Superparamagnetic nickel nanoparticles obtained by an organometallic approach

RESEARCH PAPER

Superparamagnetic nickel nanoparticles obtainedby an organometallic approach

E. Ramırez-Meneses • I. Betancourt • F. Morales •

V. Montiel-Palma • C. C. Villanueva-Alvarado •

M. E. Hernandez-Rojas

Received: 16 February 2010 / Accepted: 16 July 2010 / Published online: 11 August 2010

� Springer Science+Business Media B.V. 2010

Abstract Nickel nanoparticles were prepared by

decomposition of the organometallic precursor

Ni(COD)2 (COD=cycloocta-1,5-diene) dissolved in

organic media in the presence of anthranilic acid as

stabilizer. Transmission electron microscopy revealed

nickel nanoparticles with a mean size of 4.2 ± 1.1 nm

and selected area electron diffraction showed the

formation of fcc nickel. FTIR spectroscopy confirmed

the presence of modified anthranilic acid on the

surface of the Ni nanoparticles suggesting that it is

able to interact with the metal particles. The magnetic

response of the nanoparticles was established as being

of superparmagnetic character, for which a detailed

quantitative analysis resulted in a mean magnetic

moment of 2652 lB per particle together with a

blocking temperature of 32 K.

Keywords Nanostructures � Chemical synthesis �Superparamagnetism � Magnetic properties �Synthesis

Introduction

Metallic nanoparticles have received considerable

attention due to the unique characteristics originated

from the quantum confinement effects attributable to

the reduction of band structure into discrete quantum

levels as a result of the limited size of the particles.

Size, shape, and surface state of metal nanoparticles

have interesting electronic, optical, magnetic, and

chemical properties, which are usually not observed

for their bulk counterparts (Schmid 1992). Thus,

nanoparticles have potential applications in various

fields such as microelectronics, optoelectronics, catal-

ysis, magnetic materials, and information storage,

among others (Pang et al. 2003; Duran Pachon et al.

2006; Rosenweig 1989; O’Grady et al. 1998; Wang

et al. 2002; Sun et al. 2000; Zabow et al. 2008), making

the research on the synthesis of metallic nanoparticles

of controlled size and shape a major thrust area today.

E. Ramırez-Meneses (&)

Departamento de Ingenierıa y Ciencias Quımicas,

Universidad Iberoamericana, Ciudad de Mexico,

Prolongacion Paseo de la Reforma 880,

Lomas de Santa Fe, C.P. 01219 Mexico, D.F., Mexico

e-mail: [email protected]

E. Ramırez-Meneses � C. C. Villanueva-Alvarado

Centro de Investigacion en Ciencia Aplicada y Tecnologıa

Avanzada-Instituto Politecnico Nacional, CICATA

Altamira, Km 14.5 Carretera Tampico - Puerto Industrial,

C.P. 89600 Altamira, Tamaulipas, Mexico

I. Betancourt � F. Morales � M. E. Hernandez-Rojas

Instituto de Investigaciones en Materiales, Universidad

Nacional Autonoma de Mexico, 04510 Mexico, D.F.,

Mexico

V. Montiel-Palma

Centro de Investigaciones Quımicas, Universidad

Autonoma del Estado de Morelos, Av. Universidad 1001,

Col. Chamilpa, C.P. 62209 Cuernavaca, Morelos, Mexico

123

J Nanopart Res (2011) 13:365–374

DOI 10.1007/s11051-010-0039-7

Specifically, magnetic nanoparticles have potential

applications in ultra-high magnetic storage devices,

ferrofluids, magnetic refrigeration systems, and mag-

netic carriers for drug targeting (Park et al. 2005;

Santini et al. 2005). In particular, the search for

synthetic routes aiming at obtaining nickel nanopar-

ticles with controllable mean size and narrow distri-

bution, as well as specific morphology, has elicited a

considerable interest because of the soft magnetic

character of Ni. In this sense, several physical and

chemical methods have been reported for the synthesis

of a variety of Ni nanostructures such as pyrolysis (Che

et al. 1999), sputtering (Thompson et al. 2002),

reversed micelles (Chen and Wu 2000; Mandal et al.

2003), aqueous and nonaqueous chemical reduction

(Wu and Chen 2004; Green and O’Brien 2001; Hou

and Gao 2003), sonochemical deposition (Ramesh

et al. 1997), polyol method (Kurihara et al. 1995;

Chakroune et al. 2003; Chow et al. 1999; Yin and

Chow 2002; Toneguzzo et al. 2000; Tzitzios et al.

2006), laser-driven thermal methods (He et al. 2005),

and an organometallic approach (Cordente et al. 2001;

Margeat et al. 2007) have been applied. The reduction

of NiCl2 using reducing agents such as hydrogen,

hydrazine (Xu et al. 2008; Zhang et al. 2005; Bai et al.

