In this study, amorphous iron-boron alloy nanoparticles successfully synthesized by mechanochemical 
method. The raw materials were ferrous sulfate heptahydrate (FeSO4.7H2O) as a source of iron and sodium 
borohydride (NaBH4) as a reducing agent. Powders grinding was performed with different 
NaBH4/FeSO4.7H2O molar ratio. The results revealed that high active and completely amorphous particles 
could be synthesized with the molar ratio of 4:1 for NaBH4:FeSO4 in 10 minutes of grinding time. Various 
characterizations, such as the chemical analysis, atomic absorption spectroscopy (AAS), fourier transform 
infrared spectroscopy (FT-IR), x-ray diffraction (XRD) and field emission scanning electron microscopy 
(FESEM) have been performed. The XRD results confirmed the formation of the amorphous phase. Other 
results also indicate the formation of amorphous alloy nanoparticles with an average particle size below 50 
nm and the composition was Fe-10 Wt 	
percent B.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3489

Sarraf-Mamoory, R.

Shajari, S.

Electronic Sumy State University Institutional Repository

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE NANOMATERIALS: APPLICATIONS AND PROPERTIES Vol. 1 No 1, 01PCN25(3pp) (2012)   2304-1862/2012/1(1)01PCN25(3) 01PCN25-1  2012 Tarbiat Modares University The Effect of Raw Materials Molar Ratio in Mechanochemical Synthesis of  Amorphous Fe-B Alloy Nanoparticles   S. Shajari*, R. Sarraf-Mamoory†  Tarbiat Modares University, Tehran, Iran  (Received 19 June 2012; published online 24 August 2012)  In this study, amorphous iron-boron alloy nanoparticles successfully synthesized by mechanochemical method. The raw materials were ferrous sulfate heptahydrate (FeSO4.7H2O) as a source of iron and sodium borohydride (NaBH4) as a reducing agent. Powders grinding was performed with different NaBH4/FeSO4.7H2O molar ratio. The results revealed that high active and completely amorphous particles could be synthesized with the molar ratio of 4:1 for NaBH4:FeSO4 in 10 minutes of grinding time. Various characterizations, such as the chemical analysis, atomic absorption spectroscopy (AAS), fourier transform infrared spectroscopy (FT-IR), x-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) have been performed. The XRD results confirmed the formation of the amorphous phase. Other results also indicate the formation of amorphous alloy nanoparticles with an average particle size below 50 nm and the composition was Fe-10 Wt  B.  Keywords: Amorphous, Nanoparticles, Fe-B alloys, Mechanochemical, NaBH4, Grinding.   PACS numbers: 61.46.Df, 61.05.cp                                                             *saber.shajari@modares.ac.ir † rsarrafm@modares.ac.ir 1. INTRODUCTION  Amorphous alloys as important materials were used due to mechanical properties, corrosion resistance, magnetic and catalytic behavior. Among these amorph-ous alloys materials, the iron-boron alloy is known due to soft magnetic properties [1-2]. This alloy usually pro-duced by the melt-spinning method, which produce amorphous thin ribbon at high temperatures and rapid cooling [3-4]. Both mechanical alloying and chemical reduction methods have been studied to produce amorphous Fe-B alloy nanoparticles [5-6]. The mechanical alloying method was reported to produce amorphous phase after many hours high energy ball grinding of pure iron and boron powders as raw materials [6]. The formation of amorphous alloy nanoparticles of Fe-B was studied by reduction of Fe2+ ions with BH4- ions in the iron salt and potassium borohydride aqueous solution. A series of studies on reduction technique have been revealed that reaction conditions, such as concentration , ratio of the reactants, pH value of the solution, mixing proce-dures and reaction temperatures, etc., have signif-icant effects on the composition and structure of amorp-hous nanoparticles [7-10]. Although, the above methods were used to produce amorphous alloys, the mechanochemical method is a simple solid-state reaction technique for the synthesis of nanoparticles [11]. In this method, the desired phase and particle size will be achieved by changing parame-ters such as type of mill, grinding time, ball to powder ratio and molar ratio of raw materials. This process is carried out in one step at low temperature [12-13]. Zhou et al. [11] were prepared Fe-based amorp-hous alloy nanoparticles by solid state reaction method at room temperature using powders of iron chloride and chromium chloride with potassium borohydride as raw material. In this study, the amorphous iron-boron alloy nanoparticles have been synthesized with difference molar ratios of iron sulfate hydrated and sodium boro-hydride which are new raw materials for this approach.  