvol 1 no 1 pp 439ndash444 2010

[50] D S Sigman ldquoNuclease activity of 110-phenanthroline-copperionrdquo Accounts of Chemical Research vol 19 no 6 pp 180ndash1861986

[51] Y Wang and J Y Lee ldquoMolten salt synthesis of tin oxidenanorodsmorphological and electrochemical featuresrdquo Journalof Physical Chemistry B vol 108 no 46 pp 17832ndash17837 2004

[52] Y Wang J Y Lee and T C Deivaraj ldquoControlled synthesis ofV-shaped SnO

2nanorodsrdquo Journal of Physical Chemistry B vol

108 no 36 pp 13589ndash13593 2004[53] C Yoon M D Kuwabara A Spassky and D S Sigman

ldquoSequence specificity of the deoxyribonuclease activity of 110-phenanthroline-copper ionrdquo Biochemistry pp 2116ndash2121 1990

[54] I M Lifshitz and V V Slyozov ldquoThe kinetics of precipitationfrom supersaturated solid solutionsrdquo Journal of Physics andChemistry of Solids vol 19 no 1-2 pp 35ndash50 1961

[55] C Wagner ldquoTheorie der alterung von niederschlagen durchumlosen (Ostwald-Reifung)rdquo Zeitschrift Fur ElektrochemieBerichte Der Bunsengesellschaft Fur Physikalische Chemie vol65 pp 581ndash591 1961

[56] H W Sheng G Wilde and E Ma ldquoThe competing crystallineand amorphous solid solutions in the Ag-Cu systemrdquo ActaMaterialia vol 50 no 3 pp 475ndash488 2002

[57] P R Subramanian and J H Perepezko ldquoThe ag-cu (silver-copper) systemrdquo Journal of Phase Equilibria vol 14 no 1 pp62ndash75 1993

[58] MHirai and A Kumar ldquoWavelength tuning of surface plasmonresonance by annealing silver-copper nanoparticlesrdquo Journal ofApplied Physics vol 100 no 1 Article ID 014309 2006

[59] S J Kim E A Stach and C A Handwerker ldquoFabrication ofconductive interconnects by Ag migration in Cu-Ag core-shellnanoparticlesrdquoApplied Physics Letters vol 96 no 14 Article ID144101 2010


[60] Y I Vesnin and Y V Shubin ldquoEquilibrium solid solubilities inthe Ag-Cu system by X-ray diffractometryrdquo Journal of Physics Fvol 18 no 11 pp 2381ndash2386 1988

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of



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NanoscienceJournal of

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Journal of

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Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research



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materials


Journal ofNanomaterials


Table 1 Synthesis parameters of SnAg nanoparticles

Sample C16H30O4Sn (g) AgNO3 (g) CH3CH2OH (mL) C12H8N2 sdotH2O (g) NaBH4 (g) Reaction time (min)SnAg1 02998 00051 60 02775 01892 15SnAg2 02998 00051 60 02775 01892 30SnAg3 02998 00051 60 02775 01892 45SnAg4 02998 00051 60 02775 01892 g 60

Table 2 Synthesis parameters of SAC nanoparticles

Sample C16H30O4Sn(g)

AgNO3(g)

Cu(OC2H5)2 sdotH2O(g)

CH3CH2OH(mL)

C12H8N2 sdotH2O(g)

NaBH4(g)

Reaction time(min)

SAC1 03293 00047 00017 60 02220 01892 15SAC2 03293 00047 00017 60 02220 01892 30SAC3 03293 00047 00017 60 02220 01892 45SAC4 03293 00047 00017 60 02220 01892 60

in an anhydrous ethanol solution during the reaction Manyexperimental parameters were considered to help explain thedifferences in the XRD patterns found in the literature

2 Experimental

The materials used to synthesize Sn35Ag nanoparticleswere tin(II) 2-ethylhexanoate (C

