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Modified magnetic properties of MnFe2O4 by CTAB with coprecipitation method
Materials Letters 149 (2015) 22–24
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/matlet
Modified magnetic properties of MnFe2O4 by CTAB with coprecipitation method Yunong Zhang, Zhaodong Nan n College of Chemistry and Chemical Engineering, Yangzhou University, 225002 Yangzhou, People's Republic of China
art ic l e i nf o
a b s t r a c t
Article history: Received 15 December 2014 Accepted 19 February 2015 Available online 27 February 2015
Manganese ferrite (MnFe2O4) nanoparticles (NPs) were synthesized by a coprecipitation method, in which an organic alkali, 1-amino-2-propanol (MIPA), was used. The effects of hexadecyl (trimethyl) azanium bromide (CTAB) on magnetic properties of the as-synthesized MnFe2O4 NPs were studied. The saturation magnetization (Ms) is increasing with the concentration of CTAB to 0.5 mM, and it decreases when the concentration of CTAB further increased to 1.0 mM, where the maximum Ms of the sample is 54.5 emu/g. The effects of CTAB on the crystal size and particle size for these samples were studied, which were used to explain the Ms differences of these samples. At the same time, the crystallization and the adsorption of CTAB on the samples may also affect the magnetic property of the sample. & 2015 Elsevier B.V. All rights reserved.
Keywords: Nanoparticles Magnetic materials Manganese ferrite (MnFe2O4) Hexadecyl (trimethyl) azanium bromide (CTAB)
1. Introduction In the past decade, magnetic nanoparticles (MNPs) have been the subject of intense research for their unique magnetic properties and broad potential applications [1,2]. MNPs usually show a low magnetization value because of nanosized particles, which limits their practical applications. Thus, it becomes more important to study the effects on magnetic properties of MNPs [3–5]. In our previous papers, the effects of surfactants on magnetic properties of the MNPs synthesized by a solvothermal method were reported [6,7]. The aqueous coprecipitation route continues to be one of the preferred choices because of its cost-effective, readiness, and easiness in scaling-up for industrial applications [8]. However, to control the particle size, crystallinity, and magnetic properties through this method is still limited [9]. In this letter, superparamagnetic MnFe2O4 NPs through a onestep coprecipitation method were synthesized. Alkanolamines isopropanolamine (MIPA) was used as a coprecipitation agent, which was reported before in the literatures [8,10]. The effects of CTAB on magnetic properties of the MnFe2O4 NPs were studied.
2. Experimental section All the reagents were of analytical grade and used as received without further treatment, and all solutions were prepared with bidistilled water. Starting solutions were prepared by dissolving n
Corresponding author. Tel./fax: þ 86 514 87959896. E-mail address: [email protected] (Z. Nan).
http://dx.doi.org/10.1016/j.matlet.2015.02.096 0167-577X/& 2015 Elsevier B.V. All rights reserved.
5 mmol of MnCl2 in a mixed solution of 0.5 mL 37 wt% HCl and 2 mL water, and 10 mmol of FeCl3 6H2O were dissolved in 20 mL water. These two solutions were mixed at 50 1C then quickly added to 100 mL of 2.0 M 1-amino-2-propanol (MIPA) solutions contained difference concentrations of CTAB at 100 1C with mechanical stirring for about 30 min. The mixture was stirred for about 2 h at 100 1C and then cooled to room temperature. The precipitate was obtained from a magnetic separation process, and the final product was washed with water and ethanol three times, respectively, before being dried in a vacuum at 50 1C for 12 h. Transmission electron microscopy (TEM) patterns were obtained using a Tecnai 12, Philips, Netherlands. X-ray powder diffraction (XRD) patterns were recorded at room temperature by a D8 ADVANCE, Bruker-AXS, Germany, with Cu Kα radiation (λ ¼1.542 Å). Magnetic characterization was carried out at room temperature using a superconducting quantum interference device (MPMS-XL-7, Quantum Design, USA).
