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Preparation and growth of Ni–Cu alloy nanoparticles prepared by arc plasma evaporation
Materials Letters 64 (2010) 1229–1231
Contents lists available at ScienceDirect
Materials Letters j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / m a t l e t
Preparation and growth of Ni–Cu alloy nanoparticles prepared by arc plasma evaporation A.J. Song a,b, M.Z. Ma a, W.G. Zhang a,b, H.T. Zong a, S.X. Liang a, Q.H. Hao a, R.Z. Zhou a, Q. Jing a, R.P. Liu a,⁎ a b
State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao, Hebei, 066004, PR China Chemistry Department, Hebei Normal University of Science & Technology, Qinhuangdao, Hebei, 066004, PR China
a r t i c l e
i n f o
Article history: Received 28 September 2009 Accepted 28 February 2010 Available online 6 March 2010 Keywords: Ni–Cu alloy nanoparticles Arc plasma evaporation Powder technology Crystal growth
a b s t r a c t Nano-scale alloy powders, with the average particle size of 50 nm and face-centered cubic structure, were prepared from NixCu1 − x (20% b x b 80 at.%) bulk alloys by arc plasma evaporation. Because of the difference in evaporation rates for both nickel and copper in the alloy melt, the composition of the prepared powders is found to be different from that of raw bulk alloys in most of the cases. Thus the composition relationship between the powders and raw alloys are constructed in the present work. In order to control the size distribution of the powders, the aggregation and growth process of the nanoparticles are analyzed. © 2010 Elsevier B.V. All rights reserved.
1. Introduction Ni–Cu bulk materials have been used extensively in corrosion resistance [1] and modified glassy carbon electrodes [2]. When made into nano-powders, they present excellent catalytic properties, which may be applied, for example, in cracking of methane [3] and pyrolysis of ammonium perchlorate [4]. The Ni–Cu nanoparticles may also be used as addition to the metal–ceramic composites for space components. In the past decades, more attention has been given to the understanding of the special properties of the nanoparticles, but less progress has been obtained in controlling of particle composition and size distribution, which are rather important for applications. Among various nanopowder synthetic methods, the arc plasma evaporation technique demonstrates some advantages, such as pure surface, narrow size distribution and alterable properties of the prepared particles. Successful preparation of pure metal nanopowders with the technique has been reported [5,6], but alloy nanopowders have been rarely synthesized by this way because of the problem of unpredictable product composition [7]. Binary and multi-component alloys are important materials [8–10], and more excellent properties are expected for nano scale powders. In this work, Ni–Cu alloy nanopowders are prepared from NixCu1 − x (20 at.% b x b 80 at.%) bulk alloys by arc plasma evaporation method. The particle size, the structure and the composition of the nanoparticles are determined. And the stability of the nanoparticles is
⁎ Corresponding author. State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, PR China. E-mail address: [email protected] (R.P. Liu). 0167-577X/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.matlet.2010.02.061
investigated based on the analysis of the agglomeration and growth processes. 2. Experiments Pure Ni (purity ∼ 99.99 wt.%) and Cu (purity ∼ 99.99 wt.%) bulk materials were melted in argon arc furnace to make raw alloys, which is used for preparation of the alloy powders. Arc plasma evaporation method, as shown in Fig. 1, was applied. In the melting chamber, the water-cooled copper crucible served as anode and the water cooled tungsten electrode was used as cathode. The melting chamber and the powder collection chamber were pumped to a vacuum of 10−3 Pa, and then backfilled with argon and hydrogen with a mixture ratio of 2 to 1. The argon and hydrogen mixture was forced to circulate in the melting and the powder collection chambers. The high temperature of the arc, which roughly exceeded 3000 °C, drove the melted alloy to become metal vapors. The vapors were taken to the collection chamber, where powders were collected. The crystal structure was characterized by X-ray diffraction (XRD). The particles size and morphological analysis were investigated by TEM (transmission electron microscopy) and FESEM (field-emission scanning electron microscopy). The composition was determined by X-ray fluorescence spectrometry (XRF). 3. Results and discussion Fig. 2 shows the XRD patterns of the NixCu1 − x (20% b x b 80 at.%) nanoparticles. The XRD peaks of the nanoparticles, which obtained from the different bulk alloys, are similar with each other. The five strong peaks correspond to (111), (200), (220), (311) and (222)
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A.J. Song et al. / Materials Letters 64 (2010) 1229–1231
Fig. 3. Composition trends of raw materials and nanoparticles. Fig. 1. Schematic diagram of the experimental setup.