16H30O4Sn) and silver

nitrate (AgNO3) 110-phenanthroline (C

12H8N2sdotH2O)

sodium borohydride (NaBH4) and anhydrous ethanol

(CH3CH2OH) were selected as the surfactant reducing

agent and solvent respectively In terms of the synthesis ofSn30Ag05Cu (SAC) nanoparticles copper (II) ethoxidemonohydrate (Cu(OC

2H5)2sdotH2O) was added to the reactant

In a typical synthesis of Sn35Ag nanoparticles 02998 gof tin (II) 2-ethylhexanoate 00051 g of silver nitrate and02775 g of 110-phenanthroline were mixed with 60mL ofanhydrous ethanol to prepare the precursor solution Themixture was stirred for about 2 hours before 01892 g ofsodiumborohydridewas added into the stirring solutionThereaction timewas the variable to be tested in the experimentalprocedure so set reaction times of 15min 30min 45minand 60min were usedThe as-synthesized nanoparticles wereprecipitated by a centrifuge at a rate of 4000 rpm for 45minDue to the low solubility of NaBH

4in ethanol [22] the

reaction rate during the separation process was extremelylowThe reduction reaction could be stopped at any predeter-mined time through thismethodThe nanoparticles obtainedwere rinsed 3 times with anhydrous ethanol and then driedin the vacuum chamber at 40∘C for 8 hours The synthesisprocedure of Sn30Ag05Cu nanoparticles was similar to thatof Sn35Ag nanoparticles

The synthesis parameters of these two lead-free nanopar-ticles with different reaction times were listed in Tables 1 and2 respectively

The crystal structure of the synthesized SnAg alloynanoparticles was characterized by X-ray diffraction (XRD)from20∘ to 90∘ (2120579) usingCuK120572 radiation (120582= 0154056 nm)on a Rigaku DMax-2550 X-ray diffractometer The electron

accelerating voltage and accelerating current used in thedetection process were 40 kV and 200mA respectively

The SAC particle samples were measured on a RigakuDMax-2200 X-ray diffractometer from 20∘ to 90∘ (2120579) Thewavelength of the X-ray from the Cu K120572 radiation was0154056 nm The electron accelerating voltage and acceler-ating current used in the detection process were 40 kV and40mA respectively The surface features of the synthesizedparticles were studied by using a scanning electron micro-scope (SEM model JSM-6700F)

3 Results and Discussion

31 Formation Process of SnAg Nanoparticles Figure 1 showsthe XRD results of the synthesized SnAg nanoparticlesTherewere two clear phases the 120573-Sn and Ag

3Sn indicating the

successful alloying of Sn and Ag during the synthesis processThis was further confirmed through their crystal struc-tures by high resolution transmission electron microscopy(HRTEM) [23] The relative intensity of the diffraction peaksof 120573-Sn increased with the reaction time while the Ag

3Sn

phase showed the opposite trendThe relative intensity of the three strong peaks from the

Ag3Sn phase obtained from the XRD pattern was shown

in Figure 2 It was obvious that the relative intensity of thestrongest peak declined from 100 to 10 A similar trendcould be found in the other two strong peaks It tendedtowards stability when the reaction time increased from40min to 60min

The relative intensity of the diffraction peak of the Ag3Sn

phase indicted the formation process of the twophasesWhenthe reaction time was 15min the relative intensity of thediffraction peak of the Ag

3Sn phase was at the maximum

At the same time the diffraction peak of 120573-Sn phase couldalso be found as shown in Figure 1(a) This implied that theproduct was mainly in the Ag

3Sn phase When the reaction

time increased to 30min the relative intensity of the diffrac-tion peak of Ag

3Sn phase in the synthesized nanoparticles

decreased dramatically as shown in Figure 2 The maximum


Inte

nsity

(au

)

20 30 40 50 60 70 80 902120579 (deg)

SnAg115min

SnAg3Sn

998786

998786

998786 998786 998786998786998786

(a)

Inte

nsity

(au

)

20 30 40 50 60 70 80 902120579 (deg)

SnAg2 30min

(b)

Inte

nsity

(au

)

20 30 40 50 60 70 80 902120579 (deg)

SnAg3 45min

(c)