3. Results and discussion XRD patterns of the samples prepared with different concentrations of CTAB were determined as shown in Fig. 1A, which match well with the standard patterns of the cubic structure of spinel-phase Mn ferrite (JCPDS file no. 10-0319). Average crystallite sizes of these samples were determined from the full width half maxima (FWHM) of the (311) reflection in the XRD patterns by using the Debye Scherrer formula, which are shown in Fig. 1B. Fig. 2 shows TEM images of these samples, which indicates that NPs were synthesized under different concentrations of CTAB, and
Y. Zhang, Z. Nan / Materials Letters 149 (2015) 22–24
14
(311)
(440)
(333)
55
(400)
e
Intensity/a.u
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Size(nm)
d
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12
b
Ms(emu/g)
(220)
(111)
23
45
a 10
10
20
30
40
50
60
70
80
0.0
0.5
1.0
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concentration of CTAB(mM)
Fig. 1. (A) XRD patterns of samples synthesized under different concentrations of CTAB, (a) 0 mM, (b) 0.2 mM, (c) 0.5 mM, (d) 0.8 mM, (e) 1.0 mM; (B) crystallite size (red line), particle size (blue line), and saturation magnetization (black line) of the samples synthesized under different concentrations of CTAB. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article).
50nm
50nm
50nm
50 nm
200nm
50nm
Fig. 2. TEM images of the samples prepared under different concentrations of CTAB, (A) 0 mM, (B) 0.2 mM, (C) and (D) 0.5 mM, (E) 0.8 mM and (F) 1.0 mM.
the NPs show well dispersed and uniform size when the concentration of CTAB is 0.5 M. The average diameters of these NPs were determined as shown in Fig. 1B. These results demonstrate that the changing concentration of CTAB affected the crystallite size and particle size. Surfactant molecules capped on crystal facets and affected the growth of the crystallite. And the surfactant concentration can modify this action [11,12]. Magnetic properties of the as-prepared samples were determined at room temperature in the applied magnetic field from 20 to 20 KOe. Hysteresis loops of these samples are shown in
Fig. 3, in which saturation magnetizations (Ms) of these samples were obtained as shown in Fig. 1B. These results indicate that the magnetic properties of the samples were affected by the concentration of CTAB. When the concentration of CTAB changes from 0 to 0.5 mM, the Ms increases from 45.57 0.2 to 54.57 0.2 emu/g. When the concentration of CTAB further increases from 0.5 to 1.0 mM, the Ms decreases from 54.5 7 0.2 to 40.4 70.2 emu/g. Remanent magnetizations (Mr) and coercivities (Hc) of these samples are about equal to zero, which demonstrate that the asprepared MnFe2O4 samples are superparamagnetic.
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Y. Zhang, Z. Nan / Materials Letters 149 (2015) 22–24
60
c
40
Magnetization(emu/g)
e
b a d
20
0
as a coprecipitation agent. The effects of CTAB on magnetic properties of the as-synthesized MnFe2O4 NPs were studied. The Ms increases with the concentration of CTAB from 0 to 0.5 mM, and it decreases when the concentration of CTAB further increased to 1.0 mM, where the maximum Ms of the sample is 54.5 emu/g. At the same time, the effects of CTAB on the crystal size and particle size of these samples were studied, which was used to explain the Ms change of these samples. The crystallization and the adsorption of CTAB on the samples may also affect the magnetic property of this kind of sample.
-20
-40
Acknowledgments -60
-20000
-10000
0
10000
20000
Applied field(Oe) Fig. 3. Magnetization curve of the samples synthesized under different concentrations of CTAB, (a) 0 mM, (b) 0.2 mM, (c) 0.5 mM, (d) 0.8 mM and (e) 1.0 mM.
It is well-known that the size, structure, and shape affect the magnetic properties of the magnetic materials [13]. From Fig. 1B, it is observed that the change of the Ms is corresponding with the crystallite size and the particle size. However, the Ms value of the sample fabricated without any CTAB does not obey this change, and the crystallite size and the particle size of this sample are the minimum among these as-prepared samples, the Ms of the sample is higher than that the sample fabricated under 1.0 mM CTAB. Based on our previous report [6,7], the crystallization can also affect the magnetic properties of the sample, and the better the crystallization, the higher the saturation magnetization. At the same time, the CTAB molecules were adsorbed on the magnetic nanoparticles based on FTIR analysis (which is not shown here), and the adsorption may create repulsive (mainly as steric repulsion) forces to balance the magnetic and van der Waals attractive forces acting on the nanoparticles as like SDS (a. anionic surfactant) [14], which affected the magnetic property of the sample. 4. Conclusion Superparamagnetic MnFe2O4 NPs were synthesized by a coprecipitation method, in which 1-amino-2-propanol (MIPA) was used
The authors gratefully acknowledge the financial support from the National Nature Science Foundation of China (21273196), and the Priority Academic Program Development of Jiangsu Higher Education Institutions.