planes of the face centered cubic (fcc) structure, the same as that of the bulk raw material. No other diffraction is detected, indicating that the samples have high purity and no obvious oxidation occurred. Because of small size and surface effect, the diffraction peaks are evidently broadened. The average crystalline size calculated according to Scherrer equation [11] is about 50 nm. Fig. 3 exhibits the composition trends of the Ni–Cu nanoparticles prepared from the NixCu1 − x (20% b x b 80 at.%) raw materials. Because nickel has lower vapor pressure than copper at the same temperature, copper was evaporated relatively faster from the NixCu1 − x alloy melts. The composition of the particles prepared from the alloys is seen to differ from that of the raw alloys in most of the cases, as shown in Fig. 3, where the real and dashed lines represent the composition of the raw materials and the as-prepared particles, respectively. Fig. 4 shows the representative micrographs of the as-prepared Ni–Cu powders. Most of the particles are identified to be nano-scaled, distributed from 20 to 100 nm (Fig. 4a and b). Such a good size distribution was benefited by the forced flow of the argon and hydrogen mixture in the chamber system, because only occasionally observed apparent agglomeration and growth of the nanoparticles in
the collected powders. But serious agglomeration and growth of the nanoparticles in the films deposited on the evaporation chamber walls were often found without the forced flow of the argon and hydrogen mixture. The agglomeration and growth of the nanoparticles can be attributed to the surface free energy of the nanoparticles. The driving force, ΔG, for the agglomeration and growth of the nanoparticles can be calculated as following ΔG = ΔG1 −ΔG2
ð1Þ
4 3 2 ΔG1 = n⋅ πr1 ⋅Δg + n⋅4πr1 ⋅σ 3
ð2Þ
ΔG2 =
4 3 2 πr ⋅Δg + 4πr2 ⋅σ 3 2
ð3Þ
where ΔG1 is the sum of the free energy of the nanoparticles before agglomeration, ΔG2 is the free energy of the final large particle grown, Δg is the volume free energy, σ is the surface free energy, r1 is the radius of the nanoparticles before agglomeration, r2 is the radius of the resulted particles after growth, and n is the number of the nanoparticles before agglomeration. Δg and σ have constant values at fixed temperature, so ΔG is the function of radii (shown in Fig. 5). Because of the high surface free energy, the nanoparticles incline to agglomerate to decrease the system energy. The driving force rapidly decreases with the increase of the particle size. Around the size of 2– 5 μm, the driving force decreased almost to the lowest value. This may account for the experimental results that the largest particles with smooth surfaces are smaller than 5 μm (as shown in Fig. 4c and d). 4. Conclusions
Fig. 2. XRD patterns of the prepared Ni–Cu nanoparticles prepared from raw alloys with various composition.
Ni–Cu alloy nanoparticles with different chemical compositions were prepared by arc plasma evaporation technique from NixCu1 − x (20 b x b 80 at.%) bulk alloys. The average particle size was determined to be around 50 nm. The composition of the prepared particles is different from that of the raw bulk materials in most of the cases. Occasional agglomeration and growth of the particles was observed, and the behaviors were driven by the largely increased surface free energy of the nanoparticles. The largest size of the particles with smooth surfaces grown at room temperature was smaller than 5 μm.
A.J. Song et al. / Materials Letters 64 (2010) 1229–1231
1231
Fig. 4. Ni–Cu alloy particles. (a) and (b) show the original size and distribution (TEM micrograph) of the nanoparticles. (c) and (d) show the perfect and imperfect spherical particles after agglomeration and growth (FESEM micrograph), which were more often observed in the deposited film.
References
Fig. 5. The driving force for the growth of the nanoparticles.
Acknowledgements This work was supported by the NSFC (Grant No. 50731005/ 50821001), SKPBRC (Grant No. 2010CB731604/2006CB605201), PCSIRT (Grant No. IRT0650), Hebei NSF (Grant No. E 2009000449) and Hebei EDF (Grant No. Z200813).