2. EXPERIMENTAL PROCEDURES  All the chemical materials used in the experiments were analytical reagent grades. The used raw materials were FeSO4·7H2O (99.98 , Merck), and NaBH4 (99 , Merck). The mol ratio of FeSO4: NaBH4 are listed in Table 1. The FeSO4.and NaBH4 mixtures powders were placed in an agate mortar and were grinded carefully at room temperature for 10 min. Since the reaction is associated with gas release, the milling is dangerous in a closed vial. After grinding, the mixture color changed from white to black. This indicated that the reaction has been occurred.   Table 1 – Raw materials were used for the preparation of Fe-B amorphous alloy.  Sample NaBH4 (mg) FeSO4 (mg) Molar ratio NaBH4: FeSO4 S1 0.67 2.48 2:1 S2 1.34 2.48 4:1 S3 2.02 2.48 6:1  The black product was moved to a glass beaker as soon as possible. At first, the product was washed care-fully with a large amount of deionized water for several times to remove residual ions from the reaction mix-ture, followed by washing with acetone to remove the water, and then collected by a centrifugation sytem. The acetone wet slurry on crucible was transferred to a box with slow flow of high purity argon gas (less than 100 ppm of oxygen) and maintained for 4 h to dry the sample and passivate the surface of the particles. Lack of passivation will lead to pyrophoric samples. The final product is fine black particles.  S. SHAJARI, R. SARRAF-MAMOORY PROC. NAP 1, 01PCN25 (2012)   01PCN25-2 The composition of the product was determined by the atomic absorption spectroscopy (AAS; Varian-Spect-rum AA220). The vibrations of atoms in the region from 400 to 4000 cm − 1 of the resultant were measured by a Fourier transformation infrared spectroscopy (FTIR; Perkin Elmer-Spectrum Frontier) and the potassium bromide disk technique. The phase study in samples was characterized by X-ray powder diffraction (XRD; Xpert-Philips) analysis with Cu Kα radiation. The mop-hology and particle sizes of the product were also stud-ied by a field emission scanning electron microsc-opy (FE-SEM; Hitachi) system equipped with an energy dispersive X-ray (EDX) spectrometer for the elemental analysis of the amorphous alloy nanoparticles.  3. RESULTS AND DISCUSSION  The observations showed that black powder was formed from white raw materials after grinding. This indicates that the reaction has occurred. Based on the reaction of ferrous sulfate heptahydrate and sodium bo-rohy-dride, the following equations has been occurred and the colorless released gas during the grinding was H2.    FeSO4  NaBH4  2Fe  HBO2  HNaSO4  2H2 (1)   NaBH4  H2O  B  NaOH  2.5H2 (2)  Black particles sticking to the magnet, during wash-ing the powders with electromagnetic stirrer, revealed that the particles are magnetic. Also, the formation of yellow fine particles on beaker wall was observed dur-ing washing process which indicate the oxidation of the particles.  The results of atomic absorption spectrometry (AAS) are shown in Table (2). Analysis shows that the particles have an average of 90  iron and 4  boron. The total amount of iron and boron is about 94 . As mentioned above, amorphous iron-boron alloy nanopa-ticles could be oxidized easily with oxygen in the air. Therefore, another most possible element except for iron and boron in the poroduct, could be oxygen. In this case, the content of the oxygen in the nanoparticles might be about 6  which might present on the surface of iron-boron particles. Also the results show that with increasing the molar ratio of NaBH4/FeSO4.7H2O, the amount of boron in the alloy composition is increased.  Table2– Results of atomic absorption spectroscopy.  Sample B (wt  Fe (wt  S1 3.3 90 S2 4.1 89.9 S3 6 88  Fig. 1 shows the X-ray diffraction pattern of S1, S2 and S3. As can be seen, there is no diffraction peak in the S2 and S3 samples, so that the S2 and S3 products are amorphous compounds. Only a broad peak at 46o angle can be seen. This is very close to the characteris-tic diffraction peak of α-iron crystal at 45o degrees for (110) plane. It indicates that the product is mainly composed of large amounts of iron. The small peak at 35  angle in the S3 diffraction pattern is very close to the characteristic diffraction peak (200) from Fe2B. This indicates that the product is mainly composed of large amount of Fe and small amount of Fe2B. It can be noted that the presence of boron in the iron lattice has helped to form amorphous Fe-B alloys. The broad peak shifts in S3 from 45  to 46  is probably due to the pres-ence of boron in iron lattice. In other words, it is well known that any increasing of boron content in com-pound can increase the possibility  of amorphous phase formation. In compliance with the AAS and XRD re-sults, increasing in molar ratio of NaBH4/FeSO4.7H2O from 2 to 4, increase the amount of boron in alloy com-position and amorphous phase formation but then de-crease it. Thus, it is not necessary to use a molar ratio much higher than 4 as adopted in some literature [11]. The optimal and suitable value for the preparation of amorphous Fe-B alloy nanoparticles can be considered to select 4 for molar ratio of NaBH4/FeSO4.7H2O.    