References [1] Tae HK, Eun YJ, Nyun JL, Deung JC, Kyung-Jin L, Jung-Tak J, et al. Nano Lett 2009;9:2229–33. [2] Doaga A, Cojocariu AM, Amin W, Heib F, Bender P, Hempelmann R. Mater Chem Phys 2013;143:305–10. [3] Deng H, Li XL, Peng Q, Wang X, Chen JP, Li YD. Angew Chem 2005;117:2842–5. [4] Guo P, Cui L, Wang Y, Lv M, Wang B, Zhao XS. Langmuir 2013;29:8997–9003. [5] Lu ZD, Yin YD. Chem Soc Rev 2012;41:6874–87. [6] Zhao B, Hua B, Wang H, Nan Z. Mater Lett 2013;92:75–7. [7] Zhao B, Nan Z. J Alloy Compd 2013;580:321–6. [8] Pereira C, Pereira AM, Fernandes C, Rocha M, Mendes R, Fernández-García MP, et al. Chem Mater 2012;24:1496–504. [9] Salazar JS, Perez L, de Abril O, Phuoc LT, Ihiawakrim D, Vazquez, et al. Chem Mater 2011;23:1379–86. [10] Zhang Y, Shi Q, Schliesser J, Woodfield BF, Nan Z. Inorg Chem 2014;53:10463–70. [11] Rajendran R, Muralidharan R, Gopalakrishnan RS, Chellamuthu M, Ponnusamy SU, Manikandan E. Eur J Inorg Chem 2011;35:5384–9. [12] Chen Z, Nan Z. J Colloid Interface Sci 2011;358:416–22. [13] Zhu LP, Xiao HM, Zhang WD, Yang G, Fu SY. Cryst Growth Des 2008;8:957–63. [14] Sousa MH, Tourinho FAF, Depeyrot J, da Silva GJ. MCFL Lara. J Phys Chem B 2001;105:1168–75.
Contents lists available at ScienceDirect
Materials Letters journal homepage: www.elsevier.com/locate/matlet
Modified magnetic properties of MnFe2O4 by CTAB with coprecipitation method Yunong Zhang, Zhaodong Nan n College of Chemistry and Chemical Engineering, Yangzhou University, 225002 Yangzhou, People's Republic of China
art ic l e i nf o
a b s t r a c t
Article history: Received 15 December 2014 Accepted 19 February 2015 Available online 27 February 2015
Manganese ferrite (MnFe2O4) nanoparticles (NPs) were synthesized by a coprecipitation method, in which an organic alkali, 1-amino-2-propanol (MIPA), was used. The effects of hexadecyl (trimethyl) azanium bromide (CTAB) on magnetic properties of the as-synthesized MnFe2O4 NPs were studied. The saturation magnetization (Ms) is increasing with the concentration of CTAB to 0.5 mM, and it decreases when the concentration of CTAB further increased to 1.0 mM, where the maximum Ms of the sample is 54.5 emu/g. The effects of CTAB on the crystal size and particle size for these samples were studied, which were used to explain the Ms differences of these samples. At the same time, the crystallization and the adsorption of CTAB on the samples may also affect the magnetic property of the sample. & 2015 Elsevier B.V. All rights reserved.
Keywords: Nanoparticles Magnetic materials Manganese ferrite (MnFe2O4) Hexadecyl (trimethyl) azanium bromide (CTAB)
1. Introduction In the past decade, magnetic nanoparticles (MNPs) have been the subject of intense research for their unique magnetic properties and broad potential applications [1,2]. MNPs usually show a low magnetization value because of nanosized particles, which limits their practical applications. Thus, it becomes more important to study the effects on magnetic properties of MNPs [3–5]. In our previous papers, the effects of surfactants on magnetic properties of the MNPs synthesized by a solvothermal method were reported [6,7]. The aqueous coprecipitation route continues to be one of the preferred choices because of its cost-effective, readiness, and easiness in scaling-up for industrial applications [8]. However, to control the particle size, crystallinity, and magnetic properties through this method is still limited [9]. In this letter, superparamagnetic MnFe2O4 NPs through a onestep coprecipitation method were synthesized. Alkanolamines isopropanolamine (MIPA) was used as a coprecipitation agent, which was reported before in the literatures [8,10]. The effects of CTAB on magnetic properties of the MnFe2O4 NPs were studied.
