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Physical Properties of Magnetite Nanoparticles Covered by 11-Mercaptoundecanoic Acid

100%

Timko M., Kopčanský P., Antalik M., Simsikova M., Valusova E., Molcan M., Kováč J.

Acta Physica Polonica A

2012

vol. 121

issue 5-6

1321-1323

We have investigated the magnetic behavior of magnetite nanoparticles covered by the 11-mercaptoundecanoic acid around magnetite core prepared by a standard co-precipitation method. The particles show superparamagnetic behavior at room temperature, with transition to a blocked state at blocking temperature 91 K estimated from zero field cooled and field cooled at 500 Oe experiment. The hysteresis loop measured at 293 K showed magnetization 32.8 emu/g at 50 kOe without any coercivity. The mean particle size (7.1 nm) was determined by fitting a magnetization curve obtained at 295 K assuming a log-normal size distribution.

Magnetodielectric Properties of Transformer Oil Based Magnetic Fluids

84%

Timko M., Kopcansky P., Molcan M., Tomco L., Marton K., Molokac S., Rybar P., Stoian F., Holotescu S., Taculescu A.

Acta Physica Polonica A

2012

vol. 121

issue 5-6

1253-1256

This contribution is devoted to study of dielectric and magnetodielectric properties in transformer oil based magnetic fluid. The dielectric permittivity and their anisotropy at various mutual orientation electric (50 Hz) and magnetic field were shown at the different volume concentrations of nanoparticles at room temperature. The linear increase of dielectric constant with volume concentration was confirmed which is in good agreement with the theoretical Maxwell prediction. The dielectric anisotropy factor g(B, ω) is very close to g=1. The values of permittivity increased with the increase of volume fraction of magnetite nanoparticles. The highest value of anisotropy characterized by deviation of permittivity Δε=ε_{∥} - ε_{⊥} was found for the highest volume concentration which could mean that no aggregation of magnetite nanoparticles had appeared.

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2 Acta Physica Polonica A

2 2012

2 Molcan M.

2 Timko M.

1 Antalik M.

1 Holotescu S.

1 Kopcansky P.

1 Kopčanský P.

1 Kováč J.

1 Marton K.

1 Molokac S.

1 Rybar P.

1 Simsikova M.

1 Stoian F.

1 Taculescu A.

1 Tomco L.

1 Valusova E.

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Physical Properties of Magnetite Nanoparticles Covered by 11-Mercaptoundecanoic Acid

Magnetodielectric Properties of Transformer Oil Based Magnetic Fluids