Nanoparticle production by plasma

doi:10.1016/S0921-5107(99)00422-5

Materials Science and Engineering: B

Volume 68, Issue 1, 20 December 1999, Pages 5-9

https://doi.org/10.1016/S0921-5107(99)00422-5 Get rights and content

Abstract

The paper describes a system designed for magnetic as well as nonmagnetic nanoparticle production for ferrofluids and magneto-rheological fluids. Particles of Fe₃O₄ with a mean diameter of 11.65 nm were obtained by melting the steel and sputtering the molten metal in the argon plasma jet. The thermal decomposition of Fe(Co)₅ in plasma led to the obtaining of magnetic particles with a mean diameter of 12.2 nm. Through thermal decomposition in plasma of Fe 2-etilhexamaleath, amorphous and crystalline graphite particles were obtained with a mean diameter of 6.4 nm, useful for producing conductive magnetic liquids. The vaporization of the steel in argon plasma and in helium plasma respectively, led to obtaining of particles of α-Fe and Fe₃O₄ with diameters in the range 3–90 nm.

Introduction

Magnetic nanoparticles are ferro- and ferrimagnetic particles with diameters between 1 and 100 nm. Their production is of scientific and practical interest. The scientific interest is related to the mechanism that determines their magnetic properties. By means of techniques like Hall microprobe [1], new magnetic properties were observed in comparison with those of the bulk materials [2]. The practical interest results from the utilization of nanoparticles as supports for high density magnetic recording [2], in magnetic detectors [3] and in magneto-optical devices [4], in magnetic liquid production [5] and magneto-rheological fluids [6], etc.

Particles with diameter around 10 nm have desirable magnetic properties [3]. The production of such particles from bulk materials by grinding in the presence of a surfactant is not efficient and in many cases is not possible. Research for nanoparticle production led to two main methods: chemical methods and physical methods. Chemical methods [7], [8], [9] rely on coprecipitation of iron, cobalt and nickel salts in alcalin media, resulting in the formation of ferrimagnetic nanoparticles dispersed in surfactant media. Physical methods [10], [11] rely on vaporization and sputtering of ferromagnetic materials and thermal decomposition of carbides and halogens of ferromagnetics followed by vapour condensation. Particles of controllable purity and composition are obtained. At the same time the physical methods permit the nanoparticle production with pre-established diameter values [3] while the preparation time is ten times shorter than in the case of chemical methods [12]. Devices for nanoparticle production, after adequate adaptations, collect the particles in liquid matrix [13], perform the particle implantation on miscellaneous supports and obtaining of nanostructures useful for producing the magnetic microsystems [14].

Section snippets

Description of installation

The system for producing nanoparticles using plasma and arc methods is schematically shown in Fig. 1. It has a plasma and an electrical arc generator (1), a chamber (2) designed for material processing in plasma and electric arc, the chamber (3) for collecting particles, a vacuum pump (4), a system for recirculating the gas (5), a device for dosage/sputtering of liquids/powders (6), a device for stirring the gases (7), current sources S₁ and S₂, a system for wire movement (8) and a system for

Operation in transferred arc regime

The plasma arc in argon medium is produced directly from the electrode (10), on the sample piece (11) connected through anode (12) to the current source S₁ (Fig. 1). The plasma arc current intensity is I=250 Adc. In argon medium (the flow rate of the plasma jet is 0.5 Nm³·s⁻¹) at the relative pressure 0.030 MPa, the melting of the metal takes place followed by the vaporization and sputtering of the molten metal bath. Particles with a shape close to the spherical one (Fig. 2) are obtained. The

Conclusions

The installation using the transferred plasma arc, plasma jet, TIG and MIG arc respectively produces nanoparticles.

The magnetic particles have dimensions in the range 3–90 nm and graphite particles between 3.1 and 12.1 nm.

The magnetic particles produced by means of transferred arc procedure have the smallest mean diameter (d=11.65 nm with a minimum standard deviation σ=2.14 nm) (in comparison with the other methods).

The magnetic particles obtained by using TIG procedure have the mean diameter d

Acknowledgements

The author thanks the members of the Institute for Complex Fluids, ‘Politehnica’ University of Timisoara, especially to L. Vékás, I. Potencz, M. Raşa (West University of Timisoara), O. Bălău for support given to this paper.

References (20)

S. Gangopadhyay et al.
NanoStructured Mater.
(1992)
I. Nakatani et al.
J. Magn. Magn. Mater.
(1990)
H.S. Lee et al.
J. Magn. Magn. Mater
(1999)
M. Wagener et al.
J. Magn. Magn. Mater
(1999)
M. Wagener et al.
J. Magn. Magn. Mater
(1999)
M. Uda
Nanostructured Mater.
(1992)
I. Bica et al.
Mater. Sci. Eng. B
(1996)
I. Bica
J. Magn. Magn. Mater.
(1999)
K. Wernsdorfer, École Franco-Roumaine de Magnetisme, Oradea 7–15 Sept. (1997)...
R. Morel, V. Dupuis, Ecole Franco-Roumaine de Magnetisme Oradea, 7–15 Sept. (1997)...

There are more references available in the full text version of this article.

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Nanoparticle production by plasma

Abstract

Introduction

Section snippets

Description of installation

Operation in transferred arc regime

Conclusions

Acknowledgements

NanoStructured Mater.

J. Magn. Magn. Mater.

J. Magn. Magn. Mater

J. Magn. Magn. Mater

J. Magn. Magn. Mater

Nanostructured Mater.

Mater. Sci. Eng. B

J. Magn. Magn. Mater.