20 30 40 50 60 70 80 90In

tens

ity (a

u)

2120579 (deg)

SnAg4 60min

(d)


15 30 45 600

20

40

60

80

100


Reaction time (min)

119868(

)







4 AgNO

3 and Cu(NO

3)sdot25H

2O









Sn2+(aq) + 2Ag

+997888rarr Sn4+




4could reduce Ag+


Inte

nsity

(au

)

20 30 40 50 60 70 80 902120579 (deg)

SAC1 15min

Sn(2

00)

Sn(1

12)

Ag 3

Sn(2

11)

Cu6Sn5(3

14)

(a)

Inte

nsity

(au

)

20 30 40 50 60 70 80 902120579 (deg)

SAC2 30min

Sn(1

01)

Sn(2

20)

(b)

Inte

nsity

(au

)

20 30 40 50 60 70 80 902120579 (deg)

SAC3 45min

Sn(2

11)

Sn(3

01)

Sn(4

00)

Sn(4

20)

Sn(3

12)

Sn(4

31)

(c)

20 30 40 50 60 70 80 90

Inte

nsity

(au

)2120579 (deg)

SAC4 60min

Sn(3

21)

Sn(4

11)

(d)




3





4



2Ag+ + 2BH4


2+ B2H6

(2)Sn2+ + 2BH

4


2+ B2H6

(3)


Ag+ + e = Ag E0 = 0799V (4)

Sn2+ + 2e = Sn E0 = minus0140V (5)




4


Ag nucleus

Cu nucleus

Sn atom

Sn nucleus


nanoparticle

nanoparticle

Sn nanoparticle


Ag+ Sn2+Sn2+

Cu2+

Ag3Sn

Ag3Sn

Cu6Sn5

Cu6Sn5

BHminus4

BHminus4








3Sn Cu




3Sn and Cu




Cu2+ + 2BH4


2+ B2H6

(6)







3Sn andCu

6Sn5 could








3Sn and Cu



2Ag+ + 2BH4


2+ B2H6

(7)

Cu2+ + 2BH4


2+ B2H6

(8)

Sn2+ + 2BH4


2+ B2H6

(9)


3Sn + Sn

(unreacted) (10)





4 Conclusions


Acknowledgment


References














































































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




Inte

nsity

(au

)

20 30 40 50 60 70 80 902120579 (deg)

SnAg115min

SnAg3Sn

998786

998786

998786 998786 998786998786998786

(a)

Inte

nsity

(au

)

20 30 40 50 60 70 80 902120579 (deg)

SnAg2 30min

(b)

Inte

nsity

(au

)

20 30 40 50 60 70 80 902120579 (deg)

SnAg3 45min

(c)

20 30 40 50 60 70 80 90In

tens

ity (a

u)

2120579 (deg)

SnAg4 60min

(d)


15 30 45 600

20

40

60

80

100


Reaction time (min)

119868(

)







4 AgNO

3 and Cu(NO

3)sdot25H

2O









Sn2+(aq) + 2Ag

+997888rarr Sn4+




4could reduce Ag+


Inte

nsity

(au

)

20 30 40 50 60 70 80 902120579 (deg)

SAC1 15min

Sn(2

00)

Sn(1

12)

Ag 3

Sn(2

11)

Cu6Sn5(3

14)

(a)

Inte

nsity

(au

)

20 30 40 50 60 70 80 902120579 (deg)

SAC2 30min

Sn(1

01)

Sn(2

20)

(b)

Inte

nsity

(au

)

20 30 40 50 60 70 80 902120579 (deg)

SAC3 45min

Sn(2

11)

Sn(3

01)

Sn(4

00)

Sn(4

20)

Sn(3

12)

Sn(4

31)

(c)

20 30 40 50 60 70 80 90

Inte

nsity

(au

)2120579 (deg)

SAC4 60min

Sn(3

21)

Sn(4

11)

(d)




3





4



2Ag+ + 2BH4


2+ B2H6

(2)Sn2+ + 2BH

4


2+ B2H6

(3)


