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Synthesis and characterization of MSe (M=Zn, Cd) nanorods by a new solvothermal method
Inorganic Chemistry Communications 2 (1999) 83–85
Synthesis and characterization of MSe (MsZn, Cd) nanorods by a new solvothermal method Wengzhong Wang a,b,*, Yan Geng b, Ping Yan b, Fuyu Liu b, Yi Xie b, Yitai Qian a,b a
Structure Research Laboratory, University of Science and Technology of China, Hefei, Anhui 230026, PR China b Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, PR China Received 11 September 1998
Abstract The synthesis of one-dimensional nanocrystalline materials is important for scientific research. Here a new solvothermal route to MSe (MsZn, Cd) nanorods is reported. ZnCl2 (CdCl2), Se and Na were kept in an autoclave at 80–1008C for 4–6 h, and ethylenediamine was chosen as solvent. XRD and TEM were used to characterize the as-prepared MSe (MsZn,Cd) nanorods. The results showed that diameters of the ZnSe nanorods varied from 40 to 70 nm and the lengths from 1.5 to 3 mm. The diameters of the CdSe nanorods ranged from 8 to 20 nm and the lengths ranged from 150 to 500 nm. The solvent affected the product quality and morphology. q 1999 Elsevier Science S.A. All rights reserved. Keywords: Nanorod; Zinc compounds; Cadmium compounds; Selenide compounds
In recent years, nanoscale chalcogenides have attracted considerable attention due to their remarkable properties and brilliant application prospects [1–5]. A great challenge in this research area is to explore one-dimensional nanostructure materials, such as nanotubes and nanorods [6–10]. They are the building blocks for many novel functional materials and provide the opportunity for studying further the properties of these materials. Previous works were focused on the carbon nanotube and nanorod and comparatively little research was done on other 1D structural materials. The preparation of nanorods always needs a high temperature, such as an arc discharge at a temperature of ;3000 K [11], thermal deposition of hydrocarbon [12], vapor-liquid-solid (VLS) growth [13] etc. Here we report a milder and more convenient synthetic route to MSe (MsZn, Cd) nanorods at low temperature. MSe (MsZn, Cd) are important nonlinear optical materials, electro-luminescent device materials and quantum size effect scope semiconductors [14–18]. It is reasonable to expect that 1D structural MSe have more brilliant application prospects, and this mild method could be utilized to prepare other low-dimensional materials. In our experiment, an appropriate amount of ZnCl2, Se powders and Na were put into a stainless steel autoclave with a Teflon liner, which had been already filled with ethylene-
diamine upto 90% capacity. The autoclave was maintained at 80–1008C for 4–6 h, then cooled to room temperature naturally. The precipitates were collected and washed with absolute ethanol and distilled water in sequence to remove the possible excessive Na and the by-product NaCl. The final products were dried in vacuum at 508C for 4 h. The preparation of the CdSe nanorod was similar to the above procedure except that CdCl2 was used instead of ZnCl2. The reactions were as follows: MCl 2qSeq2Na™Mseq2NaCl (MsZn, Cd)
* Corresponding author. Dept. of Chemistry: Tel.: q86-551-3601589; Fax: q86-551-2819364; E-mail: [email protected]
Fig. 1. XRD pattern of a typical nanorod sample as prepared in ethylenediamine. (a) ZnSe; (b) CdSe.
1387-7003/99/$ - see front matter q 1999 Elsevier Science S.A. All rights reserved. PII S 1 3 8 7 - 7 0 0 3 ( 9 9 ) 0 0 0 1 5 - 5
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Article: 153
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W. Wang et al. / Inorganic Chemistry Communications 2 (1999) 83–85
Fig. 2. TEM image of as-prepared sample of: (a) ZnSe nanorod prepared in ethylenediamine; (b) CdSe nanorod prepared in ethylendiamine; (c) ZnSe nanocrystal prepared in pyridine.