[1] Paulus JA, Parida GR, Tucker RD, Park JB. Corrosion analysis of NiCu and PdCo thermal seed alloys used as interstitial hyperthermia implants. Biomaterials 1997;18:1609–14. [2] Danaee I, Jafarian M, Forouzandeh F, Gobal F, Mahjani MG. Electrocatalytic oxidation of methanol on Ni and NiCu alloy modified glassy carbon electrode. Int J Hydrogen Energy 2008;33:4367–76. [3] Ismael G, Juan C, Caribay U, Miguel G. Effect of Cu on Ni nanoparticles used for the generation of carbon nanotubes by catalytic cracking of methane. Catal Today 2010;149:352–7. [4] Liu LL, Li FS, Tan LH, Yang Y, Zhang QS. Catalysis of nano-NiCu composite powder on the pyrolysis of AP and AP/HTPB propellant. J Solid Rocket Technol 2007;30: 52–6. [5] Wei ZQ, Xia TD, Li BF, Wang J, Wu ZG, Yan PX. Efficient preparation for Ni nanopowders by anodic arc plasma. Mater Lett 2006;60:766–70. [6] Champion Y, Bigot. Preparation and characterization of nanocrystalline copper powders. Scripta Mater 1996;35:517–22. [7] Duhamel C, Bonnentien JL, Champion Y. Synthesis and characterization of Ag doped Cu nanoparticles. J Alloys Compd 2008;460:191–5. [8] Kuo SY, Shiau LC, Chen KH. Buckling analysis of shape memory alloy reinforced composite laminates. Compos Struct 2009;90:188–95. [9] Nuetzel JA, Unrau CJ, Indeck R, Axelbaum RL. Flame synthesis of superparamagnetic Fe/Nb nanocomposites for biomedical applications. P Combust Inst 2009;32: 1871–7. [10] Wei ZQ, Xia TD, Ma J, Dai JF, Feng WJ, Wang Q, et al. Trans Nonferrous Met Soc China 2006;16:168–72. [11] Allen WB, Kenneth O, Thomas R, Ignatius YC. On the estimation of average crystallite size of zeolites from the Scherrer equation: a critical evaluation of its application to zeolites with one-dimensional pore systems. Microporous Mesoporous Mater 2009;117:75–90.
Contents lists available at ScienceDirect
Materials Letters j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / m a t l e t
Preparation and growth of Ni–Cu alloy nanoparticles prepared by arc plasma evaporation A.J. Song a,b, M.Z. Ma a, W.G. Zhang a,b, H.T. Zong a, S.X. Liang a, Q.H. Hao a, R.Z. Zhou a, Q. Jing a, R.P. Liu a,⁎ a b
State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao, Hebei, 066004, PR China Chemistry Department, Hebei Normal University of Science & Technology, Qinhuangdao, Hebei, 066004, PR China
a r t i c l e
i n f o
Article history: Received 28 September 2009 Accepted 28 February 2010 Available online 6 March 2010 Keywords: Ni–Cu alloy nanoparticles Arc plasma evaporation Powder technology Crystal growth
a b s t r a c t Nano-scale alloy powders, with the average particle size of 50 nm and face-centered cubic structure, were prepared from NixCu1 − x (20% b x b 80 at.%) bulk alloys by arc plasma evaporation. Because of the difference in evaporation rates for both nickel and copper in the alloy melt, the composition of the prepared powders is found to be different from that of raw bulk alloys in most of the cases. Thus the composition relationship between the powders and raw alloys are constructed in the present work. In order to control the size distribution of the powders, the aggregation and growth process of the nanoparticles are analyzed. © 2010 Elsevier B.V. All rights reserved.