2008), and NaBH4 are the most common procedures to

prepare Ni nanoparticles. However, the use of boro-

hydrides to reduce nickel salts alters magnetic prop-

erties due to the formation of boron inclusions or of a

boron oxide surface layer (Petit et al. 1999; Schaefer

et al. 2008). In contrast, organometallic compounds

have been employed as alternative precursors in high

temperature decomposition processes such as chemi-

cal vapor deposition (Hyungsoo et al. 2003; Bahlaw-

ane et al. 2010) or decomposed in mild conditions,

generally using a reducing gas. This organometallic

approach involves the decomposition of an olefinic

complex of the desired metal in a low-valent state

under a dihydrogen atmosphere in organic medium at

mild conditions generating only alkanes as byprod-

ucts, which are not supposed to be adsorbed at the

surface of the particles under these conditions (Chaud-

ret 2005; Philippot and Chaudret 2007). Thus, reduc-

ing agents such as borohydrides and mineral salts are

excluded. Under these conditions, the process yield

metal nanoparticles with clean surface (Bradley et al.

1992; Duteil et al. 1993; De Caro and Bradley 1997;

Ely et al. 1999; Bradley et al. 2000; Cordente et al.

2001; Migowski et al. 2007).

An important aspect in the production of the

nanoparticles by chemical methods is the ability to

keep them physically isolated one from another

preventing irreversible agglomeration. The stability

of the nanoparticles is generally achieved by using

different protective molecules (ligands) to avoid their

agglomeration. In fact, parameters such as the propor-

tion of ligand coverage or the partial oxidation on the

surface of metal particles are not easily measured but

they are known to modify the catalytic activity or

magnetic behavior. In the case of nickel nanoparticles

synthesized from Ni(COD)2 (COD = cycloocta-1,5-

diene) in the presence of donor ligand hexadecyl-

amine, the latter species not only does not alter the

surface magnetism of the nanoparticles but promotes

an adequate shape control, generating nickel nanorods.

The magnetic properties of this system were evaluated

showing that its saturation magnetization is compara-

ble to that of bulk nickel (Cordente et al. 2001; Pick

and Dreysse 2000). It is well known that selective

coordination of a ligand on a facet of the produced

nanoparticles seems to be the key for an anisotropic

growth of nanoparticles (Puntes et al. 2001; Peng and

Peng 2001; Wang et al. 1998; Cordente et al. 2001).

Recently, oleylamine and trioctylphosphine have been

used to obtain monodispersed nickel nanoparticles

(2–30 nm) from Ni(acac)2 (acac = pentane-2,4-dio-

nate) by thermal decomposition (Carenco et al. 2010).

In this context, we wish to investigate the effect of the

stabilizer, anthranilic acid (AA), 2-(H2N)C6H4CO2H

on the shape and magnetic properties of nickel

nanoparticles obtained from the decomposition of

Ni(COD)2 as precursor under dihydrogen atmosphere

in organic medium. The skeleton and functional groups

of the stabilizer can interact with the surface and then

favor or not the growth of the particles in a preferential

direction as we have previously reported for the

synthesis of Pt nanoparticles from the Pt2(dba)3

precursor using hexadecylamine as stabilizer (Ramirez

et al. 2007). In that work, the important role of the

amine ligand in the nanostructure shape was demon-

strated. We have now selected AA among other

stabilizers due to its potential hemilability. Indeed,

either the carboxilate and/or the amino groups may

coordinate to the metal surface of the nanoparticles,

while the remaining functionality could act as an

additional but much weaker stabilizer. We anticipated

that under the reaction conditions AA would at

least partially ionize into the carboxylate/NH3?

366 J Nanopart Res (2011) 13:365–374

123

zwitterionic form and thus be able to interact with the

metal surface of nanoparticles via the two oxygen atoms

in a fashion which resembles carboxylate molecular

systems (Fig. 1). Additionally, the magnetic response

of the obtained stabilized nickel nanoparticles is

described in terms of a superparamagnetic model

including a realistic magnetic moment distribution.

Experimental techniques

All operations were carried out using standard Schlenk

tube or Fischer–Porter bottle techniques or in a

glove box under argon. Tetrahydrofurane 99.9%

(THF) and hexane were purified just before use by

distillation under a nitrogen atmosphere over sodium

benzophenone. Ni(COD)2 (COD=cycloocta-1,5-diene)

(99%, Aldrich) and AA, 2-(H2N)C6H4CO2H (99.5%,

Aldrich), H2 (99.99%, INFRA), and argon (99.99%,

INFRA) were used as-received.