2. Experimental section All the reagents were of analytical grade and used as received without further treatment, and all solutions were prepared with bidistilled water. Starting solutions were prepared by dissolving n
Corresponding author. Tel./fax: þ 86 514 87959896. E-mail address: [email protected] (Z. Nan).
http://dx.doi.org/10.1016/j.matlet.2015.02.096 0167-577X/& 2015 Elsevier B.V. All rights reserved.
5 mmol of MnCl2 in a mixed solution of 0.5 mL 37 wt% HCl and 2 mL water, and 10 mmol of FeCl3 6H2O were dissolved in 20 mL water. These two solutions were mixed at 50 1C then quickly added to 100 mL of 2.0 M 1-amino-2-propanol (MIPA) solutions contained difference concentrations of CTAB at 100 1C with mechanical stirring for about 30 min. The mixture was stirred for about 2 h at 100 1C and then cooled to room temperature. The precipitate was obtained from a magnetic separation process, and the final product was washed with water and ethanol three times, respectively, before being dried in a vacuum at 50 1C for 12 h. Transmission electron microscopy (TEM) patterns were obtained using a Tecnai 12, Philips, Netherlands. X-ray powder diffraction (XRD) patterns were recorded at room temperature by a D8 ADVANCE, Bruker-AXS, Germany, with Cu Kα radiation (λ ¼1.542 Å). Magnetic characterization was carried out at room temperature using a superconducting quantum interference device (MPMS-XL-7, Quantum Design, USA).
3. Results and discussion XRD patterns of the samples prepared with different concentrations of CTAB were determined as shown in Fig. 1A, which match well with the standard patterns of the cubic structure of spinel-phase Mn ferrite (JCPDS file no. 10-0319). Average crystallite sizes of these samples were determined from the full width half maxima (FWHM) of the (311) reflection in the XRD patterns by using the Debye Scherrer formula, which are shown in Fig. 1B. Fig. 2 shows TEM images of these samples, which indicates that NPs were synthesized under different concentrations of CTAB, and
Y. Zhang, Z. Nan / Materials Letters 149 (2015) 22–24
14
(311)
(440)
(333)
55
(400)
e
Intensity/a.u
50
Size(nm)
d
c
12
b
Ms(emu/g)
(220)
(111)
23
45
a 10
10
20
30
40
50
60
70
80
0.0
0.5
1.0
40
concentration of CTAB(mM)
Fig. 1. (A) XRD patterns of samples synthesized under different concentrations of CTAB, (a) 0 mM, (b) 0.2 mM, (c) 0.5 mM, (d) 0.8 mM, (e) 1.0 mM; (B) crystallite size (red line), particle size (blue line), and saturation magnetization (black line) of the samples synthesized under different concentrations of CTAB. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article).
50nm
50nm
50nm
50 nm
200nm
50nm
Fig. 2. TEM images of the samples prepared under different concentrations of CTAB, (A) 0 mM, (B) 0.2 mM, (C) and (D) 0.5 mM, (E) 0.8 mM and (F) 1.0 mM.
the NPs show well dispersed and uniform size when the concentration of CTAB is 0.5 M. The average diameters of these NPs were determined as shown in Fig. 1B. These results demonstrate that the changing concentration of CTAB affected the crystallite size and particle size. Surfactant molecules capped on crystal facets and affected the growth of the crystallite. And the surfactant concentration can modify this action [11,12]. Magnetic properties of the as-prepared samples were determined at room temperature in the applied magnetic field from 20 to 20 KOe. Hysteresis loops of these samples are shown in
Fig. 3, in which saturation magnetizations (Ms) of these samples were obtained as shown in Fig. 1B. These results indicate that the magnetic properties of the samples were affected by the concentration of CTAB. When the concentration of CTAB changes from 0 to 0.5 mM, the Ms increases from 45.57 0.2 to 54.57 0.2 emu/g. When the concentration of CTAB further increases from 0.5 to 1.0 mM, the Ms decreases from 54.5 7 0.2 to 40.4 70.2 emu/g. Remanent magnetizations (Mr) and coercivities (Hc) of these samples are about equal to zero, which demonstrate that the asprepared MnFe2O4 samples are superparamagnetic.
