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Preparation and microwave absorption properties of carbon nanocoils
Materials Letters 62 (2008) 3704–3706
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 microwave absorption properties of carbon nanocoils Dong-Lin Zhao ⁎, Zeng-Min Shen State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
A R T I C L E
I N F O
Article history: Received 31 December 2007 Accepted 9 April 2008 Available online 16 April 2008 Keywords: Carbon nanocoil Microwave absorption Complex permittivity and permeability Chemical vapour deposition Nanocomposites
A B S T R A C T Carbon nanocoils were prepared by chemical vapour deposition, using commercial acetylene as carbon source, a nickel plate as a catalyst and a phosphorous compound as additive. The carbon nanocoils with diameters in the range of 80–100 nm and lengths of 5–50 µm are visible from FESEM images. Microwave absorption, complex permittivity and permeability of carbon nanocoils have been investigated at 2–18 GHz. Carbon nanocoils are chiral microwave absorbing materials and exhibit superior microwave absorption compared with the larger carbon microcoils. The reflection loss of the Nomex honeycomb sandwich composites filled with the carbon nanocoils is below −10 dB (90% absorption) at 8.9–18 GHz in the range of 2–18 GHz, and the minimum value is −32.23 dB at 12 GHz. The bandwidth corresponding to the reflection loss below −10 dB is 8.1 GHz. © 2008 Elsevier B.V. All rights reserved.
1. Introduction
2. Experimental
Microwave absorbing materials have attracted significant interest because of their applications in commercial and military industries. The manufacture of microwave absorbing materials involves the use of compounds capable of generating dielectric and/or magnetic losses when impinged by an electromagnetic wave. Chiral materials such as springs have been drawing considerable attention due to their potential applications in the microwave absorbing materials. Researchers have done much work on coiled chiral materials as microwave absorber [1–3]. Comparing with general dielectric materials, chiral materials have a chiral admittance ξ besides the parameters of permittivity (ε) and permeability (μ), which makes it easier to design microwave absorbing materials. However, it is difficult to obtain and use these artificial metal or ceramic coils described in the above researches. Comparing with those coils, carbon microcoils and nanocoils prepared by chemical vapour deposition (CVD) are lightweight and easily obtained, which will provide a better selection for practical applications [4–7]. Some researchers and we have investigated the microwave electromagnetic characteristics [8] and the microwave absorbing properties of carbon microcoils [9,10]. In this study, we attempt to investigate the microwave electromagnetic response of the carbon nanocoils. The ε, μ and microwave absorbing property of the carbon nanoocoils have been investigated. The microwave absorbing mechanism is also discussed.
Carbon nanocoils were prepared by CVD, using commercial acetylene as carbon source, a nickel plate as a catalyst and a phosphorous compound as additive. Carbon nanocoils were obtained with total gas flow rate of 180 mL/min. Reaction conditions are as follows: reaction temperature 780 °C, the ratio of C2H2 to H2 1:3 and the flow rate of phosphorous compound additive 0.8 mL/min. The morphology and microstructure of the carbon nanocoils were observed by using a field-emission scanning electron microscopy (FESEM, Hitachi S-4700). X-ray diffraction (XRD) spectrum was carried out with D/Max2500VB2 + PC diffraction apparatus. The complex permittivity and permeability of the carbon nanocoil/paraffin wax composites were measured by the coaxial line method at 2–18 GHz using HP8722ES network analyzer in agreement with the method reported in [11]. The content of the carbon nanocoils is 10 wt.%. The real part (ɛ′) and imaginary part (ɛ″) of the permittivity of paraffin wax are 2.22–2.26 and 0–0.02 at 2–18 GHz respectively, the real part (µ′) and imaginary part (µ″) of permeability, 0.97–1.01 and 0–0.12. The Nomex honeycomb sandwich composites filled with the carbon nanocoils is comprised of two E-glass fiber reinforced composite (GFRC) plates and one Nomex honeycomb plate, which have a size of 180 × 180 mm2. One GFRC plate was used as the ground panel and the other as face panel of the Nomex honeycomb sandwich composites. The GFRC plate is 0.58 mm thick, which was laminated with epoxy curing resin. Nomex honeycomb plate is hexangular honeycomb plate made of organic fiber Nomex paper in which 170 g carbon nanocoils per square meter were filled. The thickness of the Nomex honeycomb sandwich composites is 9.6 mm. The microwave
⁎ Corresponding author. Tel.: +86 10 64434914; fax: +86 10 64454912. E-mail address: [email protected] (D.-L. Zhao). 0167-577X/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.matlet.2008.04.032
D.-L. Zhao, Z.-M. Shen / Materials Letters 62 (2008) 3704–3706
3705
Fig. 1. SEM images of the carbon nanocoils.