X-ray powder diffraction (XRD) data were collected on a Japan Rigaku D/Max gA rotation anode X-ray diffractometer with Ni-filtered Cu Ka radiation. A typical XRD pattern of the as-prepared ZnSe nanorod is shown in Fig. 1a. All peaks in the XRD pattern correspond to the reflections of cubic ZnSe. After refinement, the cell constant as0.567 nm was consistent with the reported value [19]. No impurities were detected. Fig. 1b shows the XRD pattern of the as-prepared CdSe nanorod. All peaks could be indexed as cubic CdSe [20]. After refinement, the cell constant as0.61 nm was in agreement with the reported value [20]. Transmission electron microscopy (TEM) was used to study the morphology and size distribution of the products. Data were recorded on a Hitachi H-800 transmission electron microscope. Fig. 2a shows a typical image of the as-prepared ZnSe nanorod. It clearly shows that the diameters varied from 40 to 70 nm and the lengths from 1.5 to 3 mm. For the CdSe nanorod, which is shown in Fig. 2b, the diameters ranged from 8 to 20 nm, while the lengths ranged from 150 to 500 nm. The quality of the MSe (MsZn, Cd) nanorods was affected by several factors, including the solvent, the temperature, and the length of heating. In our experiment, slightly excessive Na was essential to ensure the quality of the product, so that the Se powder could be completely converted. The possible excessive Na could be removed by absolute ethanol in the washing procedure. Otherwise, if the Se powder is excessive, it is difficult to remove from the product. As to other conditions, a higher temperature or longer time would lead to a larger grain size, while a lower temperature or shorter time would lead to incomplete reaction and low crystallinity. When the temperature was lower than 508C, the reaction could not be initiated. The reaction was carried out at 80– 1008C for 4–6 h, these being the most suitable conditions. In the formation of MSe (MsZn, Cd) nanorods, the solvent played an important role. It was observed that the Se and MCl2 powder slowly disappeared after ethylenediamine was added, and the solution color changed from transparent to brown. This supported the suggestion that amine solvents
Tuesday Mar 09 02:21 PM
dissolved the Se and metal and produced the complex, because they are strong donor ligands having N-chelation [21]. As a result, Se dispersed into solution, its surface area was greatly increased, the activity of the reactants increased, and thus the reaction temperature greatly decreased. So this new solvothermal method differs from the solid state reactions, which always need a high temperature to overcome the large diffusion distance associated with the micrometer-size reactant particles. Furthermore, possibly ethylenediamine bound to and combined Zn2q (Cd2q) and Se in a line due its structure, formed a labile bond and provided simultaneous chemical stability, templated the molecular organization, and thus MSe (MsZn, Cd) nanorods resulted [18,21,22]. When pyridine, which has a weaker N-donor but no line structure like ethylenediamine, was used as solvent instead of ethylenediamine, and the other conditions were the same as those in the experimental procedure, the final product ZnSe grains were spherical as revealed by TEM (Fig. 2c); the diameter varied from 20 to 60 nm, the average size was about 30 nm. When benzene or toluene was selected as solvent, which has no N-chelation, no reactant entered into the solution, no MSe (MsZn, Cd) were detected on the XRD pattern. The reactants remained unreacted, even when the reaction was carried out at a higher temperature (2008C) for a longer time (24 h). The above results further supported the possible growth mechanism of MSe (MsZn, Cd) nanorods.
Acknowledgements This work is supported by the Chinese National Foundation of Natural Science Research and National Nanometer Materials Climbing Program.
References [1] L.E. Brus, Appl. Phys. A 53 (1991) 465. [2] M.A. Kastrer, Phys. Today 46 (1) (1993) 24. [3] Y. Wang, N. Herron, J. Phys. Chem. 95 (1991) 525.