24
Y. Zhang, Z. Nan / Materials Letters 149 (2015) 22–24
60
c
40
Magnetization(emu/g)
e
b a d
20
0
as a coprecipitation agent. The effects of CTAB on magnetic properties of the as-synthesized MnFe2O4 NPs were studied. The Ms increases with the concentration of CTAB from 0 to 0.5 mM, and it decreases when the concentration of CTAB further increased to 1.0 mM, where the maximum Ms of the sample is 54.5 emu/g. At the same time, the effects of CTAB on the crystal size and particle size of these samples were studied, which was used to explain the Ms change of these samples. The crystallization and the adsorption of CTAB on the samples may also affect the magnetic property of this kind of sample.
-20
-40
Acknowledgments -60
-20000
-10000
0
10000
20000
Applied field(Oe) Fig. 3. Magnetization curve of the samples synthesized under different concentrations of CTAB, (a) 0 mM, (b) 0.2 mM, (c) 0.5 mM, (d) 0.8 mM and (e) 1.0 mM.
It is well-known that the size, structure, and shape affect the magnetic properties of the magnetic materials [13]. From Fig. 1B, it is observed that the change of the Ms is corresponding with the crystallite size and the particle size. However, the Ms value of the sample fabricated without any CTAB does not obey this change, and the crystallite size and the particle size of this sample are the minimum among these as-prepared samples, the Ms of the sample is higher than that the sample fabricated under 1.0 mM CTAB. Based on our previous report [6,7], the crystallization can also affect the magnetic properties of the sample, and the better the crystallization, the higher the saturation magnetization. At the same time, the CTAB molecules were adsorbed on the magnetic nanoparticles based on FTIR analysis (which is not shown here), and the adsorption may create repulsive (mainly as steric repulsion) forces to balance the magnetic and van der Waals attractive forces acting on the nanoparticles as like SDS (a. anionic surfactant) [14], which affected the magnetic property of the sample. 4. Conclusion Superparamagnetic MnFe2O4 NPs were synthesized by a coprecipitation method, in which 1-amino-2-propanol (MIPA) was used
The authors gratefully acknowledge the financial support from the National Nature Science Foundation of China (21273196), and the Priority Academic Program Development of Jiangsu Higher Education Institutions.
References [1] Tae HK, Eun YJ, Nyun JL, Deung JC, Kyung-Jin L, Jung-Tak J, et al. Nano Lett 2009;9:2229–33. [2] Doaga A, Cojocariu AM, Amin W, Heib F, Bender P, Hempelmann R. Mater Chem Phys 2013;143:305–10. [3] Deng H, Li XL, Peng Q, Wang X, Chen JP, Li YD. Angew Chem 2005;117:2842–5. [4] Guo P, Cui L, Wang Y, Lv M, Wang B, Zhao XS. Langmuir 2013;29:8997–9003. [5] Lu ZD, Yin YD. Chem Soc Rev 2012;41:6874–87. [6] Zhao B, Hua B, Wang H, Nan Z. Mater Lett 2013;92:75–7. [7] Zhao B, Nan Z. J Alloy Compd 2013;580:321–6. [8] Pereira C, Pereira AM, Fernandes C, Rocha M, Mendes R, Fernández-García MP, et al. Chem Mater 2012;24:1496–504. [9] Salazar JS, Perez L, de Abril O, Phuoc LT, Ihiawakrim D, Vazquez, et al. Chem Mater 2011;23:1379–86. [10] Zhang Y, Shi Q, Schliesser J, Woodfield BF, Nan Z. Inorg Chem 2014;53:10463–70. [11] Rajendran R, Muralidharan R, Gopalakrishnan RS, Chellamuthu M, Ponnusamy SU, Manikandan E. Eur J Inorg Chem 2011;35:5384–9. [12] Chen Z, Nan Z. J Colloid Interface Sci 2011;358:416–22. [13] Zhu LP, Xiao HM, Zhang WD, Yang G, Fu SY. Cryst Growth Des 2008;8:957–63. [14] Sousa MH, Tourinho FAF, Depeyrot J, da Silva GJ. MCFL Lara. J Phys Chem B 2001;105:1168–75.