Nickel nanosized particles were synthesized by an

organometallic approach (Fig. 1). Ni(COD)2 (0.05 g)

and AA (1 or 2 equivalents) were dissolved in THF

(40 mL) under argon atmosphere in a Fisher–Porter

bottle. AA was added in a molar ratio metal:stabilizer

1:2. Then, the mixture was pressurized under dihy-

drogen (3 bars) for 20 h and heated to 70 �C. During

this time, the mixture changed from being a transpar-

ent yellow solution to a dark brown colloidal solution

(Dominguez-Crespo et al. 2009; Bradley et al. 2000;

Cordente et al. 2001). The obtained colloidal solution

was then concentrated under vacuum. The brown

precipitate was then washed with hexane (3 9 20 mL)

to eliminate by-products. Finally, the concentrated

solution was dried under vacuum giving rise to a dark

powder.

The morphology and structure of the Ni nanopar-

ticles were verified by means of transmission electron

microscopy (TEM and HRTEM) analyses, which were

performed on a JEOL-2000 FX II electron microscope,

operating at 200 kV and JEOL JEM-2010F Field

Emission microscope, respectively. Each specimen for

TEM analysis was prepared in the glove box by slow

evaporation of a drop of each crude colloidal solution

deposited onto a holey carbon copper grid. Fourier

transform-infrared spectroscopy (FTIR, Spectrum One

Perkin Elmer Lambda 40) was used to determine the

presence and coordination of AA on the surface of the

Ni nanoparticles using KBr (Aldrich, 99% IR grade)

pellets after isolation of the product as solid. The

magnetic properties of the Ni nanoparticles were

determined in a Quantum Design SQUID magnetom-

eter (MPMS-5) with a maximum applied field H of

10,000 Oe. For magnetization M versus temperature

T measurements, the sample was cooled down to 2 K

without applied field, and after that, heated up and

measured under an external field of 200 Oe up to room

temperature (zero-field-cooled (ZFC) curve). A sub-

sequent cooling under the same external field intensity

allows the recording of the field-cooling (FC) curve.

Results

The TEM micrograph of the stabilized Ni nanoparti-

cles exhibits the presence of isolated and homoge-

nously dispersed, spherical units or small primary

particles (Fig. 2a), which are also evident by dark

field imaging as white spots in Fig. 2b. The corre-

sponding particle size histogram indicates a mean

particle size of 4.2 ± 1.1 nm (Fig. 2d). Some big

agglomerates of these particles are also observed.

These agglomerates can be regarded as secondary

structures, which are self-assemblies organized by

numerous smaller primary nanoparticles with

OHO

3 bar H2 , 70 oC- cyclooctene, - cyclooctane

H2N

NiO-

+H3N

O

O-

NH3+

O

OH2N OH

O- NH3+

O

stabilized Ni colloid

2

Fig. 1 Synthesis of

stabilized Ni nanoparticles

from Ni(COD)2 and

dihydrogen

J Nanopart Res (2011) 13:365–374 367

123

spherical shape. Similar structures have been previ-

ously observed (Xu et al. 2008). This type of

organization can be ascribed to the mutual attraction

of magnetic dipoles as mentioned by the authors. The

related selected area electron diffraction (SAED)

pattern shown in Fig. 2c verifies the formation of

fcc nickel, for which four fringe patterns with inter-

plane distances of 2.09, 1.75, 1.31, and 1.06 A can be

associated to the (111), (200), (220), and (311) planes,

respectively. HRTEM analysis confirm the presence

of monodisperse nickel nanoparticles of spherical

shape, Fig. 3. Figure 4 shows the comparative FTIR

spectra of commercial AA and the system of Ni

nanoparticles stabilized with the same product. We

anticipated that under the experimental conditions of

this work, AA could at least partially exist as a

zwitterionic species in which the carboxilate group

would be able to form via the two oxygen atoms either

four-member quelate-like or dinuclear bridging

species as has been previously informed in the

literature (Wiesbrock and Schmidbaur 2002). Indeed,

the spectrum of AA (Fig. 4a) exhibits the C=O

stretching vibration at 1663 cm-1, while in the case

of nickel nanoparticles stabilized by AA, this signal is

depleted. In contrast, the FTIR spectrum of the latter

shows vibrations at 1615 and 1596 cm-1, which could

be ascribed to the antisymmetric and symmetric,

respectively, COO- stretching vibrations of the carbo-

xylate group resulting from complexation (Borowski

and Rajca 1984, Fig. 4b). On the other hand, the

spectrum of commercial AA (Fig. 4a) shows a band at

1584 cm-1 ascribed to a NH2 bending vibration, but

after the formation of nanoparticles the FTIR shows

this vibrational mode shifted to 1540 cm-1. Finally,

the two sharp N–H stretching vibrations of AA at

3328 and 3241 cm-1 are replaced by weak m(N–H)

bands at 3308 and 3126 cm-1 and a weak broad band

at 3221 cm-1 possibly due to adsorbed water or lattice

Fig. 2 a TEM micrograph

of nickel nanoparticles

stabilized by anthranilic

acid, b dark field image,

c the corresponding SAED

pattern, and d particle size

distribution showing a mean

size of 4.2 ± 1.1 nm

368 J Nanopart Res (2011) 13:365–374

123

water (Nakamoto 1997). These findings are in agree-

ment with a certain degree of ionization and thus at

least partial zwitterionic formation in polar THF

(Fig. 1). In addition, the presence and shifts of the

N–H vibrations could also point out to the possible

coordination to the metal through both one of the

oxygen atoms of the carboxylic acid and the proton-

ated NH2 functionality (Fig. 1) as literature precedents

have informed (Branch et al. 2001). It is indeed highly

possible that at the experimental conditions both forms

of stabilization co-exist.