absorbing property of the Nomex honeycomb sandwich composites filled with the carbon nanocoils was measured in agreement with the method reported in [12]. 3. Results and discussion Fig. 1 shows the SEM image of the carbon nanocoils. As seen from Fig. 1, the carbon nanocoils have a diameter in the range of 80–100 nm with lengths of 5–50 μm. Fig. 2 shows the X-ray diffraction (XRD) pattern of the carbon nanocoils. The d002 of the carbon nanocoils is 0.3578 nm. La and Lc of the carbon nanocoils are 0.5089 and 0.2894 nm, respectively.
Fig. 2. XRD pattern of the carbon nanocoils.
Fig. 3. Frequency dependence of the permittivity (a), permeability (b), tgδɛ and tgδµ (c) of the carbon nanocoil/paraffin wax composites.
Fig. 4. Microwave reflectivity of the Nomex honeycomb sandwich composites filled with carbon nanocoils.
3706
D.-L. Zhao, Z.-M. Shen / Materials Letters 62 (2008) 3704–3706
In order to investigate the intrinsic reasons for microwave absorption of the carbon nanocoils, we measured the complex permittivity and permeability of the carbon nanocoil/paraffin wax composites by the coaxial line method at 2–18 GHz. As illustrated in Fig. 3, the ɛ′, ɛ″ and dielectric dissipation factor (tgδɛ = ɛ″/ɛ′) of the carbon nanocoil/ paraffin wax composites are 14.85–36.36, 12.12–30.52 and 0.63–0.84, respectively. The µ′, µ″ and magnetic dissipation factor tgδµ (µ″/µ′) are 0.98–1.07, 0–0.14 and 0–0.13, respectively. So the microwave enhancement absorption of the carbon nanocoils results mainly from dielectric loss rather than magnetic loss. Fig. 4 shows the frequency dependence of the reflection loss of the Nomex honeycomb sandwich composites filled with carbon nanocoils. As can be seen from Fig. 4, the reflection loss of the carbon nanocoil sandwich composites is below −10 dB (90% absorption) at 8.9–18 GHz in the range of 2–18 GHz, and the minimum value is −32.23 dB at 12 GHz. The bandwidth corresponding to the reflection loss below −10 dB is 8.1 GHz. But the reflection loss of the carbon microcoil sandwich composites is below −10 dB at 10–15 GHz, and the minimum value is −18 dB at 12.4 GHz [10]. Carbon nanocoils exhibit superior microwave absorption compared with the larger carbon microcoils. Carbon nanocoils are chiral microwave absorbing materials and exhibit superior microwave absorption compared with the larger carbon microcoils. The microwave enhancement absorption of the carbon nanocoils results mainly from dielectric loss rather than magnetic loss. And the interfacial multipoles contribute to the strong absorption of the carbon nanocoils. The carbon nanocoils will be good candidates for the microwave absorbing materials.
Acknowledgement This work was supported by the Natural Science Foundation of China (Grant No. 50672004). References [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12]
Varadan VV, Ro R, Varadan VK. Radio Sci 1994;29:9–22. Guerin F, Varadan VK, Varadan VV. J Wave-Mater Interaction 1992;7:279–93. Ge FD, Chen LM, Zhu J. Int J Infrared Milli Waves 1996;17:255–68. Motojima S, Asakura S, Hirata M, Iwanaga H. Mater Sci Eng B 1995;34:9–11. Motojima S, Chen XQ, Yang S, Hasegawa M. Diam Relat Mater 2004;13:1989–92. Liu YF, Shen ZM. Carbon 2005;43:1574–7. Qin Y, Zhang Z, Cui Z. Carbon 2004;42:1917–22. Du JH, Sun C, Bai S, Su G, Ying Z, Cheng HM. J Mater Res 2002;17:1232–6. Xie G, Wang Z, Cui Z, Shi Y. Carbon 2005;43:3181–3. Shen ZM, Ge M, Zhao DL. New Carbon Mater 2005;20:289–93. Liu XL, Zhao DL. Adv Mater Res 2006;11–12:559–62. Yang J, Shen ZM, Hao ZB. Carbon 2004;42:1182–5.
