INSTITUTE OF PHYSICS PUBLISHING JOURNAL OF PHYSICS D: APPLIED PHYSICS J. Phys. D: Appl. Phys. 39 (2006) 2212–2219 doi:10.1088/0022-3727/39/10/033 Characteristics of FeCo nano-particles synthesized using plasma focus T Zhang 1 , K S Thomas Gan 2 , P Lee 1 , R V Ramanujan 2 and R S Rawat 1 1 National Institute of Education, Nanyang Technological University, Singapore 637616, Singapore 2 School of Material Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore E-mail: rsrawat@nie.edu.sg Received 13 January 2006, in final form 26 February 2006 Published 5 May 2006 Online at stacks.iop.org/JPhysD/39/2212 Abstract In our recent investigation, a 3.3 kJ Mather type plasma focus was used to synthesize FeCo nano-particles. The tops of the anodes normally used were replaced by the materials to be synthesized using different numbers of focus shots. It is observed that the characteristics of the nano-particles depend not only on the numbers of focus shots but also on the angular position of the mounted sample. SEM results show that the size of the nano-particles is smaller when the sample is mounted at a bigger angular position. The size of the particles increases linearly with the increase in the number of focus shots. EDX shows that the FeCo nano-particles are stoichiometric. The magnetic properties measured using a vibrating sample magnetometer identify the soft magnetic nature of the FeCo nano-particles. The saturation magnetization has been found to increase in samples prepared with a higher number of focus shots using repetitive plasma focus NX2. 1. Introduction The current curiosity about nano-particles has been phenome- nally increasing because of their interesting electronic, optical, magnetic, mechanical and chemical properties [1]. Interest in these materials is motivated by the fact that the small grain size gives the nano-particles unique physical and chemical proper- ties which are totally different from those of their bulk counter- parts. The metallic nano-particles of magnetic materials draw special attention owing to their notable uses and applications in ultrahigh density data storage, gas sensor, toner material for high quality colour copiers and printers, new generation electric motors and generators, environment friendly refriger- ants and biomedicine [1–3]. Each of the applications requires that the magnetic nano-particles have different properties [2]. Hence, the synthesis of magnetic nano-particles in a controlled manner is still a real challenge for their practical usages. Sev- eral chemical and physical methods such as sol–gel, ion im- plantation and sputtering, spray and laser pyrolysis, chemical and physical vapour deposition and pulsed laser ablation de- position (PLAD) have been employed for synthesis of nano- particles [4–8]. In particular, molecular beam epitaxy, triode sputtering, ultrasound-assisted electrochemistry, dc magnetron sputtering, laser ablation and e beam were also used to deposit magnetic particles [8–11] and thin films [12–20]. Compared with these methods, plasma focus, as a copious source of energetic ions, has advantages such as high deposition rate, energetic deposition process and possible deposition under reactive background gas pressures. The deposition process in dense plasma focus (DPF) is done through heating, compressing and ionizing the filling gas to form plasma. The plasma then disintegrates due to plasma instabilities which generate energetic ions and relativistic electrons. The energetic electrons along with plasma jet are responsible for the ablation of the anode material and the ablated material is deposited on the substrate. The thin film deposition mechanism in a plasma focus device is described in detail by Soh et al [21]. In our present investigation, a single shot plasma focus machine was used to synthesize FeCo magnetic nano-particles and they were characterized using different methods including scanning electron microscopy (SEM), energy dispersive x-ray (EDX) spectroscopy, x-ray diffraction (XRD) and vibrating sample magnetometry (VSM). 0022-3727/06/102212+08$30.00 © 2006 IOP Publishing Ltd Printed in the UK 2212