StyleTag -- Journal: INOCHE (Inorganic Chemistry Communications)
Article: 153
W. Wang et al. / Inorganic Chemistry Communications 2 (1999) 83–85 [4] M.G. Bawendi, P.J. Carroll, W.L. Wilson, L.E. Brus, J. Chem. Phys. 96 (1992) 946. [5] I.A. Kudryatsev, J. Opt. Soc. Am. B 10 (1993) 100. [6] A.M. Rao et al., Science 275 (1997) 187. [7] M. Bockrath et al., Science 275 (1997) 1922. [8] ?. Fan, C.M. Lieber, Nature 375 (1991) 769. [9] J. Westwater, D.P. Gosain, S. Tomiya, S. Usui, J. Vac. Sci. Technol. B 15 (3) (1997) 554. [10] K. Suenaga et al., Science 278 (1997) 653. [11] D.S. Bethune et al., Nature 363 (1993) 605. [12] V. Ivanov et al., Chem. Phys. Lett. 223 (1994) 329. [13] T.J. Trentler et al., Science 270 (1995) 1791. [14] S.A. Empedodes et al., Science 278 (1997) 2114.
Tuesday Mar 09 02:21 PM
85
[15] V.Yu. Ivanov, Yu.G. Semenov, M. Surma, M. Godlewski, Phys. Rev. B 54 (1996) 4696. [16] J.E. Bowen Katai, V.L. Colvin, A.P. Alivisatos, J. Phys. Chem. 98 (1994) 4109. [17] X.H. Wu, F.H. Li, S.P. Guo, S.X. Yuan, J. Mater. Sci. Lett. 14 (1995) 110. [18] X. Peng, M.C. Schlamp, A.V. Kadavanich, A.P. Alivisatos, J. Am. Chem. Soc. 119 (1997) 7019. [19] JCPDS No. 37-1463. [20] JCPDS No. 19-191. [21] J.R. Sachleben, W. Wooten, L. Emsley, A. Pines, V.L. Colvin, A.P. Alivistos, Chem. Phys. Lett. 198 (1992) 431. [22] A.K. Verma, T.B. Rauchfuss, S.R. Wilson, Inorg. Chem. 34 (1995) 3072.
StyleTag -- Journal: INOCHE (Inorganic Chemistry Communications)
Article: 153
Synthesis and characterization of MSe (MsZn, Cd) nanorods by a new solvothermal method Wengzhong Wang a,b,*, Yan Geng b, Ping Yan b, Fuyu Liu b, Yi Xie b, Yitai Qian a,b a
Structure Research Laboratory, University of Science and Technology of China, Hefei, Anhui 230026, PR China b Department of Chemistry, University of Science and Technology of China, Hefei, Anhui 230026, PR China Received 11 September 1998
Abstract The synthesis of one-dimensional nanocrystalline materials is important for scientific research. Here a new solvothermal route to MSe (MsZn, Cd) nanorods is reported. ZnCl2 (CdCl2), Se and Na were kept in an autoclave at 80–1008C for 4–6 h, and ethylenediamine was chosen as solvent. XRD and TEM were used to characterize the as-prepared MSe (MsZn,Cd) nanorods. The results showed that diameters of the ZnSe nanorods varied from 40 to 70 nm and the lengths from 1.5 to 3 mm. The diameters of the CdSe nanorods ranged from 8 to 20 nm and the lengths ranged from 150 to 500 nm. The solvent affected the product quality and morphology. q 1999 Elsevier Science S.A. All rights reserved. Keywords: Nanorod; Zinc compounds; Cadmium compounds; Selenide compounds
In recent years, nanoscale chalcogenides have attracted considerable attention due to their remarkable properties and brilliant application prospects [1–5]. A great challenge in this research area is to explore one-dimensional nanostructure materials, such as nanotubes and nanorods [6–10]. They are the building blocks for many novel functional materials and provide the opportunity for studying further the properties of these materials. Previous works were focused on the carbon nanotube and nanorod and comparatively little research was done on other 1D structural materials. The preparation of nanorods always needs a high temperature, such as an arc discharge at a temperature of ;3000 K [11], thermal deposition of hydrocarbon [12], vapor-liquid-solid (VLS) growth [13] etc. Here we report a milder and more convenient synthetic route to MSe (MsZn, Cd) nanorods at low temperature. MSe (MsZn, Cd) are important nonlinear optical materials, electro-luminescent device materials and quantum size effect scope semiconductors [14–18]. It is reasonable to expect that 1D structural MSe have more brilliant application prospects, and this mild method could be utilized to prepare other low-dimensional materials. In our experiment, an appropriate amount of ZnCl2, Se powders and Na were put into a stainless steel autoclave with a Teflon liner, which had been already filled with ethylene-