Fig. 1 – X-ray diffraction for crystalline iron S1, S2 and S3 amorphous Fe-B alloy nanoparticles  The FESEM images in Fig. 2 show the morphology and particle size of amorphous Fe-B alloy nanopart-icles. As the images show, the particles have spherical shape with the average size of less than 100 nm. High surface energy and high activity of thermodynamically unstable amorphous nanoparticles lead to agglomerat-ion of iron-boron nanoparticles. In the higher resolution images of the nanoparticles, it could be seen that the particles size is below 50 nm in the great separation of agglomerated particles.    Fig. 2 – The FESEM micrographs of amorphous Fe-B alloy nanoparticles  Fig. 3 shows the Energy Dispersive X-ray analysis of  the images for S2 sample. It has a good agreement with the composition analysis results of the product by atomic absorption spectroscopy.   THE EFFECT OF RAW MATERIALS… PROC. NAP 1, 01PCN25 (2012)   01PCN25-3   Fig. 3 – The EDX analysis for S2 sample  Formation of amorphous iron-boron alloy nanoparti-cles by mechanochemical method through the grinding of ferrous sulfate heptahydrate and sodium borohydri-de is due to thermodynamically instability of NaBH4 and it has a great affinity for reduction. Therefore, the NaBH4 can react with the FeSO4.7H2O as easily as possible.  The infrared spectrum in Fig. 4 demonstrates four shoulders at around 668.99, 1456.44 and 2359.23, 3851.80 cm − 1. Generally, the transmittance peaks from the vibration of the metal–metal bond are in the region (  400 cm − 1) of the far-infrared spectra [11]. Therefore, the peak at 668.99 cm – 1 in the infrared spectra may be assigned to the stretching vibration of the Fe–B bond in the product. It can be concluded that iron and boron atoms are willing to form the alloy. Higher peak is re-lated to the hydrocarbon and water vapor in the air that has been recorded.    Fig. 4 – The FTIR spectrum of amorphous Fe-B (C, O, H) alloy nanoparticles  It should be noted that the mechanochemical reac-tions, during grinding at room temperature, is mainly a surface reaction. The reaction occurs only on the inter-face layers between the molecules or ions of the parti-cles of FeSO4.7H2O and NaBH4 powders. After the re-action on the surface, the product will be peeled off right away from the surface of the particles of the hy-drated iron sulfate powders due to the grinding of the reacting powders. Hence, the primary product consists of some atomic clusters. Unlike the high temperature solid state reaction, the structural arrangement or crystallization in the atomic clusters of the product are rather slow at room temperature. Perhaps, this is just why the amorphous iron boron alloy nanoparticles can thus be obtained very easily by mechanochemical method at room temperature. Although the above product contains some iron ox-ides due to the oxidation of the iron boron alloy parti-cles, the oxidation of the fresh iron boron alloy nano-particles can be avoided in the preparation process by using the inert gas atmosphere.   4. CONCLUSIONS  Mechanochemical method is a convenient and prac-tical way for synthesis of amorphous Fe-B alloy nano-particles. Amorphous Fe-B alloy nanoparticles can very easily be prepared through the reaction of ferrous sul-fate heptahydrate and sodium borohydride powders. By increasing the molar ratio of NaBH4/FeSO4.7H2O, the amount of boron in the alloy composition was increased and the amorphous phase formation was more favora-ble. The optimal and suitable molar ratio of NaBH4/FeSO4.7H2O for the preparation of amorphous Fe-B alloy nanoparticles is 4. The results of various characterizations indicate that the product is mainly amorphous Fe-B alloy nanoparticles with a diameter below 50 nm and contains fine iron oxides nanoparticl-es due to the surface oxidation.     REFERENCES  1. Y. Chen, Catalysis Today 44, 3 (1998). 2. J. Balogh, L. Bujdoso, T. Kemeny, I. Vincze, J. Phys.: Con-dens. Matter 9, L503 (1997). 3. W.H. Wang, C. Dong, C.H. Shek, Mater. Sci. Eng. R44, 45 (2004). 4. R. Babilas, R. Nowosielski, Arch. Mater. Sci. Eng. 44, 5 (2010). 5. H. Habazaki, Shreir's Corrosion 3, 2192 (2009). 6. J. Abenojar, F. Velasco, J.M. Mota, M.A. Martinez, J. Sol. State Chem. 177, 382 (2004). 7. J. Saida, Mater. Sci. Eng. A 179-180, 577 (1994). 8. J. Jiang, I. Dezsi, U. Gonser, X. Lin, J. Non-Cryst. Solids 124, 139 (1990). 9. S. Linderoth, S. Morup, et al. J. Appl. Phys. 67, 4472 (1990). 10. S. Rivas, M.A. Lopez Quintela, M.G. Bonome, R.J. Duro , J.M. Greneche, J. Magn. Magn. Mater. 122, 1-5 (1993). 11. M.L. Liu, H.L. Zhou, Y.R. Chen, Y.Q. Jia, Mater. Chem. Phys. 89, 289 (2005). 12. G.Q. Zhong, H.L. Zhou, Y.Q. Jia, J. Alloys Compd. 465, L1 (2008). 13. G.Q. Zhong, Q. Zhong, H.L. Zhou,Y.Q. Jia, Adv. Mater. Res. 236-238, 1717(2011). 14. R. Wannemacher, A. Pack, and M. Quinten, Appl. Phys. B 68, 225 (1999).   