Concerning magnetic properties, Fig. 5 displays

the room temperature M–H curve for the Ni nano-

particles, for which an anhysteretic response is

manifested together with a maximum magnetisation

of 2.12 emu/g.

Fig. 3 HRTEM micrographs of nickel nanoparticles stabilized

by anthranilic acid

4000 3500 3000 2500 2000 1500 1000 500

3126

1615

3308

3221

1596

(b)Tran

smit

tan

ce (

a. u

.)

Waven number (cm-1)

1663

158432

4133

28

(a)

Fig. 4 Comparative FTIR of commercial AA (a) and nickel

nanoparticles stabilized by AA (b). The spectrum of the Ni/AA

system shows no bands in the 2000–3000 cm-1 region, unlike

the uncoordinated AA system

Fig. 5 Experimental M–H curve for nanosized Ni particles

measured at room temperature (full circles). Fitting of the

superparamagnetic model, Eqs. 3, 4, for T = 300 K (SolidLine. Fitting error: ±0.06 emu/g). Since the uncertainty of

SQUID magnetometers for magnetic moment measurement is

usually lower than 0.1%, the associated error bar associated

with each data point is much smaller than the data symbol size

and thus, unfeasible to be included

J Nanopart Res (2011) 13:365–374 369

123

Discussion

The use of AA as optional stabilizer in the organo-

metallic approach presented here has proved to be a

useful and efficient alternative to obtain homoge-

nously dispersed Ni nanoparticles with spherical

morphology. We identify two main differences

arising from the use of AA as stabilizer as compared

to the use of amines previously reported (Cordente

et al. 2001). The first is that in the present work no

rigid nanostructures were observed. We attribute this

to the lower ability to coordinate nickel of the oxygen

atoms with respect to the nitrogen atoms therefore

decreasing the possibilities of forming ordered sec-

ondary structures. The second big difference is that

for the amine-stabilized Ni nanoparticles (trioctyl-

phosphine oxide) complexation leads to reduced

magnetization in contrast with the present work.

Again we attribute this to the lower coordination

ability of oxygen with respect to nitrogen yet strong

enough for stabilizing Ni nanosystems.

For the present case, the absence of hysteresis

observed for the room temperature M–H curve can be

associated with a superparamagnetic behavior of the

ensemble, as it is evidenced by the M/Ms versus H/T

curves for decreasing temperatures T shown in Fig. 6,

for which all plots merge into a single curve across

the temperature interval for M–H measurement (Lu

et al. 2007). This particular magnetic response is

afforded on one hand, by the single-domain character

of the Ni particles, since the experimental mean

particle size of 4.2 ± 1.1 nm is clearly smaller than

the threshold diameter Dsd for the formation of

magnetically saturated particles (i.e., single-domain

entities) as it is explained in the following.

The Dsd can be estimated according to the

following expression (Kronmuller and Fahnle 2003):

Dcrit ¼72

4pM2s

ffiffiffiffiffiffiffiffiffi

AK1

p

ð1Þ

where Ms is the saturation magnetization, A the

exchange constant, and K1 the magnetocrystalline

anisotropy. For the case of pure fcc Ni, it corresponds

to Ms = 484.1 emu/cm3, A = 7.2 9 10-7 erg/cm,

and K1 = 4.5 9 104 erg/cm3 (Kronmuller and Fahnle

2003), and consequently, Dsd = 4.4 9 10-6 cm =

4.4 9 10-8 m = 44 9 10-9 m = 44 nm, well above

the mean size observed by TEM technique (Fig. 2).

On the other hand, for diminishing single-domain

particles, the corresponding spin coherent rotation

within each particle becomes thermally activated with

energy kBT/2 (kB = Boltzmann constant = 1.3806 9

10-16 erg/K) (Respaud et al. 1998), which becomes

comparable to the magnetic energy barrier K1Vc

(where Vc = critical particle volume) separating the

two possible equilibrium magnetization states for each

particle. Therefore, at a given temperature T the

critical particle volume Vc for superparamagnetic

response can be estimated from

kBT

2¼ KaVc ð2Þ

for which Vc = 4.60 9 10-19 cm3 at T = 300 K for

pure fcc Ni. Hence, the corresponding threshold

particle diameter Dsp for superparamagnetic response

of fcc Ni can be estimated by bearing in mind the

formula for the volume of a sphere of diameter

(V = pDsp3 /6) from which Dsp = (6Vc/p)1/3 = (6 9

4.60 9 10-19 cm3/p) = 9.57 9 10-7 cm = 9.57 nm,

which is clearly higher than the observed mean particle

size of 4.2 ± 1.1 nm, thus justifying the superpara-

magnetic behavior illustrated in Figs. 5 and 6.