diamine upto 90% capacity. The autoclave was maintained at 80–1008C for 4–6 h, then cooled to room temperature naturally. The precipitates were collected and washed with absolute ethanol and distilled water in sequence to remove the possible excessive Na and the by-product NaCl. The final products were dried in vacuum at 508C for 4 h. The preparation of the CdSe nanorod was similar to the above procedure except that CdCl2 was used instead of ZnCl2. The reactions were as follows: MCl 2qSeq2Na™Mseq2NaCl (MsZn, Cd)
* Corresponding author. Dept. of Chemistry: Tel.: q86-551-3601589; Fax: q86-551-2819364; E-mail: [email protected]
Fig. 1. XRD pattern of a typical nanorod sample as prepared in ethylenediamine. (a) ZnSe; (b) CdSe.
1387-7003/99/$ - see front matter q 1999 Elsevier Science S.A. All rights reserved. PII S 1 3 8 7 - 7 0 0 3 ( 9 9 ) 0 0 0 1 5 - 5
Tuesday Mar 09 02:21 PM
StyleTag -- Journal: INOCHE (Inorganic Chemistry Communications)
Article: 153
84
W. Wang et al. / Inorganic Chemistry Communications 2 (1999) 83–85
Fig. 2. TEM image of as-prepared sample of: (a) ZnSe nanorod prepared in ethylenediamine; (b) CdSe nanorod prepared in ethylendiamine; (c) ZnSe nanocrystal prepared in pyridine.
X-ray powder diffraction (XRD) data were collected on a Japan Rigaku D/Max gA rotation anode X-ray diffractometer with Ni-filtered Cu Ka radiation. A typical XRD pattern of the as-prepared ZnSe nanorod is shown in Fig. 1a. All peaks in the XRD pattern correspond to the reflections of cubic ZnSe. After refinement, the cell constant as0.567 nm was consistent with the reported value [19]. No impurities were detected. Fig. 1b shows the XRD pattern of the as-prepared CdSe nanorod. All peaks could be indexed as cubic CdSe [20]. After refinement, the cell constant as0.61 nm was in agreement with the reported value [20]. Transmission electron microscopy (TEM) was used to study the morphology and size distribution of the products. Data were recorded on a Hitachi H-800 transmission electron microscope. Fig. 2a shows a typical image of the as-prepared ZnSe nanorod. It clearly shows that the diameters varied from 40 to 70 nm and the lengths from 1.5 to 3 mm. For the CdSe nanorod, which is shown in Fig. 2b, the diameters ranged from 8 to 20 nm, while the lengths ranged from 150 to 500 nm. The quality of the MSe (MsZn, Cd) nanorods was affected by several factors, including the solvent, the temperature, and the length of heating. In our experiment, slightly excessive Na was essential to ensure the quality of the product, so that the Se powder could be completely converted. The possible excessive Na could be removed by absolute ethanol in the washing procedure. Otherwise, if the Se powder is excessive, it is difficult to remove from the product. As to other conditions, a higher temperature or longer time would lead to a larger grain size, while a lower temperature or shorter time would lead to incomplete reaction and low crystallinity. When the temperature was lower than 508C, the reaction could not be initiated. The reaction was carried out at 80– 1008C for 4–6 h, these being the most suitable conditions. In the formation of MSe (MsZn, Cd) nanorods, the solvent played an important role. It was observed that the Se and MCl2 powder slowly disappeared after ethylenediamine was added, and the solution color changed from transparent to brown. This supported the suggestion that amine solvents