The Effect of Raw Materials Molar Ratio in Mechanochemical Synthesis of  Amorphous Fe-B Alloy Nanoparticles

SocioEconomic Challenges Journal (Sumy State University)

PROCEEDINGS OF THE INTERNATIONAL CONFERENCE NANOMATERIALS: APPLICATIONS AND PROPERTIES 
Vol. 1 No 1, 01PCN25(3pp) (2012) 
 
 
2304-1862/2012/1(1)01PCN25(3) 01PCN25-1  2012 Tarbiat Modares University 
The Effect of Raw Materials Molar Ratio in Mechanochemical Synthesis of  
Amorphous Fe-B Alloy Nanoparticles  
 
S. Shajari*, R. Sarraf-Mamoory† 
 
Tarbiat Modares University, Tehran, Iran 
 
(Received 19 June 2012; published online 24 August 2012) 
 
In this study, amorphous iron-boron alloy nanoparticles successfully synthesized by mechanochemical 
method. The raw materials were ferrous sulfate heptahydrate (FeSO4.7H2O) as a source of iron and sodium 
borohydride (NaBH4) as a reducing agent. Powders grinding was performed with different 
NaBH4/FeSO4.7H2O molar ratio. The results revealed that high active and completely amorphous particles 
could be synthesized with the molar ratio of 4:1 for NaBH4:FeSO4 in 10 minutes of grinding time. Various 
characterizations, such as the chemical analysis, atomic absorption spectroscopy (AAS), fourier transform 
infrared spectroscopy (FT-IR), x-ray diffraction (XRD) and field emission scanning electron microscopy 
(FESEM) have been performed. The XRD results confirmed the formation of the amorphous phase. Other 
results also indicate the formation of amorphous alloy nanoparticles with an average particle size below 50 
nm and the composition was Fe-10 Wt  B. 
 
Keywords: Amorphous, Nanoparticles, Fe-B alloys, Mechanochemical, NaBH4, Grinding. 
 