A further detailed analysis of this magnetic

response was carried out by means of a model for

superparamagnetic particles, which considers a real-

istic magnetic moment l distribution f(l) (Ferrari

et al. 1997). According to this, the magnetization

Fig. 6 Superparamagnetic response of Ni nanoparticles at

variable temperature. Since the uncertainty of SQUID magne-

tometers for magnetic moment measurement is usually lower

than 0.1%, the associated error bar associated with each data

point is much smaller than the data symbol size and thus,

unfeasible to be included

370 J Nanopart Res (2011) 13:365–374

123

M as a function of the applied field H and temperature

T is given by

M H; Tð Þ ¼Z

1

0

l LlH

kBT

� �

f lð Þdl; ð3Þ

where L(lH/kBT) is the Langevin function:

LlH

kBT

� �

¼ cothlH

kBT

� �

� kBT

lHð4Þ

with f(l) a log-normal magnetic moment distribution

function given by

f lð Þ ¼ Nffiffiffiffiffiffi

2pp

r

1

lexp �

ln2 ll0

� �

2r2

0

@

1

A ð5Þ

where N is the number of particles per unit volume

and r, l0 are free parameters of the distribution. The

fitting of the superparamagnetic model with the

experimental data was carried out as follows: first, a

log-normal magnetic moment distribution is proposed

according to Eq. 5 with the following parameters:

l0 = 1450 and r = 1.10. Subsequently, the calcu-

lated magnetization M data were generated by means

of Eqs. 4 and 3 applied on varying H values from

10,000 to -10,000 Oe in steps of 200 Oe at a fixed

temperature T = 300 K. A direct comparison

between calculated and experimental data is shown

in Fig. 5, for which an excellent accord is observed.

In addition, the mean magnetic moment per

particle\l[can be calculated as (Ferrari et al. 1997)

Ms ¼Z

1

0

lf lð Þdl ¼ N\l[ : ð6Þ

By considering a magnetic moment distribution f(l)

with 50,000 values of l, the \l[ value for the Ni

nanoparticles according to Eq. 6 results of 2652 lB

(lB = Bohr magneton = 9.2740 9 10-21 erg/Oe).

By reminding MsNi = 484.1 emu/cm3, an associated

mean particle diameter of 4.58 nm can be estab-

lished. Remarkably, this calculated mean diameter

value coincides very well with the particle mean size

determined by TEM analysis (of 4.2 ± 1.1 nm).

Additionally, from the calculated mean radius

together with the Avogadro number and both, the

Ni atomic weight and Ni density, an estimation of the

number of Ni atoms per particle results in 4591 atom/

particle, from which the magnetic moment per Ni

atom, lNi, can be calculated as

lNi ¼ 2652lB=4591 atom ¼ 0:57lB=atom: ð7Þ

This value is in excellent agreement with the reported

magnetic moment for bulk fcc Ni (0.57–0.60 lB) (Lu

et al. 2007; Respaud et al. 1998). This result reflects

the null effect of the coordination between AA

molecules and Ni atoms on their electronic structure.

In general, previous reports on Ni nanoparticles

describe mean particle sizes[12 nm, with either hcp

or fcc structure and ferromagnetic response (Gong

et al. 2008; Chen and Wu 2000; Tzitzios et al. 2006;

Davar et al. 2009); few works (Gong et al. 2008;

Chen and Wu 2000; Hou and Gao 2003) mention

particles sizes below 10 nm with a shallow, non-

quantitative magnetic behavior characterization. The

relative importance of having very fine metallic

superparamagnetic entities depends basically on their

potential technological application. For instance,

these specific kinds of nanoparticles are very well

suited for magnetic resonance imaging (Hou and Gao

2003; Caravan et al. 1999).

In order to establish the blocking temperature TB

(which denotes the transition to the ‘‘blocked’’ state,

i.e., to the magnetic ordering) ZFC and FC measure-

ments were carried out from room temperature down to

2 K, as it is exhibited in Fig. 7, for which the maximum

in ZFC indicates a TB = 32 K. Below this tempera-

ture, an expected ferromagnetic response becomes

evident, as it is reflected in Fig. 8 for M–H measure-

ments at T \ 32 K. These low temperature M–H plots

does not show saturation at H = 10,000 Oe as a

consequence of an enlarged magnetocrystalline aniso-

tropy, which is characteristic of pure fcc Ni at low

temperatures. For instance, the anisotropy constant K1

for fcc Ni is of 1.2 9 106 erg/cm3 at T = 4 K

(Kronmuller and Fahnle 2003), which is considerable

higher than its room temperature (T = 300 K) value of

K1 = 4.5 9 104 erg/cm3 (Kronmuller and Fahnle

2003). This larger anisotropy constants determines

the large coercivity values observed of 218 and 348 Oe

for T = 20 and 10 K, respectively.