Ag+ + e = Ag E0 = 0799V (4)

Sn2+ + 2e = Sn E0 = minus0140V (5)




4


Ag nucleus

Cu nucleus

Sn atom

Sn nucleus


nanoparticle

nanoparticle

Sn nanoparticle


Ag+ Sn2+Sn2+

Cu2+

Ag3Sn

Ag3Sn

Cu6Sn5

Cu6Sn5

BHminus4

BHminus4








3Sn Cu




3Sn and Cu




Cu2+ + 2BH4


2+ B2H6

(6)







3Sn andCu

6Sn5 could








3Sn and Cu



2Ag+ + 2BH4


2+ B2H6

(7)

Cu2+ + 2BH4


2+ B2H6

(8)

Sn2+ + 2BH4


2+ B2H6

(9)


3Sn + Sn

(unreacted) (10)





4 Conclusions


Acknowledgment


References














































































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




Inte

nsity

(au

)

20 30 40 50 60 70 80 902120579 (deg)

SAC1 15min

Sn(2

00)

Sn(1

12)

Ag 3

Sn(2

11)

Cu6Sn5(3

14)

(a)

Inte

nsity

(au

)

20 30 40 50 60 70 80 902120579 (deg)

SAC2 30min

Sn(1

01)

Sn(2

20)

(b)

Inte

nsity

(au

)

20 30 40 50 60 70 80 902120579 (deg)

SAC3 45min

Sn(2

11)

Sn(3

01)

Sn(4

00)

Sn(4

20)

Sn(3

12)

Sn(4

31)

(c)

20 30 40 50 60 70 80 90

Inte

nsity

(au

)2120579 (deg)

SAC4 60min

Sn(3

21)

Sn(4

11)

(d)




3





4



2Ag+ + 2BH4


2+ B2H6

(2)Sn2+ + 2BH

4


2+ B2H6

(3)


Ag+ + e = Ag E0 = 0799V (4)

Sn2+ + 2e = Sn E0 = minus0140V (5)




4


Ag nucleus

Cu nucleus

Sn atom

Sn nucleus


nanoparticle

nanoparticle

Sn nanoparticle


Ag+ Sn2+Sn2+

Cu2+

Ag3Sn

Ag3Sn

Cu6Sn5

Cu6Sn5

BHminus4

BHminus4








3Sn Cu




3Sn and Cu




Cu2+ + 2BH4


2+ B2H6

(6)







3Sn andCu

6Sn5 could








3Sn and Cu



2Ag+ + 2BH4


2+ B2H6

(7)

Cu2+ + 2BH4


2+ B2H6

(8)

Sn2+ + 2BH4


2+ B2H6

(9)


3Sn + Sn

(unreacted) (10)





4 Conclusions


Acknowledgment


References














































































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




Ag nucleus

Cu nucleus

Sn atom

Sn nucleus


nanoparticle

nanoparticle

Sn nanoparticle


Ag+ Sn2+Sn2+

Cu2+

Ag3Sn

Ag3Sn

Cu6Sn5

Cu6Sn5

BHminus4

BHminus4








3Sn Cu




3Sn and Cu




Cu2+ + 2BH4


2+ B2H6

(6)







3Sn andCu

6Sn5 could








3Sn and Cu



2Ag+ + 2BH4


2+ B2H6

(7)

Cu2+ + 2BH4


2+ B2H6

(8)

Sn2+ + 2BH4


2+ B2H6

(9)


3Sn + Sn

(unreacted) (10)





4 Conclusions


Acknowledgment


References














































































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials







3Sn andCu

6Sn5 could








3Sn and Cu



2Ag+ + 2BH4


2+ B2H6

(7)

Cu2+ + 2BH4


2+ B2H6

(8)

Sn2+ + 2BH4


2+ B2H6

(9)


3Sn + Sn

(unreacted) (10)





4 Conclusions


Acknowledgment


References














































































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




4 Conclusions


Acknowledgment


References














































































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials






















































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



research article investigating the formation process of sn...

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