 PACS numbers: 61.46.Df, 61.05.cp 
 
 
                                                          
*saber.shajari@modares.ac.ir 
† rsarrafm@modares.ac.ir 
1. INTRODUCTION 
 
Amorphous alloys as important materials were used 
due to mechanical properties, corrosion resistance, 
magnetic and catalytic behavior. Among these amorph-
ous alloys materials, the iron-boron alloy is known due 
to soft magnetic properties [1-2]. This alloy usually pro-
duced by the melt-spinning method, which produce 
amorphous thin ribbon at high temperatures and rapid 
cooling [3-4]. 
Both mechanical alloying and chemical reduction 
methods have been studied to produce amorphous Fe-B 
alloy nanoparticles [5-6]. The mechanical alloying 
method was reported to produce amorphous phase after 
many hours high energy ball grinding of pure iron and 
boron powders as raw materials [6]. The formation of 
amorphous alloy nanoparticles of Fe-B was studied by 
reduction of Fe2+ ions with BH4- ions in the iron salt 
and potassium borohydride aqueous solution. A series 
of studies on reduction technique have been revealed 
that reaction conditions, such as concentration , ratio of 
the reactants, pH value of the solution, mixing proce-
dures and reaction temperatures, etc., have signif-icant 
effects on the composition and structure of amorp-hous 
nanoparticles [7-10]. 
Although, the above methods were used to produce 
amorphous alloys, the mechanochemical method is a 
simple solid-state reaction technique for the synthesis 
of nanoparticles [11]. In this method, the desired phase 
and particle size will be achieved by changing parame-
ters such as type of mill, grinding time, ball to powder 
ratio and molar ratio of raw materials. This process is 
carried out in one step at low temperature [12-13]. 
Zhou et al. [11] were prepared Fe-based amorp-hous 
alloy nanoparticles by solid state reaction method at 
room temperature using powders of iron chloride and 
chromium chloride with potassium borohydride as raw 
material. In this study, the amorphous iron-boron alloy 
nanoparticles have been synthesized with difference 
molar ratios of iron sulfate hydrated and sodium boro-
hydride which are new raw materials for this approach. 
 
2. EXPERIMENTAL PROCEDURES 
 
All the chemical materials used in the experiments 
were analytical reagent grades. The used raw materials 
were FeSO4·7H2O (99.98 , Merck), and NaBH4 (99 , 
Merck). The mol ratio of FeSO4: NaBH4 are listed in 
Table 1. The FeSO4.and NaBH4 mixtures powders were 
placed in an agate mortar and were grinded carefully 
at room temperature for 10 min. Since the reaction is 
associated with gas release, the milling is dangerous in 
a closed vial. After grinding, the mixture color changed 
from white to black. This indicated that the reaction 
has been occurred.  
 
Table 1 – Raw materials were used for the preparation of Fe-
B amorphous alloy. 
 
Sample NaBH4 
(mg) 
FeSO4 (mg) Molar ratio 
NaBH4: FeSO4 
S1 0.67 2.48 2:1 
S2 1.34 2.48 4:1 
S3 2.02 2.48 6:1 
 
The black product was moved to a glass beaker as 
soon as possible. At first, the product was washed care-
fully with a large amount of deionized water for several 
times to remove residual ions from the reaction mix-
ture, followed by washing with acetone to remove the 
water, and then collected by a centrifugation sytem. 
The acetone wet slurry on crucible was transferred to a 
box with slow flow of high purity argon gas (less than 
100 ppm of oxygen) and maintained for 4 h to dry the 
sample and passivate the surface of the particles. Lack 
of passivation will lead to pyrophoric samples. The final 
product is fine black particles. 
 S. SHAJARI, R. SARRAF-MAMOORY PROC. NAP 1, 01PCN25 (2012) 
 
 
01PCN25-2 
The composition of the product was determined by 
the atomic absorption spectroscopy (AAS; Varian-Spect-
rum AA220). The vibrations of atoms in the region from 
400 to 4000 cm − 1 of the resultant were measured by a 
Fourier transformation infrared spectroscopy (FTIR; 
Perkin Elmer-Spectrum Frontier) and the potassium 
bromide disk technique. The phase study in samples 
was characterized by X-ray powder diffraction (XRD; 
Xpert-Philips) analysis with Cu Kα radiation. The mop-
hology and particle sizes of the product were also stud-
ied by a field emission scanning electron microsc-opy 
(FE-SEM; Hitachi) system equipped with an energy 
dispersive X-ray (EDX) spectrometer for the elemental 
analysis of the amorphous alloy nanoparticles. 
 
3. RESULTS AND DISCUSSION 
 
The observations showed that black powder was 
formed from white raw materials after grinding. This 
indicates that the reaction has occurred. Based on the 
reaction of ferrous sulfate heptahydrate and sodium bo-
rohy-dride, the following equations has been occurred and 
the colorless released gas during the grinding was H2.  
 