Conclusions

Nickel nanoparticles with mean size of 4.2 ± 1.1 nm

were successfully obtained from Ni(COD)2 precursor

J Nanopart Res (2011) 13:365–374 371

123

by using AA as organic stabilizer. FTIR evidences at

least partial AA zwitterionic formation in polar THF

(Fig. 1), which would result in metal stabilization via

the two oxygen atoms of the carboxylate moiety. In

addition, it is also possible that the non-ionized AA

molecules could also assist stabilization via coordi-

nation through the carbonylic oxygen atom and the

protonated NH2 functionality (Fig. 1). We believe

both forms of stabilization co-exist. The magnetic

response of the metal nanoparticles corresponds to a

superparamagnetic behavior, characterized by a

model with realistic grain size distribution, which

indicates a mean magnetic moment of 2652 lB per

particle. Further experimental measurements estab-

lished a blocking temperature of 32 K.

Acknowledgments We acknowledge financial support from

CONACyT through 59921, 105762, SIP-IPN 2008-0838, and

SIP-IPN 2009 projects and to Mr. Hector Dorantes Rosales

from ESIQIE-IPN for his valuable technical assistance for

TEM analysis.

References

Bahlawane N, Premkumar PA, Tian Z, Hong X, Qi F, Kohse-

Hoinghaus K (2010) Nickel and nickel-based nanoalloy

thin films from alcohol-assisted chemical vapor deposi-

tion. Chem Mater 22:92–100

Bai L, Yuan F, Tang Q (2008) Synthesis of nickel nanoparti-

cles with uniform size via a modified hydrazine reduction

route. Mater Lett 62:2267–2270

Borowski AF, Rajca I (1984) Structure and Properties of

Anthranilato- and N-henylanthranilatorhodium (I) Com-

plexes with cis-cycloocta-l, 5-diene. Trans Met Chem

9:109–112

Bradley JS, Hill EW, Behal S, Klein C, Chaudret B, Duteil A

(1992) Preparation and characterization of organosols of

monodispersed nanoscale palladium. Particle size effects

in the binding geometry of adsorbed carbon monoxide.

Chem Mater 4:1234–1239

Bradley JS, Tesche B, Busser W, Maase M, Reetz MTJ (2000)

Surface spectroscopic study of the stabilization mecha-

nism for shape-selectively synthesized nanostructured

transition metal colloids. Am Chem Soc 122:4631–4636

Branch CS, Lewinski J, Justyniak I, Bott SG, Lipkowski J,

Barron AR (2001) Aluminum and gallium compounds of

salicylic and anthranilic acids: examples of weak intra-

molecular hydrogen bonding. Dalton Trans 1253–1258

Caravan P, Ellison JJ, McMurry TJ, Lauffer RB (1999) Gad-

olinium(III) chelates as MRI contrast agents: structure,

dynamics, and applications. Chem Rev 99:2293–2352

Carenco S, Boissiere C, Nicole L, Sanchez C, Le Floch P,

Mezailles N (2010) Controlled design of tuneable mono-

disperse nickel nanoparticles. Chem Mater 22:1340–1349

Chakroune N, Viau G, Ricolleau C, Fievet-Vincent F, Fievet F

(2003) Cobalt-based anisotropic particles prepared by the

polyol process. J Mater Chem 13:312–318

Chaudret B (2005) Organometallic approach to nanoparticles

synthesis and self-organization. C R Phys 6:117–131

Che SL, Takada K, Takashima K, Sakurai O, Shinazaki K,

Mizutani N (1999) Preparation of dense spherical Ni

particles and hollow NiO particles by spray pyrolysis.

J Mater Sci 6:1313–1318

Chen DH, Wu SH (2000) Synthesis of nickel nanoparticles in

water-in-oil microemulsions. Chem Mater 12:1354–1360

Fig. 7 Magnetization as a function of temperature for Ni

nanoparticles measured in the ZFC and FC modes. Since the

uncertainty of SQUID magnetometers for magnetic moment

measurement is usually lower than 0.1%, the associated error

bar associated with each data point is much smaller than the

data symbol size and thus, unfeasible to be included

Fig. 8 M–H curves for the nanosized Ni particles measured at

T \ TB. Since the uncertainty of SQUID magnetometers for

magnetic moment measurement is usually lower than 0.1%, the

associated error bar associated with each data point is much

smaller than the data symbol size and thus, unfeasible to be

included

372 J Nanopart Res (2011) 13:365–374

123

Chow GM, Ding J, Zhang J, Lee KY, Surani D, Lawrence SH

(1999) Magnetic and hardness properties f nanostructured

Ni–C films deposited by a non-aqueous electroless

method. Appl Phys Lett 74:1889–1891

Cordente N, Respaud M, Senocq F, Casonove MJ, Amiens C,

Chaudret B (2001) Synthesis and magnetic properties of

nickel nanorods. Nano Lett 1:565–568

Davar F, Fereshteh Z, Salavati-Niasari M (2009) Nanoparticles

Ni and NiO: synthesis, characterization and magnetic

properties. J Alloy Compd 476:797–801

De Caro D, Bradley JS (1997) Surface spectroscopic study of

carbon monoxide adsorption on nanoscale nickel colloids

prepared from a zerovalent organometallic precursor.