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 microwave absorption properties of carbon nanocoils Dong-Lin Zhao ⁎, Zeng-Min Shen State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
A R T I C L E
I N F O
Article history: Received 31 December 2007 Accepted 9 April 2008 Available online 16 April 2008 Keywords: Carbon nanocoil Microwave absorption Complex permittivity and permeability Chemical vapour deposition Nanocomposites
A B S T R A C T Carbon nanocoils were prepared by chemical vapour deposition, using commercial acetylene as carbon source, a nickel plate as a catalyst and a phosphorous compound as additive. The carbon nanocoils with diameters in the range of 80–100 nm and lengths of 5–50 µm are visible from FESEM images. Microwave absorption, complex permittivity and permeability of carbon nanocoils have been investigated at 2–18 GHz. Carbon nanocoils are chiral microwave absorbing materials and exhibit superior microwave absorption compared with the larger carbon microcoils. The reflection loss of the Nomex honeycomb sandwich composites filled with the carbon nanocoils is below −10 dB (90% absorption) at 8.9–18 GHz in the range of 2–18 GHz, and the minimum value is −32.23 dB at 12 GHz. The bandwidth corresponding to the reflection loss below −10 dB is 8.1 GHz. © 2008 Elsevier B.V. All rights reserved.
1. Introduction
2. Experimental
Microwave absorbing materials have attracted significant interest because of their applications in commercial and military industries. The manufacture of microwave absorbing materials involves the use of compounds capable of generating dielectric and/or magnetic losses when impinged by an electromagnetic wave. Chiral materials such as springs have been drawing considerable attention due to their potential applications in the microwave absorbing materials. Researchers have done much work on coiled chiral materials as microwave absorber [1–3]. Comparing with general dielectric materials, chiral materials have a chiral admittance ξ besides the parameters of permittivity (ε) and permeability (μ), which makes it easier to design microwave absorbing materials. However, it is difficult to obtain and use these artificial metal or ceramic coils described in the above researches. Comparing with those coils, carbon microcoils and nanocoils prepared by chemical vapour deposition (CVD) are lightweight and easily obtained, which will provide a better selection for practical applications [4–7]. Some researchers and we have investigated the microwave electromagnetic characteristics [8] and the microwave absorbing properties of carbon microcoils [9,10]. In this study, we attempt to investigate the microwave electromagnetic response of the carbon nanocoils. The ε, μ and microwave absorbing property of the carbon nanoocoils have been investigated. The microwave absorbing mechanism is also discussed.
Carbon nanocoils were prepared by CVD, using commercial acetylene as carbon source, a nickel plate as a catalyst and a phosphorous compound as additive. Carbon nanocoils were obtained with total gas flow rate of 180 mL/min. Reaction conditions are as follows: reaction temperature 780 °C, the ratio of C2H2 to H2 1:3 and the flow rate of phosphorous compound additive 0.8 mL/min. The morphology and microstructure of the carbon nanocoils were observed by using a field-emission scanning electron microscopy (FESEM, Hitachi S-4700). X-ray diffraction (XRD) spectrum was carried out with D/Max2500VB2 + PC diffraction apparatus. The complex permittivity and permeability of the carbon nanocoil/paraffin wax composites were measured by the coaxial line method at 2–18 GHz using HP8722ES network analyzer in agreement with the method reported in [11]. The content of the carbon nanocoils is 10 wt.%. The real part (ɛ′) and imaginary part (ɛ″) of the permittivity of paraffin wax are 2.22–2.26 and 0–0.02 at 2–18 GHz respectively, the real part (µ′) and imaginary part (µ″) of permeability, 0.97–1.01 and 0–0.12. The Nomex honeycomb sandwich composites filled with the carbon nanocoils is comprised of two E-glass fiber reinforced composite (GFRC) plates and one Nomex honeycomb plate, which have a size of 180 × 180 mm2. One GFRC plate was used as the ground panel and the other as face panel of the Nomex honeycomb sandwich composites. The GFRC plate is 0.58 mm thick, which was laminated with epoxy curing resin. Nomex honeycomb plate is hexangular honeycomb plate made of organic fiber Nomex paper in which 170 g carbon nanocoils per square meter were filled. The thickness of the Nomex honeycomb sandwich composites is 9.6 mm. The microwave
⁎ Corresponding author. Tel.: +86 10 64434914; fax: +86 10 64454912. E-mail address: [email protected] (D.-L. Zhao). 0167-577X/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.matlet.2008.04.032
D.-L. Zhao, Z.-M. Shen / Materials Letters 62 (2008) 3704–3706
3705
Fig. 1. SEM images of the carbon nanocoils.
