Soft magnetic materials, from statics to radiofrequencies - - PowerPoint PPT Presentation

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Soft magnetic materials, from statics to radiofrequencies - - PowerPoint PPT Presentation

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Soft magnetic materials, from statics to radiofrequencies Victorino Franco Sevilla University. Spain Current trends in Confirmed invited speakers Magnetic Refrigeration J. I. Betancourt Reyes (UNAM); E.H. Bruck (Delft University of

slide-1
SLIDE 1

Soft magnetic materials, from statics to radiofrequencies

Victorino Franco Sevilla University. Spain

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SLIDE 2

Current trends in Magnetic Refrigeration

  • Magnetocaloric materials:

– Giant magnetocaloric materials – Second order phase transition materials – Nanostructured materials – Multiphase materials and composites

  • Modeling the magnetocaloric effect
  • Experimental techniques for the

characterization of magnetocaloric materials

  • Magnetic refrigeration devices
  • Related topics on thermomagnetic energy

harvesting

Confirmed invited speakers

  • J. I. Betancourt Reyes (UNAM);
  • E.H. Bruck (Delft University of Technology);
  • G.P. Carman (UCLA);
  • A. Fujita (Tohoku University);
  • Z.W. Liu (South China University of Technology);
  • V.K. Pecharsky (Ames Laboratory);
  • M.H. Phan (University of South Florida);
  • A. Rowe (University of Victoria);
  • J. L. Sánchez Llamazares (IPICYT);
  • K. Skokov (Technische Universität Darmstadt);
  • K. G. Suresh (IIT Bombay).

http://www.mrs.org/imrc-2013-cfp-7b/

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

slide-3
SLIDE 3
  • Introduction

– 5 key questions in a nutshell: What, which, where, when, why

  • Optimization of soft magnetic properties

– Coercivity: disorder is not a bad quality all the time. – Frequency response: losses – Do we always need the highest permeability?: high frequency power conversion

  • Example of sensor application: GMI

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

slide-4
SLIDE 4

Soft magnets in the global market

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

JMD Coey, J. Alloy. Compd. 326 (2001) 2

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SLIDE 5

Where are they used?

  • Magnetic shielding (passive)
  • Flux concentrators
  • Sensors, anti-theft systems
  • Power conversion

– Transformers, inductors – Motors, generators

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

Tesla car; induction motor

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SLIDE 6

What we need

  • High saturation magnetization

– composition

  • Low coercivity

– microstructure

  • High Curie temperature
  • High permeability (most of the times)
  • Frequency response  low losses

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

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SLIDE 7

Evolution of soft magnetic materials

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

JMD Coey, Magnetism and Magnetic Materials, Cambridge University Press, 2010 M.A. Willard, M. Daniil, K.E. Kniping, Scripta Mater. 67 (2012) 554

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SLIDE 8

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

M.E. McHenry, M.A. Willard, D.E. Laughlin, Prog Mater Sci 44 (1999) 291

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SLIDE 9

Warning: The importance of the demagnetizing field

  M H

  

appl demag demag

H H H H NM

a appl

M H   ( ) ( ) (1 )

a appl a a a

H H NM H N H H N            

(1 )     

a

N

Material: Internal field “intrinsic” susceptibility Measurement: Applied field Apparent susceptibility

1  

a

N

If N or the susceptibility are large,

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

slide-10
SLIDE 10
  • Small applied fields for samples with high

permeability

  • M(T) for different

applied fields

(1 )     

a

N

(1 )

appl appl appl

H H NM H N N H      1  

a

N

150 200 250 300 350 1 2 3 10 15 20 25 30

M (memu) T (ºC)

field (Oe): 1 10 100 1000 5000 10000

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

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SLIDE 11

OPTI MI ZATI ON OF COERCI VI TY

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

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SLIDE 12

Domain wall pinning and defects

  • Potential energy E of the

wall (per area unit):

– Random function of position

  • Local stresses
  • Defects
  • 180º domain wall of area A

moving a distance x

– Magnetization change from

  • M to M

– Energy change

  • Equilibrium:

( 2 ) 2

i i

d E H Mx dx dE H M dx     

2

i

H Mx  

R.C. O’Handley, “Modern magnetic materials: principles and applications”. John Wiley and Sons, 1999

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

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SLIDE 13

Grain size and coercivity

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

  • G. Herzer, J. Magn. Magn. Mater. 112 (1992) 258

Reduce defects to decrease coercivity

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SLIDE 14

Grain size and coercivity

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

  • G. Herzer, J. Magn. Magn. Mater. 112 (1992) 258
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SLIDE 15

SI MPLE ANALOGI ES TO EXPLAI N THE SMALL CRYSTAL SI ZE RANGE

(AKA: understanding the random anisotropy model without formulae)

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

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SLIDE 16

Who will feel the irregularities?