Langmuir 13:3067–3069

Dominguez-Crespo MA, Ramırez-Meneses E, Montiel-Palma

V, Torres Huerta AM, Dorantes Rosales H (2009) Syn-

thesis and electrochemical characterization of stabilized

nickel nanoparticles. Int J Hydrogen Energy 34:1664–1676

Duran Pachon L, Thathagar MB, Hartl F, Rothenberg G (2006)

Palladium-coated nickel nanoclusters: new Hiyama cross-

coupling catalysts. Phys Chem Chem Phys 8:151–157

Duteil A, Queau R, Chaudret B, Mazel R, Roucau C, Bradley

JS (1993) Preparation of organic solutions or solid films of

small particles of ruthenium, palladium, and platinum

from organometallic precursors in the presence of cellu-

lose derivatives. Chem Mater 5:341–347

Ely TO, Amiens C, Chaudret B, Snoeck E, Verelst M, Respaud

M, Broto JM (1999) Synthesis of nickel nanoparticles.

Influence of aggregation induced by modification of

poly(vinylpyrrolidone) chain length on their magnetic

properties. Chem Mater 11:526–529

Ferrari EF, da Silva FCS, Knobel M (1997) Influence of the

distribution of magnetic moments on the magnetization

and magnetoresistance in granular alloys. Phys Rev B

56:6086–6093

Gong J, Wang LL, Liu Y, Yang JH, Zong ZG (2008) Structural

and magnetic properties of hcp and fcc Ni nanoparticles.

J Alloys Compd 457:6–9

Green M, O’Brien P (2001) The preparation of organically

functionalised chromium and nickel nanoparticles. Chem

Commun 1912–1913

He Y, Li X, Swihart MT (2005) Laser-driven aerosol synthesis

of nickel nanoparticles. Chem Mater 17:1017–1026

Hou Y, Gao S (2003) Monodisperse nickel nanoparticles pre-

pared from a monosurfactant system and their magnetic

properties. J Mater Chem 13:1510–1512

Hyungsoo C, Sungho P, Tae Hyung K (2003) Novel nickel

precursors for chemical vapor deposition. Chem Mater

15:3735–3738

Kronmuller H, Fahnle M (2003) Micromagnetism and the

microstructure of ferromagnetic solids. Cambridge Uni-

versity Press, Cambridge

Kurihara LK, Chow GM, Schoen PE (1995) Nanocrystalline

metallic powders and films produced by the polyol

method. Nanostruct Mater 5:607–613

Lu A-H, Salabas EL, Schuth F (2007) Magnetische Nanopar-

tikel: Synthese, Stabilisierung, Funktionalisierung und

Anwendung. Angew Chem 46:1242–1266

Mandal M, Kundu S, Sau TK, Yusuf SM, Pal T (2003) Syn-

thesis and characterization of superparamagnetic Ni–Pt

nanoalloy. Chem Mater 15:3710–3715

Margeat O, Ciuculescu D, Lecante P, Respaud M, Amiens C,

Chaudret B (2007) NiFe nanoparticles: a soft magnetic

material? Small 3:451–458

Migowski P, Machado G, Texeira SG, Alves MCM, Morais J,

Traverse A, Dupond J (2007) Synthesis and character-

ization of nickel nanoparticles dispersed in imidazolium

ionic liquids. Phys Chem Chem Phys 9:4814–4821

Nakamoto K (1997) Infrared and Raman spectra of inorganic

and coordination compounds, part B: applications in

coordination organometallic and bioinorganic chemistry,

5th edn. Wiley, New York

O’Grady K, White RL, Grundy PJ (1998) Whiter magnetic

recording. J Magn Mater 177:886–891

Pang T, Meng GW, Fang Q, Zhang LD (2003) Silver nanowire

array infrared polarizers. Nanotechnology 14:20–24

Park J, Kang E, Son SU, Park HM, Lee MK, Kim J, Kim KW,

Noh HJ, Park JH, Bae CJ, Park J-G, Hyeon T (2005)

Monodisperse nanoparticles of Ni and NiO: synthesis,

characterization, self-assembled superlattices, and cata-

lytic applications in the Suzuki coupling reaction. Adv

Mater 17:429–434

Peng ZA, Peng X (2001) Mechanisms of the shape evolution of

CdSe nanocrystals. J Am Chem Soc 123:1389–1395

Petit C, Taleb A, Pileni MP (1999) Cobalt nanosized particles

organized in a 2D superlattice: synthesis, characterization,

and magnetic properties. J Phys Chem B 103:1805–1810

Philippot K, Chaudret B (2007) Organometallic derived—I:

metals, colloids, and nanoparticle. In: Dermot O’Hare (vol

ed) Comprehensive organometallic chemistry III, vol 12.

