Journal of Alloys and Compounds 505 (2010) 352–356 Contents lists available at ScienceDirect Journal of Alloys and Compounds journal homepage: www.elsevier.com/locate/jallcom Synthesis and characteristic of carbon-encapsulated ferronickel nanoparticles by detonation decomposition of doping with nitrate explosive precursors Luo Ning a,∗ , Li Xiaojie a , Sun Yuling b , Wang Xiaohong a a State Key Laboratory of Structural Analysis for Industrial Equipment, Dalian University of Technology, Dalian 116024, China b Artillery Academy of PLA, Hefei 230031, China article info Article history: Received 11 January 2010 Received in revised form 10 May 2010 Accepted 14 May 2010 Available online 18 June 2010 Keywords: Composite nanoparticles Nanostructure Detonation synthesis Transmission electron microscopy Magnetic properties abstract Synthesizing carbon-encapsulated ferronickel nanoparticles was developed by a detonation method. The composite precursors were ignited in the nitrogen in closed explosion vessel. These composite nanopar- ticles were characterized with transmission electron microscope, energy-dispersive X-ray spectrometer, X-ray diffraction, X-ray fluorescence, Raman spectroscopy and magnetic measurement. Results indicated that carbon-encapsulated ferronickel nanoparticles with diameters ranging from 10 to 50 nm were pro- duced and the composite nanoparticles were with a core–shell structure. The composite nanoparticles were synthesized with the yield about 10–15% one time. © 2010 Elsevier B.V. All rights reserved. 1. Introduction The graphite carbon shell protects the metallic core against oxi- dization and further agglomeration to form bigger crystallites. Saito [1,2] revealed that rare-earth metals with low vapor pressure (Sc, Y, La, Ce, Pr, etc.) were encapsulated in the form of carbides, while the volatile Sm, Eu and Yb metals showed no evidence of being wrapped in graphitic carbon by using electric arc discharge method. So far, a number of strategies for preparing CEMNPs have been developed, including modified arc discharge [3,4], chemical vapor deposition (CVD) [5], high-temperature heat treatment [6], ion- beam sputtering methods [7] and heat-induced explosion [8], etc. Specifically, Fe, Ni and Co have received the most interest due to their ferromagnetic properties and their unique catalyzing ability [9–11]. High level energy consumption and intricate uses of various facilities of the methods hinder the preparation of carbon- encapsulated metal nanocrystals in high yield. Accordingly, using detonation method [12–14] to synthesizing carbon-encapsulated metal nanoparticles (CEMNPs) is being an effective way and subse- quent characterization of the properties of these nanoparticles are currently being actively investigated. Currently, only a few studies have dealt with carbon-encapsulated ferronickel alloy nanomate- rials. Therefore, studies investigating a more efficient technique ∗ Corresponding author. Tel.: +86 18940935017; fax: +86 041184708307. E-mail addresses: roling8080@163.com (N. Luo), dymat@163.com (X.J. Li). to encapsulate metal nanoparticles with a core–shell structure are required. In this work, a simple and efficient technique for prepar- ing carbon-encapsulated ferronickel composite nanoparticles was described. The detonation of composite explosive precursors not only produced powerful shock waves but also provided elemental building blocks and an unique high-pressure and high-temperature physical environment for the construction of various nanostruc- tures [15]. Due to their potential application for magnetic materials, biological materials and catalyzers, graphite-encapsulated alloy composite nanoparticles were synthesized by detonation decom- position of explosive precursors doping with a soluble nitrate (metal source) and acetone/cyclonite (carbon source). 2. Experimental The detonation synthesis of nanoparticles were performed in an explosion vessel as described in the previous work [16,17]. To synthesize ferronickel@C nanoparti- cles, iron nitrate and nickel nitrate (Fe(NO3)3·9H2O, Ni(NO3)2·6H2O) were selected as metal source materials for explosive precursors, together with carbon source materials such as pentaerythritol tetranitrate/cyclonite. The metallic sources were mixed with a given mole ratio of 2:1 and 1:1. All the chemical reagents used in this study were analytical grade. In a typical experimental procedure, the as-prepared composite precursors were placed into the closed explosion vessel about 0.4 m 3 capacity filling with nitrogen gas. After detonation reaction, the black powders were scraped from the inner explosion vessel. The powders were washed with absolute ethyl alcohol solution and then dried up in air. The composite nanoparticles were synthesized with the yield about 10–15% one time, that is, it takes one kilograms of precursors to make 100–150 gram of the composite nanoparticles. Transmission electron microscope (TEM, operating at 200 kV) was used to reveal the morphology and microstructure of the nanoparticles. The TEM samples were 0925-8388/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.jallcom.2010.05.181