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1

Electro-Rheological Properties of Transformer Oil-Based Magnetic Fluids

100%

Paulovičová K., Tóthová J., Rajňák M., Timko M., Kopčanský P., Lisý V.

Acta Physica Polonica A

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2017

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vol. 131

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issue 4

1141-1143

EN

The aim of this work was to study rheological behavior of nanofluids affected by electric field and temperature. We used transformer oil-based magnetic fluids, the suspensions of permanently magnetized colloidal particles (Fe_3O_4) coated by a stabilizing surfactant and immersed in transformer oil. The rheological characterization of transformer oil-based magnetic fluid was performed using the rotational rheometer MCR 502 in the shear rate from 10 to 1000 s¯¹.The strength of electric field was changed in the interval 0-6 kV cm¯¹. The flow curves and viscosity functions detected at three different temperatures 25, 50, and 75°C disclose rheological characteristics of samples, first of all the viscosity growth under increasing strength of electric field.

2

A.C. Susceptibility Measurements under High Pressure up to 2.0 GPa

100%

Średniawa B., Duraj R., Zach R., Guillot M.

Acta Physica Polonica A

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2000

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vol. 97

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issue 5

917-920

EN

A newly developed pressure setup for a.c. susceptibility measurements in the pressure range up to 2.0 GPa is presented; the temperature domain extends from 77 to 450 K. The steel pressure chamber contains the sample located at the center of a set of three compensated pick-up coils and the pressure and temperature sensors. Either alcohol or extraction naphtha is used as the liquid pressure transmitting medium. The (P,T) magnetic phase diagram of (Fe_{0.975}Ni_{0.025})_{2}P system in the pressure range up to 2.0 GPa is reported.

3

SQUID Magnetometry and Magneto-Optics of Epitaxial EuSe

100%

Rumpf K., Granitzer P., Kellner W., Kirchschlager R., Janecek S., Pascher H., Krenn H.

Acta Physica Polonica A

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2004

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vol. 105

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issue 6

621-629

EN

The complicated (H,T)-magnetic phase diagram of EuSe is caused by the critical balance between nearest and next nearest neighbour exchange interaction (J_{NN}=0.119 K and J_{NNN}=-0.1209 K) and leads to various spin arrangements NNSS..., NSN..., NNS, NNN... [NS denotes opposite ferromagnetic order in adjacent (111) planes]. Beside the subtle local exchange of 5d-t_{2g} electrons and localized holes with neighbouring Eu-4f spins, obviously also the strain status influences the occurrence of these different phases. We investigate the magnetic ordering phenomenon in a strained 2.5 μm EuSe film on BaF_2 substrate by SQUID magnetometry and magneto-optics like spectral Faraday- and Kerr-effect measurements for temperatures from 2 K up to 200 K and for magnetic fields up to 5 T. The magneto-optical probe monitors the local environment of the photoexcited electron-hole pair, called magnetic exciton, located within a ferromagnetic surrounding (photoinduced magnetic polaron), whereas the integral magnetization measured by SQUID is most sensitive to long-range magnetic ordering. In spite of the dissimilarity of measurement techniques we find an influence of the long-range magnetic order (e.g. of the NNS- or NNN-matrix) on the non-resonant Kerr reflection. The complementarity of SQUID and magneto-optical methods is stringent only in the (resonant) spectral regime, where magnetic polarons are formed.

4

Viscosity Dependence of a Magnetic Fluid Nanoparticles Concentration

100%

Tóthová J., Kováč J., Kopčanský P., Rajňák M., Paulovičová K., Timko M., Józefczak A.

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vol. 126

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issue 1

278-279

EN

In this work we have studied the effect of temperature on the viscosity of magnetic fluids (MFs) based on the transformer oil ITO 100. The volume concentration of suspended magnetic particles (MPs) changed from 0.25 to 1%. Rheological characterization of MFs was performed using a vibroviscometer at working frequency of 30 Hz. The temperature dependence of the viscosity was measured in the temperature range from 20 up to 50 °C. The magnetization of different concentrations of MPs in MFs was determined by using the vibrating sample magnetometer.

5

Magnetic Study of Nanocrystalline TiB₂, TiC, B₄C Powders Doped to AISI 316L Austenitic Steel

88%

Bodziony T., Kaczmarek S., Biedunkiewicz A., Leniec G., Figiel P.

Acta Physica Polonica A

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2017

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vol. 132

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issue 1

62-68

EN

The investigations into ferromagnetic resonance and magnetic susceptibility of nanocrystalline TiB₂, TiC, and B₄C powders (Ti-B-C system) doped to AISI 316L austenitic steel with different amounts (3 vol.%, 5 vol.% and 7 vol.%) have been carried out. The ferromagnetic resonance spectra were recorded in the temperature range from helium up to room temperature. The three tested composite samples contain a number of magnetic phases in different proportions. They reveal a structure originating from several different complex magnetic centers. The composites revealed such magnetic phenomena as paramagnetism, (anti)ferromagnetism, and superparamagnetism. Magnetic susceptibility investigations supported the ferromagnetic resonance studies and their analysis. Magnetic properties of the TiB₂, TiC, B₄C powders doped to AISI steel may play important role in further possible applications of these composite systems.

6

Changes of thermal, mechanical and magnetic properties of an amorphous Fe80Cr5B15 alloy during magnetic and structural phase transitions

75%

Kamasa P., Myśliński P.

Open Physics

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2006

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vol. 4

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issue 2

178-186

EN

Thermal, mechanical and thermomagnetic properties associated with the magnetic and structural transition of an amorphous Fe80Cr5B15 alloy are described. The investigation was carried out in a simultaneous dilatometric and thermomagnetic experiment. An anomaly of the thermal expansion coefficient at the Curie point and a change in mechanical properties just before the onset of crystallization are observed. The results are compared with the thermal behavior obtained by differential scanning calorimetry.

Refine search results

Electro-Rheological Properties of Transformer Oil-Based Magnetic Fluids

A.C. Susceptibility Measurements under High Pressure up to 2.0 GPa

SQUID Magnetometry and Magneto-Optics of Epitaxial EuSe

Viscosity Dependence of a Magnetic Fluid Nanoparticles Concentration

Magnetic Study of Nanocrystalline TiB₂, TiC, B₄C Powders Doped to AISI 316L Austenitic Steel

Changes of thermal, mechanical and magnetic properties of an amorphous Fe80Cr5B15 alloy during magnetic and structural phase transitions