 FeSO4  NaBH4  2Fe  HBO2  HNaSO4  2H2 (1) 
 
 NaBH4  H2O  B  NaOH  2.5H2 (2) 
 
Black particles sticking to the magnet, during wash-
ing the powders with electromagnetic stirrer, revealed 
that the particles are magnetic. Also, the formation of 
yellow fine particles on beaker wall was observed dur-
ing washing process which indicate the oxidation of the 
particles.  
The results of atomic absorption spectrometry 
(AAS) are shown in Table (2). Analysis shows that the 
particles have an average of 90  iron and 4  boron. 
The total amount of iron and boron is about 94 . As 
mentioned above, amorphous iron-boron alloy nanopa-
ticles could be oxidized easily with oxygen in the air. 
Therefore, another most possible element except for 
iron and boron in the poroduct, could be oxygen. In this 
case, the content of the oxygen in the nanoparticles 
might be about 6  which might present on the surface 
of iron-boron particles. Also the results show that with 
increasing the molar ratio of NaBH4/FeSO4.7H2O, the 
amount of boron in the alloy composition is increased. 
 
Table2– Results of atomic absorption spectroscopy. 
 
Sample B (wt  Fe (wt  
S1 3.3 90 
S2 4.1 89.9 
S3 6 88 
 
Fig. 1 shows the X-ray diffraction pattern of S1, S2 
and S3. As can be seen, there is no diffraction peak in 
the S2 and S3 samples, so that the S2 and S3 products 
are amorphous compounds. Only a broad peak at 46o 
angle can be seen. This is very close to the characteris-
tic diffraction peak of α-iron crystal at 45o degrees for 
(110) plane. It indicates that the product is mainly 
composed of large amounts of iron. The small peak at 
35  angle in the S3 diffraction pattern is very close to 
the characteristic diffraction peak (200) from Fe2B. 
This indicates that the product is mainly composed of 
large amount of Fe and small amount of Fe2B. It can be 
noted that the presence of boron in the iron lattice has 
helped to form amorphous Fe-B alloys. The broad peak 
shifts in S3 from 45  to 46  is probably due to the pres-
ence of boron in iron lattice. In other words, it is well 
known that any increasing of boron content in com-
pound can increase the possibility  of amorphous phase 
formation. In compliance with the AAS and XRD re-
sults, increasing in molar ratio of NaBH4/FeSO4.7H2O 
from 2 to 4, increase the amount of boron in alloy com-
position and amorphous phase formation but then de-
crease it. Thus, it is not necessary to use a molar ratio 
much higher than 4 as adopted in some literature [11]. 
The optimal and suitable value for the preparation of 
amorphous Fe-B alloy nanoparticles can be considered 
to select 4 for molar ratio of NaBH4/FeSO4.7H2O. 
 
 
 
Fig. 1 – X-ray diffraction for crystalline iron S1, S2 and S3 
amorphous Fe-B alloy nanoparticles 
 
The FESEM images in Fig. 2 show the morphology 
and particle size of amorphous Fe-B alloy nanopart-
icles. As the images show, the particles have spherical 
shape with the average size of less than 100 nm. High 
surface energy and high activity of thermodynamically 
unstable amorphous nanoparticles lead to agglomerat-
ion of iron-boron nanoparticles. In the higher resolution 
images of the nanoparticles, it could be seen that the 
particles size is below 50 nm in the great separation of 
agglomerated particles. 
 
 
 
Fig. 2 – The FESEM micrographs of amorphous Fe-B alloy 
nanoparticles 
 
Fig. 3 shows the Energy Dispersive X-ray analysis 
of  the images for S2 sample. It has a good agreement 
with the composition analysis results of the product by 
atomic absorption spectroscopy. 
 
 THE EFFECT OF RAW MATERIALS… PROC. NAP 1, 01PCN25 (2012) 
 
 
01PCN25-3 
 
 
Fig. 3 – The EDX analysis for S2 sample 
 
Formation of amorphous iron-boron alloy nanoparti-
cles by mechanochemical method through the grinding of 
ferrous sulfate heptahydrate and sodium borohydri-de is 
due to thermodynamically instability of NaBH4 and it 
has a great affinity for reduction. Therefore, the NaBH4 
can react with the FeSO4.7H2O as easily as possible.  
The infrared spectrum in Fig. 4 demonstrates four 
shoulders at around 668.99, 1456.44 and 2359.23, 
3851.80 cm − 1. Generally, the transmittance peaks from 
the vibration of the metal–metal bond are in the region 
(  400 cm − 1) of the far-infrared spectra [11]. Therefore, 
the peak at 668.99 cm – 1 in the infrared spectra may be 
assigned to the stretching vibration of the Fe–B bond in 
the product. It can be concluded that iron and boron 
atoms are willing to form the alloy. Higher peak is re-
lated to the hydrocarbon and water vapor in the air 
that has been recorded. 
 