1. Introduction Ni–Cu bulk materials have been used extensively in corrosion resistance [1] and modified glassy carbon electrodes [2]. When made into nano-powders, they present excellent catalytic properties, which may be applied, for example, in cracking of methane [3] and pyrolysis of ammonium perchlorate [4]. The Ni–Cu nanoparticles may also be used as addition to the metal–ceramic composites for space components. In the past decades, more attention has been given to the understanding of the special properties of the nanoparticles, but less progress has been obtained in controlling of particle composition and size distribution, which are rather important for applications. Among various nanopowder synthetic methods, the arc plasma evaporation technique demonstrates some advantages, such as pure surface, narrow size distribution and alterable properties of the prepared particles. Successful preparation of pure metal nanopowders with the technique has been reported [5,6], but alloy nanopowders have been rarely synthesized by this way because of the problem of unpredictable product composition [7]. Binary and multi-component alloys are important materials [8–10], and more excellent properties are expected for nano scale powders. In this work, Ni–Cu alloy nanopowders are prepared from NixCu1 − x (20 at.% b x b 80 at.%) bulk alloys by arc plasma evaporation method. The particle size, the structure and the composition of the nanoparticles are determined. And the stability of the nanoparticles is
⁎ Corresponding author. State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, PR China. E-mail address: [email protected] (R.P. Liu). 0167-577X/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.matlet.2010.02.061
investigated based on the analysis of the agglomeration and growth processes. 2. Experiments Pure Ni (purity ∼ 99.99 wt.%) and Cu (purity ∼ 99.99 wt.%) bulk materials were melted in argon arc furnace to make raw alloys, which is used for preparation of the alloy powders. Arc plasma evaporation method, as shown in Fig. 1, was applied. In the melting chamber, the water-cooled copper crucible served as anode and the water cooled tungsten electrode was used as cathode. The melting chamber and the powder collection chamber were pumped to a vacuum of 10−3 Pa, and then backfilled with argon and hydrogen with a mixture ratio of 2 to 1. The argon and hydrogen mixture was forced to circulate in the melting and the powder collection chambers. The high temperature of the arc, which roughly exceeded 3000 °C, drove the melted alloy to become metal vapors. The vapors were taken to the collection chamber, where powders were collected. The crystal structure was characterized by X-ray diffraction (XRD). The particles size and morphological analysis were investigated by TEM (transmission electron microscopy) and FESEM (field-emission scanning electron microscopy). The composition was determined by X-ray fluorescence spectrometry (XRF). 3. Results and discussion Fig. 2 shows the XRD patterns of the NixCu1 − x (20% b x b 80 at.%) nanoparticles. The XRD peaks of the nanoparticles, which obtained from the different bulk alloys, are similar with each other. The five strong peaks correspond to (111), (200), (220), (311) and (222)
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A.J. Song et al. / Materials Letters 64 (2010) 1229–1231
Fig. 3. Composition trends of raw materials and nanoparticles. Fig. 1. Schematic diagram of the experimental setup.
planes of the face centered cubic (fcc) structure, the same as that of the bulk raw material. No other diffraction is detected, indicating that the samples have high purity and no obvious oxidation occurred. Because of small size and surface effect, the diffraction peaks are evidently broadened. The average crystalline size calculated according to Scherrer equation [11] is about 50 nm. Fig. 3 exhibits the composition trends of the Ni–Cu nanoparticles prepared from the NixCu1 − x (20% b x b 80 at.%) raw materials. Because nickel has lower vapor pressure than copper at the same temperature, copper was evaporated relatively faster from the NixCu1 − x alloy melts. The composition of the particles prepared from the alloys is seen to differ from that of the raw alloys in most of the cases, as shown in Fig. 3, where the real and dashed lines represent the composition of the raw materials and the as-prepared particles, respectively. Fig. 4 shows the representative micrographs of the as-prepared Ni–Cu powders. Most of the particles are identified to be nano-scaled, distributed from 20 to 100 nm (Fig. 4a and b). Such a good size distribution was benefited by the forced flow of the argon and hydrogen mixture in the chamber system, because only occasionally observed apparent agglomeration and growth of the nanoparticles in
the collected powders. But serious agglomeration and growth of the nanoparticles in the films deposited on the evaporation chamber walls were often found without the forced flow of the argon and hydrogen mixture. The agglomeration and growth of the nanoparticles can be attributed to the surface free energy of the nanoparticles. The driving force, ΔG, for the agglomeration and growth of the nanoparticles can be calculated as following ΔG = ΔG1 −ΔG2
ð1Þ
4 3 2 ΔG1 = n⋅ πr1 ⋅Δg + n⋅4πr1 ⋅σ 3
ð2Þ
ΔG2 =
4 3 2 πr ⋅Δg + 4πr2 ⋅σ 3 2
ð3Þ
where ΔG1 is the sum of the free energy of the nanoparticles before agglomeration, ΔG2 is the free energy of the final large particle grown, Δg is the volume free energy, σ is the surface free energy, r1 is the radius of the nanoparticles before agglomeration, r2 is the radius of the resulted particles after growth, and n is the number of the nanoparticles before agglomeration. Δg and σ have constant values at fixed temperature, so ΔG is the function of radii (shown in Fig. 5). Because of the high surface free energy, the nanoparticles incline to agglomerate to decrease the system energy. The driving force rapidly decreases with the increase of the particle size. Around the size of 2– 5 μm, the driving force decreased almost to the lowest value. This may account for the experimental results that the largest particles with smooth surfaces are smaller than 5 μm (as shown in Fig. 4c and d). 4. Conclusions
Fig. 2. XRD patterns of the prepared Ni–Cu nanoparticles prepared from raw alloys with various composition.