Tuesday Mar 09 02:21 PM
dissolved the Se and metal and produced the complex, because they are strong donor ligands having N-chelation [21]. As a result, Se dispersed into solution, its surface area was greatly increased, the activity of the reactants increased, and thus the reaction temperature greatly decreased. So this new solvothermal method differs from the solid state reactions, which always need a high temperature to overcome the large diffusion distance associated with the micrometer-size reactant particles. Furthermore, possibly ethylenediamine bound to and combined Zn2q (Cd2q) and Se in a line due its structure, formed a labile bond and provided simultaneous chemical stability, templated the molecular organization, and thus MSe (MsZn, Cd) nanorods resulted [18,21,22]. When pyridine, which has a weaker N-donor but no line structure like ethylenediamine, was used as solvent instead of ethylenediamine, and the other conditions were the same as those in the experimental procedure, the final product ZnSe grains were spherical as revealed by TEM (Fig. 2c); the diameter varied from 20 to 60 nm, the average size was about 30 nm. When benzene or toluene was selected as solvent, which has no N-chelation, no reactant entered into the solution, no MSe (MsZn, Cd) were detected on the XRD pattern. The reactants remained unreacted, even when the reaction was carried out at a higher temperature (2008C) for a longer time (24 h). The above results further supported the possible growth mechanism of MSe (MsZn, Cd) nanorods.
Acknowledgements This work is supported by the Chinese National Foundation of Natural Science Research and National Nanometer Materials Climbing Program.
References [1] L.E. Brus, Appl. Phys. A 53 (1991) 465. [2] M.A. Kastrer, Phys. Today 46 (1) (1993) 24. [3] Y. Wang, N. Herron, J. Phys. Chem. 95 (1991) 525.
StyleTag -- Journal: INOCHE (Inorganic Chemistry Communications)
Article: 153
W. Wang et al. / Inorganic Chemistry Communications 2 (1999) 83–85 [4] M.G. Bawendi, P.J. Carroll, W.L. Wilson, L.E. Brus, J. Chem. Phys. 96 (1992) 946. [5] I.A. Kudryatsev, J. Opt. Soc. Am. B 10 (1993) 100. [6] A.M. Rao et al., Science 275 (1997) 187. [7] M. Bockrath et al., Science 275 (1997) 1922. [8] ?. Fan, C.M. Lieber, Nature 375 (1991) 769. [9] J. Westwater, D.P. Gosain, S. Tomiya, S. Usui, J. Vac. Sci. Technol. B 15 (3) (1997) 554. [10] K. Suenaga et al., Science 278 (1997) 653. [11] D.S. Bethune et al., Nature 363 (1993) 605. [12] V. Ivanov et al., Chem. Phys. Lett. 223 (1994) 329. [13] T.J. Trentler et al., Science 270 (1995) 1791. [14] S.A. Empedodes et al., Science 278 (1997) 2114.
Tuesday Mar 09 02:21 PM
85
[15] V.Yu. Ivanov, Yu.G. Semenov, M. Surma, M. Godlewski, Phys. Rev. B 54 (1996) 4696. [16] J.E. Bowen Katai, V.L. Colvin, A.P. Alivisatos, J. Phys. Chem. 98 (1994) 4109. [17] X.H. Wu, F.H. Li, S.P. Guo, S.X. Yuan, J. Mater. Sci. Lett. 14 (1995) 110. [18] X. Peng, M.C. Schlamp, A.V. Kadavanich, A.P. Alivisatos, J. Am. Chem. Soc. 119 (1997) 7019. [19] JCPDS No. 37-1463. [20] JCPDS No. 19-191. [21] J.R. Sachleben, W. Wooten, L. Emsley, A. Pines, V.L. Colvin, A.P. Alivistos, Chem. Phys. Lett. 198 (1992) 431. [22] A.K. Verma, T.B. Rauchfuss, S.R. Wilson, Inorg. Chem. 34 (1995) 3072.
StyleTag -- Journal: INOCHE (Inorganic Chemistry Communications)
Article: 153