 
 
Fig. 4 – The FTIR spectrum of amorphous Fe-B (C, O, H) alloy 
nanoparticles 
 
It should be noted that the mechanochemical reac-
tions, during grinding at room temperature, is mainly a 
surface reaction. The reaction occurs only on the inter-
face layers between the molecules or ions of the parti-
cles of FeSO4.7H2O and NaBH4 powders. After the re-
action on the surface, the product will be peeled off 
right away from the surface of the particles of the hy-
drated iron sulfate powders due to the grinding of the 
reacting powders. Hence, the primary product consists 
of some atomic clusters. Unlike the high temperature 
solid state reaction, the structural arrangement or 
crystallization in the atomic clusters of the product are 
rather slow at room temperature. Perhaps, this is just 
why the amorphous iron boron alloy nanoparticles can 
thus be obtained very easily by mechanochemical 
method at room temperature. 
Although the above product contains some iron ox-
ides due to the oxidation of the iron boron alloy parti-
cles, the oxidation of the fresh iron boron alloy nano-
particles can be avoided in the preparation process by 
using the inert gas atmosphere.  
 
4. CONCLUSIONS 
 
Mechanochemical method is a convenient and prac-
tical way for synthesis of amorphous Fe-B alloy nano-
particles. Amorphous Fe-B alloy nanoparticles can very 
easily be prepared through the reaction of ferrous sul-
fate heptahydrate and sodium borohydride powders. By 
increasing the molar ratio of NaBH4/FeSO4.7H2O, the 
amount of boron in the alloy composition was increased 
and the amorphous phase formation was more favora-
ble. The optimal and suitable molar ratio of 
NaBH4/FeSO4.7H2O for the preparation of amorphous 
Fe-B alloy nanoparticles is 4. The results of various 
characterizations indicate that the product is mainly 
amorphous Fe-B alloy nanoparticles with a diameter 
below 50 nm and contains fine iron oxides nanoparticl-
es due to the surface oxidation.  
 
 
 
REFERENCES 
 
1. Y. Chen, Catalysis Today 44, 3 (1998). 
2. J. Balogh, L. Bujdoso, T. Kemeny, I. Vincze, J. Phys.: Con-
dens. Matter 9, L503 (1997). 
3. W.H. Wang, C. Dong, C.H. Shek, Mater. Sci. Eng. R44, 45 
(2004). 
4. R. Babilas, R. Nowosielski, Arch. Mater. Sci. Eng. 44, 5 
(2010). 
5. H. Habazaki, Shreir's Corrosion 3, 2192 (2009). 
6. J. Abenojar, F. Velasco, J.M. Mota, M.A. Martinez, J. Sol. 
State Chem. 177, 382 (2004). 
7. J. Saida, Mater. Sci. Eng. A 179-180, 577 (1994). 
8. J. Jiang, I. Dezsi, U. Gonser, X. Lin, J. Non-Cryst. Solids 
124, 139 (1990). 
9. S. Linderoth, S. Morup, et al. J. Appl. Phys. 67, 4472 
(1990). 
10. S. Rivas, M.A. Lopez Quintela, M.G. Bonome, R.J. Duro , 
J.M. Greneche, J. Magn. Magn. Mater. 122, 1-5 (1993). 
11. M.L. Liu, H.L. Zhou, Y.R. Chen, Y.Q. Jia, Mater. Chem. 
Phys. 89, 289 (2005). 
12. G.Q. Zhong, H.L. Zhou, Y.Q. Jia, J. Alloys Compd. 465, L1 
(2008). 
13. G.Q. Zhong, Q. Zhong, H.L. Zhou,Y.Q. Jia, Adv. Mater. 
Res. 236-238, 1717(2011). 
14. R. Wannemacher, A. Pack, and M. Quinten, Appl. Phys. 
B 68, 225 (1999). 
 
 


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The Effect of Raw Materials Molar Ratio in Mechanochemical Synthesis of Amorphous Fe-B Alloy Nanoparticles

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