absorbing property of the Nomex honeycomb sandwich composites filled with the carbon nanocoils was measured in agreement with the method reported in [12]. 3. Results and discussion Fig. 1 shows the SEM image of the carbon nanocoils. As seen from Fig. 1, the carbon nanocoils have a diameter in the range of 80–100 nm with lengths of 5–50 μm. Fig. 2 shows the X-ray diffraction (XRD) pattern of the carbon nanocoils. The d002 of the carbon nanocoils is 0.3578 nm. La and Lc of the carbon nanocoils are 0.5089 and 0.2894 nm, respectively.
Fig. 2. XRD pattern of the carbon nanocoils.
Fig. 3. Frequency dependence of the permittivity (a), permeability (b), tgδɛ and tgδµ (c) of the carbon nanocoil/paraffin wax composites.
Fig. 4. Microwave reflectivity of the Nomex honeycomb sandwich composites filled with carbon nanocoils.
3706
D.-L. Zhao, Z.-M. Shen / Materials Letters 62 (2008) 3704–3706
In order to investigate the intrinsic reasons for microwave absorption of the carbon nanocoils, we measured the complex permittivity and permeability of the carbon nanocoil/paraffin wax composites by the coaxial line method at 2–18 GHz. As illustrated in Fig. 3, the ɛ′, ɛ″ and dielectric dissipation factor (tgδɛ = ɛ″/ɛ′) of the carbon nanocoil/ paraffin wax composites are 14.85–36.36, 12.12–30.52 and 0.63–0.84, respectively. The µ′, µ″ and magnetic dissipation factor tgδµ (µ″/µ′) are 0.98–1.07, 0–0.14 and 0–0.13, respectively. So the microwave enhancement absorption of the carbon nanocoils results mainly from dielectric loss rather than magnetic loss. Fig. 4 shows the frequency dependence of the reflection loss of the Nomex honeycomb sandwich composites filled with carbon nanocoils. As can be seen from Fig. 4, the reflection loss of the carbon nanocoil sandwich composites is below −10 dB (90% absorption) at 8.9–18 GHz in the range of 2–18 GHz, and the minimum value is −32.23 dB at 12 GHz. The bandwidth corresponding to the reflection loss below −10 dB is 8.1 GHz. But the reflection loss of the carbon microcoil sandwich composites is below −10 dB at 10–15 GHz, and the minimum value is −18 dB at 12.4 GHz [10]. Carbon nanocoils exhibit superior microwave absorption compared with the larger carbon microcoils. Carbon nanocoils are chiral microwave absorbing materials and exhibit superior microwave absorption compared with the larger carbon microcoils. The microwave enhancement absorption of the carbon nanocoils results mainly from dielectric loss rather than magnetic loss. And the interfacial multipoles contribute to the strong absorption of the carbon nanocoils. The carbon nanocoils will be good candidates for the microwave absorbing materials.
Acknowledgement This work was supported by the Natural Science Foundation of China (Grant No. 50672004). References [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12]
Varadan VV, Ro R, Varadan VK. Radio Sci 1994;29:9–22. Guerin F, Varadan VK, Varadan VV. J Wave-Mater Interaction 1992;7:279–93. Ge FD, Chen LM, Zhu J. Int J Infrared Milli Waves 1996;17:255–68. Motojima S, Asakura S, Hirata M, Iwanaga H. Mater Sci Eng B 1995;34:9–11. Motojima S, Chen XQ, Yang S, Hasegawa M. Diam Relat Mater 2004;13:1989–92. Liu YF, Shen ZM. Carbon 2005;43:1574–7. Qin Y, Zhang Z, Cui Z. Carbon 2004;42:1917–22. Du JH, Sun C, Bai S, Su G, Ying Z, Cheng HM. J Mater Res 2002;17:1232–6. Xie G, Wang Z, Cui Z, Shi Y. Carbon 2005;43:3181–3. Shen ZM, Ge M, Zhao DL. New Carbon Mater 2005;20:289–93. Liu XL, Zhao DL. Adv Mater Res 2006;11–12:559–62. Yang J, Shen ZM, Hao ZB. Carbon 2004;42:1182–5.