Journal of Alloys and Compounds 484 (2009) 341–346 Contents lists available at ScienceDirect Journal of Alloys and Compounds journal homepage: www.elsevier.com/locate/jallcom Synthesis and characterization of 3C and 2H-SiC nanocrystals starting from SiO 2 , C 2 H 5 OH and metallic Mg Ting Li, Liqiang Xu ∗ , Liancheng Wang, Lishan Yang, Yitai Qian ∗ Key Laboratory of Colloid and Interface Chemistry (Shandong University), Ministry of Education, Jinan 250100, PR China article info Article history: Received 3 February 2009 Received in revised form 8 April 2009 Accepted 19 April 2009 Available online 24 April 2009 Keywords: Silicon carbide Nanostructured materials Transmission electron microscopy X-ray diffraction abstract Silicon carbide (3C-SiC) nanocrystals were prepared starting from SiO 2 ,C 2 H 5 OH, and metallic Mg in an autoclave at 200 ◦ C. X-ray diffraction patterns of the sample can be indexed as the cubic phase of SiC with the lattice constant a = 4.357 Å, in good agreement with the reported value (JCPDS card no. 29- 1129; a = 4.359 Å). Transmission electron microscopy images show that the product mainly composed of nanowires with diameters in the range of 10–30nm and lengths up to tens of micrometers; High- resolution transmission electron microscopy images reveal that these 3C-SiC nanowires grow along [1 1 1] direction; As polyvinylpyrrolidine was added into the above reactant system, the final products obtained at 180 ◦ C were mixed 3C and 2H-SiC flakes. Thermal gravimetric analysis curves reveal that these two samples have thermal stability below 800 ◦ C, and room-temperature photoluminescence spectrum of the 3C-SiC sample show a strong emission peak centered at 403 nm. © 2009 Elsevier B.V. All rights reserved. 1. Introduction Silicon carbide (SiC) is a semiconducting material with wide band gap (2.39 ev for 3C-SiC and 3.33 ev for 2H-SiC at room tem- perature) [1], which has high mechanical strength, high thermal conductivity, high breakdown electric field [2]. These unique phys- ical and electronic properties make SiC a suitable material for the fabrication of electronic devices operating at high-temperature, high power, high frequency and in harsh environments [3]. Various methods have been developed for the synthesis of SiC nanocrystals, such as the carbothermal reduction reaction [4,5], chemical vapor reaction [6], sol–gel [7,8], self-propagating high temperature synthesis [9], autoclave route [10–15] and so on. Among these methods, prepare SiC in an autoclave is one of the effective routes at low temperature, such as the reactant sys- tems: SiCl 4 -Na-C [10] or SiCl 4 -Na-C 6 Cl 6 [11] at 600 ◦ C, SiCl 4 -Na-CCl 4 at 400 ◦ C [12], SiCl 4 -Na-K-CBr 3 H at 130 ◦ C [13], or sulfur-assisted reduction route (Si-S-Na-C 2 Cl 4 ) at 130 ◦ C [14]. Moreover, 2H-SiC nanoflakes also have been prepared in an autoclave at 180 ◦ C [15]. In the previous reports [13–15], SiCl 4 and Si were chosen as sili- con sources, C 2 Cl 4 and CBr 3 H were used as carbon sources, Na–K alloy and Na were used as reductant. Among the silicon precursors used to synthesize SiC, SiO 2 is widely used due to the low cost, such as SiO 2 -carbon black at 1200–1600 ◦ C [4,5], Si-SiO 2 -C 3 H 6 at 1250 ◦ C [6], and so on. However, there are fewer reports about the ∗ Corresponding authors. Tel.: +86 531 8836 6280; fax: +86 531 8836 6280. E-mail address: xulq@sdu.edu.cn (L. Xu). synthesis of SiC by using SiO 2 as silicon sources at relative low tem- perature (below 1000 ◦ C). In the current study, SiO 2 was used as silicon source, C 2 H 5 OH as carbon source, and metallic Mg substi- tute Na–K alloy and Na was used as reductant. The advantage of this route is that parlous or corrosive reagents have been avoided. In this study, 3C-SiC nanocrystals were prepared starting from SiO 2 ,C 2 H 5 OH, and Mg at 200 ◦ C; As polyvinylpyrrolidine (PVP) was added into the above reactant system, the final product obtained at 180–200 ◦ C were mixed 3C and 2H-SiC. The yield of 3C-SiC sample prepared at 200 ◦ C was about 23%, calculated based on the amount of SiO 2 . The yield of mixed 3C and 2H-SiC sample prepared at 180 ◦ C was about 57%. Low temperature and cheap raw materials make it possible for large scale synthesis of SiC nanocrystals. The reaction can be described as follows: SiO 2 + C 2 H 5 OH + 3Mg = SiC + 3MgO + C + 3H 2 (1) Thermal gravimetric analysis (TGA) curves of the product reveal that the as-prepared samples have high thermal stability below 800 ◦ C. Room-temperature photoluminescence (PL) spectrum of the 3C-SiC sample exhibit a strong emission peak centered at 403 nm. 2. Experimental 2.1. Preparation of 3C-SiC nanocrystals In a typical process, 10 ml C2H5OH (analytical grade), 3.6 g SiO2 (analytical grade, Shanghai Chemical Reagents Co.), and 1.5g Mg (Tianjin damao Chemical Reagents Co., 99%) were loaded into a stainless steel autoclave with a capacity of about 20 ml. The autoclave was sealed and maintained at 200 ◦ C for 10h, then cooled to room temperature naturally. The raw products in the autoclave were collected and washed 0925-8388/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.jallcom.2009.04.096