Skupina Nanomateriálov a Aplikovaného Magnetizmu

Riešiteľský kolektív: Ivan Škorvánek Jozef Kováč Jozef Marcin Peter Kulík Jana Turčanová (PhD)

Riešená problematika 2007

magneticky mäkké a magneticky tvrdé nanokryštalické zliatiny pripravované z amorfných prekurzorov

nové materiály pre magnetickú refrigeráciu magnetické nanočastice na báze Au, Ag a prechodových

kovov

Grantové projekty (2007)

• VEGA 2/7169 Nové nanokryštalické magneticky mäkké a magneticky tvrdé materiály so zlepšenými funkčnými vlastnosťami   (2007-2009)

• APVV-0413-06 (s FÚ SAV) Komplexné kovové zliatiny (2007-2009)

• COST P17 - Electromagnetic Processing of Materials, Improvement of functional properties of Fe- and Co-based nanocrystalline magnetic materials by heat treatment in magnetic field (2006-2009)

• Cex – NANOSMART Centrum Excelentnosti SAV pre Nanoštruktúrne Materiály (2007 – 2010)

CC Publikácie 20071. I. Škorvánek, J. Kováč, J. Marcin, P. Švec and D. Janičkovič, Magnetocaloric effect in

amorphous and nanocrystalline Fe81−xCrxNb7B12 (x = 0 and 3.5) alloys, Materials Science and Engineering: A 449–451 (2007) 460–463,

2. P. Baláž, L. Takacs, E. Godočíková, I. Škorvánek, J. Kováč and W.S.Choi, Preparation of nanosized antimony by mechanochemical reduction of antimony sulphide Sb2S3

Journal of Alloys and Compounds 434–435 (2007) 773–775 3. M. Deanko, M. Paluga, D.M. Kepaptsoglou, D. Muller, P. Mrafko, D. Janičkovič, E.

Hristoforou, I. Škorvánek, P. Švec, Pecularities of electrical resistivity during transformations in amorphous and nanocrystalline alloys, Journal of Alloys and Compounds 434–435 (2007) 248–251

4. I. Škorvánek, J. Marcin, J. Turčanová, M. Wojcik, K. Nesteruk, D. Janičkovič, P. Švec Field induced anisotropy and stability of soft magnetic properties towards high

temperature in Co-rich nanocrystalline FeCoNbB alloys, Journal of Magnetism and Magnetic Materials 310 (2007) 2494–2496

5. E. Godočíková, P. Baláž, L. Takacs, V. Šepelák, I. Škorvánek, E. Gock, Sb/FeS nano-composite prepared by mechanochemical reduction, Kovové Materiály, 45 (2007) 99-104

6. P. Kollár, D. Olekšákova, J. Fuzer, J. Kováč, S. Roth, K. Polanski, The magnetic properties of powdered and compacted microcrystalline permalloy, Journal of Magnetism and Magnetic Materials 310 (2007) 2609–2611

7. A.Zeleňáková, D.Olekšáková, J. Degmová, J. Kováč, P. Kolár, M. Kusý, P. Sovák Structural and magntic properties of mechanically alloyed FeCo powders, Journal of Magnetism and Magnetic Materials. Vol. 316, no. 2 (2007), p. e519-e522

Soft Magnetic Fe(Cr)-based alloys for magnetocaloric applications at RT

250 300 350 400

TC

dM/d

T

Temperature (K)

TC

200 300 400 500 600 700 800 900 1000 1100

0

20

40

60

80 Fe81

Nb7B

12

Fe77.5

Cr3.5

Nb7B

12

M

agne

tizat

ion

(Am

2 /kg)

Temperature (K)

Set of M(T) curves for annealed Fe81Nb7B12

0 100 200 300 400 500 600 700 800 9000

20

40

60

80

100

T = 5 K

T = 470 K

T = 300 K

Fe81Nb7B12

M (

Am

2 kg-1)

0H (mT)

Magnetic Entropy Change

250 300 350 400 4500,0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

S (

JK-1kg

-1)

Temperature (K)

Fe81

Nb7B

12

as-quench 743 K/1 h 773 K/1 h

Fe77.5

Cr3.5

Nb7B

12

as-quench 723 K/1 h 800 K/1 h

Set of M(T) curves for Pr13Fe87

0 1 2 3 4 5 60

50

100

150

mag

netiz

atio

n (A

m2 kg

-1)

0H (T)

235

350

T = 5K

Pr13

Fe87

Magnetic Entropy Change for Pr13Fe87

240 260 280 300 320 3400

2

4

6

Sm (

JK-1kg

-1)

temperature (K)

5 T

4 T

3 T

2 T

1 T

Pr13

Fe87

Effect of heat treatment in longitudinaland transverse field vs Co-content in

(Fe1-xCox)81Nb7B12 (annealing at 773 K/1h)

-100

0

100

-3 -2 -1 0 1 2 3

-100

0

100

-3 -2 -1 0 1 2 3

x=0.5

x=0.66

Mag

netiz

atio

n (A

m2 /k

g)

x=0.75

ZF LF TF

H (kA/m)

x=1.0

Hard Magnetic FePtNbB-based nanocrystalline alloys

-6 -4 -2 0 2 4 6-80

-60

-40

-20

0

20

40

60

80

M (

Am

2 /kg)

FePtNbB 1279500°C/1h + 600°C/30 min

measured at 300 K

Hc FePtNbB / Hc FeNiNbB ~ 106 !!!

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