Ni–Cu alloy nanoparticles with different chemical compositions were prepared by arc plasma evaporation technique from NixCu1 − x (20 b x b 80 at.%) bulk alloys. The average particle size was determined to be around 50 nm. The composition of the prepared particles is different from that of the raw bulk materials in most of the cases. Occasional agglomeration and growth of the particles was observed, and the behaviors were driven by the largely increased surface free energy of the nanoparticles. The largest size of the particles with smooth surfaces grown at room temperature was smaller than 5 μm.
A.J. Song et al. / Materials Letters 64 (2010) 1229–1231
1231
Fig. 4. Ni–Cu alloy particles. (a) and (b) show the original size and distribution (TEM micrograph) of the nanoparticles. (c) and (d) show the perfect and imperfect spherical particles after agglomeration and growth (FESEM micrograph), which were more often observed in the deposited film.
References
Fig. 5. The driving force for the growth of the nanoparticles.
Acknowledgements This work was supported by the NSFC (Grant No. 50731005/ 50821001), SKPBRC (Grant No. 2010CB731604/2006CB605201), PCSIRT (Grant No. IRT0650), Hebei NSF (Grant No. E 2009000449) and Hebei EDF (Grant No. Z200813).
[1] Paulus JA, Parida GR, Tucker RD, Park JB. Corrosion analysis of NiCu and PdCo thermal seed alloys used as interstitial hyperthermia implants. Biomaterials 1997;18:1609–14. [2] Danaee I, Jafarian M, Forouzandeh F, Gobal F, Mahjani MG. Electrocatalytic oxidation of methanol on Ni and NiCu alloy modified glassy carbon electrode. Int J Hydrogen Energy 2008;33:4367–76. [3] Ismael G, Juan C, Caribay U, Miguel G. Effect of Cu on Ni nanoparticles used for the generation of carbon nanotubes by catalytic cracking of methane. Catal Today 2010;149:352–7. [4] Liu LL, Li FS, Tan LH, Yang Y, Zhang QS. Catalysis of nano-NiCu composite powder on the pyrolysis of AP and AP/HTPB propellant. J Solid Rocket Technol 2007;30: 52–6. [5] Wei ZQ, Xia TD, Li BF, Wang J, Wu ZG, Yan PX. Efficient preparation for Ni nanopowders by anodic arc plasma. Mater Lett 2006;60:766–70. [6] Champion Y, Bigot. Preparation and characterization of nanocrystalline copper powders. Scripta Mater 1996;35:517–22. [7] Duhamel C, Bonnentien JL, Champion Y. Synthesis and characterization of Ag doped Cu nanoparticles. J Alloys Compd 2008;460:191–5. [8] Kuo SY, Shiau LC, Chen KH. Buckling analysis of shape memory alloy reinforced composite laminates. Compos Struct 2009;90:188–95. [9] Nuetzel JA, Unrau CJ, Indeck R, Axelbaum RL. Flame synthesis of superparamagnetic Fe/Nb nanocomposites for biomedical applications. P Combust Inst 2009;32: 1871–7. [10] Wei ZQ, Xia TD, Ma J, Dai JF, Feng WJ, Wang Q, et al. Trans Nonferrous Met Soc China 2006;16:168–72. [11] Allen WB, Kenneth O, Thomas R, Ignatius YC. On the estimation of average crystallite size of zeolites from the Scherrer equation: a critical evaluation of its application to zeolites with one-dimensional pore systems. Microporous Mesoporous Mater 2009;117:75–90.