Elsevier, Amsterdam, pp 71–99

Pick S, Dreysse H (2000) Tight-binding study of ammonia and

hydrogen adsorption on magnetic cobalt systems. Surf Sci

460:153–161

Puntes VF, Krishnan KM, Alivisatos AP (2001) Colloidal

nanocrystal shape and size control: the case of cobalt.

Science 291:2115–2117

Ramesh S, Koltypin Y, Prozorov R, Gedanken A (1997) So-

nochemical deposition and characterization of nanophasic

amorphous nickel on silica microspheres. Chem Mater

9:546–551

Ramirez E, Erades L, Philippot K, Lecante P, Chaudret B

(2007) Shape control of platinum nanoparticles. J Adv

Funct Mater 17:2219–2228

Respaud M, Broto JM, Rakoto H, Fert AR, Thomas L, Barbara

B, Verelst M, Snoeck E, Lecante P, Mosset A, Osuna J,

Ould Ely T, Amiens C, Chaudret B (1998) Surface effects

on the magnetic properties of ultrafine cobalt particles.

Phys Rev B 57:2925–2935

Rosenweig RE (1989) Magnetic fluids: phenomena and process

applications. Chem Eng Prog 85:53–61

Santini O, De Moraes AR, Mosca DH, De Souza PEN, De

Oliveira AJA, Marangoni R, Wypych F (2005) Structural

and magnetic properties of Fe and Co nanoparticles

embedded in powdered Al2O3. J Colloid Interface Sci

289:63–70

Schaefer ZL, Ke X, Schiffer P, Schaak RE (2008) Direct

solution synthesis, reaction pathway studies, and struc-

tural characterization of crystalline Ni3B nanoparticles.

J Phys Chem C 112:19846–19851

Schmid G (1992) Large clusters and colloids. Metals in the

embryonic state. Chem Rev 92:1709–1727

J Nanopart Res (2011) 13:365–374 373

123

Sun S, Murray CB, Weller D, Folks L, Moser A (2000)

Monodisperse FePt nanoparticles and ferromagnetic FePt

nanocrystal superlattices. Science 287:1989–1992

Thompson GB, Banerjee R, Zhang XD, Anderson PM, Fraser

HL (2002) Chemical ordering and texture in sputter-

deposited Ni3Al thin films. Acta Mater 50:643–651

Toneguzzo P, Viau G, Acher O, Guillet F, Bruneton E, Fievet-

Vincent F, Fievet F (2000) CoNi and FeCoNi fine parti-

cles prepared by the polyol process: physico-chemical

characterization and dynamic magnetic properties.

J Mater Sci 35:3767–3784

Tzitzios V, Basina G, Gjoka M, Alexandrakis V, Goergakilas

V, Niarchos D, Boukos N, Petridis D (2006) Chemical

synthesis and characterization of hcp Ni nanoparticles.

Nanotechnology 17:3750–3755

Wang ZL, Petrovski JM, Green TC, El-Sayed MA (1998)

Shape transformation and surface melting of cubic and

tetrahedral platinum nanocrystals. J Phys Chem B

102:6145–6151

Wang ZK, Kuok MH, Ng SC, Lockwood DJ, Cottam MG,

Nielsch K, Wehrspohn RB, Gosele U (2002) Spin-wave

quantization in ferromagnetic nickel nanowires. Phys Rev

Lett 89:27201

Wiesbrock F, Schmidbaur H (2002) The structural chemistry of

lithium, sodium and potassium anthranilate hydrates.

Dalton Trans 4703–4708

Wu SH, Chen DH (2004) Synthesis and stabilization of Ni

nanoparticles in a pure aqueous CTAB solution. Chem

Lett 33:406

Xu W, Liew KY, Liu H, Huang T, Sun C, Zhao Y (2008)

Microwave-assisted synthesis of nickel nanoparticles.

Mater Lett 62:2571–2573

Yin H, Chow GM (2002) Anomalous electroless polyol

deposition of FeNi powders and films. J Electrochem Soc

149:C68

Zabow G, Dodd S, Moreland J, Korestky A (2008) Micro-

engineered local field control for high-sensitivity multi-

spectral MRI. Nature 453:1058–1063

Zhang DE, Ni XM, Zhang HG, Li Y, Zhang XJ, Yang ZP

(2005) Synthesis of needle-like nickel nanoparticles in

water-in-oil microemulsion. Mater Lett 59:2011–2014

374 J Nanopart Res (2011) 13:365–374

123