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

Floor of Colegiata de Santa María de Arbas, León (Spain)

The key is the different length scale (irregularities vs. shoes)

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SLIDE 17

Refrigerator magnets

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

Side view Reverse side Front (decorated side) Field lines Domains

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SLIDE 18

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

Refrigerator magnets

Side view Reverse side Front (decorated side) Field lines Domains

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SLIDE 19

Characteristic lengths

  • Two characteristic lengths along the direction of

movement:

– Substrate (separation between stripes) – Mobile piece

  • Parallel orientations:

– Lsubstr. ~ separation between stripes – Lmobile ~ Lsubstr. – Movement significantly alters the energy of the system

  • Perpendicular orientations:

– Lmobile ~ size of the mobile piece – Lsubstr.< < Lmobile – We cannot detect, macroscopically, energy differences

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

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SLIDE 20

Two different correlation lengths

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

Correlation lengths structural magnetic

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SLIDE 21

Let’s quantify

  • Select randomly the
  • rientation of particles
  • Choose magnetic

correlated areas of different sizes

  • Displace the correlated

area thoughout the “sample”

  • Measure the dispersion

in energy

  • Average multiple times

Victorino Franco. European School of Magnetism. Cargèse (France) 2013 2 4 6 8 10 0.0 0.2 0.4 0.6 0.8 1.0

Emax-Emin (a.u.) # of correlated particles (x1000)

1000 10000 0.03 0.04 0.05 0.06 0.07 0.08 0.09

1 N 

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SLIDE 22

Random anisotropy model

* 3 * 4 6 *3

/ K K N L N l K K l A         

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

  • K. Suzuki, in Handbook of Advanced Magnetic

Materials, Springer, 2006, pp. 339-373

  • G. Herzer, J. Magn. Magn. Mater. 112

(1992) 258

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SLIDE 23

Finemet alloy

  • Composition: Fe73.5Si13.5B9Cu1Nb3
  • Magnetically softer after nanocrystallization

– Two phase nature – Influence of the addition of Cu & Nb

  • Segregation of Cu-rich clusters
  • Rejection of Nb at the crystal interfaces
  • Importance

– Technological applications (magnetic sensors, anti-theft systems, etc.) – Fundamental studies in magnetism

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

25 nm

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SLIDE 24

Production of amorphous alloys I : melt spinning

Video courtesy of Joseph F . Huth III MAGNETICS, div. of SPANG & CO.

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

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SLIDE 25

Crystallization behavior

Fe76Si10.5B9.5Cu1Nb3

  • Devitrification takes

place in two main stages

– 1st exotherm: -Fe,Si – 2nd exotherm: Fe2B, ...

  • Compositional effects

– Substitution of Fe by Cr

  • r Mo
  • Enhancement
  • f

the stability of the amorphous phase

700 800 900 1000

dH/dt ( kW / kg ) T ( K )

0.0 0.1

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

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SLIDE 26

Microstructure

25 nm

Amorphous Nanocrystalline Fully crystallized

40 60 80 100

2  (º)

40 60 80 100

2 (º)

40 60 80 100

2 (º)

25 nm 350 nm

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

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SLIDE 27

Thermomagnetic measurements

400 600 800 1000 20 40 60 80 100 120 140 b a c

M ( a. u. ) T ( K )

  • As cast sample (a):

– Tc(Amorphous) – Onset of Crystallization – Tc(Fe,Si)

  • Nanocrystalline (b,c):

– Tc(residual amorphous) – Tc(Fe,Si)

  • Fully crystallized (d):

– Tc(Fe,Si) (change in % Si) – Tc(Fe2B) – Tc(boride type phase)

400 600 800 1000 20 40 60 80 100 120 140 a

M ( a. u. ) T ( K )

400 600 800 1000 20 40 60 80 100 120 140 d b a c

M ( a. u. ) T ( K )

V . Franco, C.F . Conde, and A. Conde, J. Magn. Magn. Mater. 185 (1998) 353

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

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SLIDE 28

Coercivity

400 600 800 1000 10 20 30 40 2000 4000

HC ( A / m ) Ta ( K )

Stress relaxation Nanocrystallization onset Averaging of anisotropy 2nd crystallization stage

V . Franco, C.F . Conde, A. Conde, L.F . Kiss, J. Magn. Magn. Mater. 215 (2000) 400

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

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SLIDE 29

High temperature soft magnetic nanocrystalline alloys

  • Can we keep the soft magnetic

properties at higher temperatures? Limitations:

– Microstructural evolution – Magnetic softness

  • Individual nanoparticles

– Superparamagnetism

  • No hysteresis
  • Overlapping of magnetization curves
  • Limited by anisotropy energy (TB)
  • Nanocrystalline alloys?

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

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SLIDE 30

Superparamagnetism in nanocrystalline alloys

  • Low temperature: blocked state (ferromagnetic

matrix)

  • High temperature: superparamagnetic relaxation

– Not controlled by blocking temperature, but by the ferromagnetism of the matrix

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

400 600 800 1000 20 40 60 80 100 nanocrystalline as cast

M ( a. u. ) T ( K )

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SLIDE 31

Superparamagnetic relaxation

  • Requisites:

– No hysteresis – Overlapping of magnetization curves

  • Limited by:

– Anisotropy energy (TB) – Decoupling of the grains – 2nd crystallization stage

0.0 0.5 1.0 1.5 2.0 0.0 0.5 1.0

615K 630K 648K 670K 687K

M(T)/Ms (T) Ms(T) · H / T

V . Franco, C.F . Conde, A. Conde, L.F . Kiss, J. Magn. Magn. Mater. 215 (2000) 400

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

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SLIDE 32

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

Cr-containing Finemet alloy

  • Thermal stability is

enhanced

  • Cryst. volume fraction

is reduced

  • Smaller mean grain

size

800 850 900 950 1000

0.1

T (K)

Fe63.5Cr10Si13.5B9Cu1Nb3

V . Franco et al., J. Appl. Phys. 90 (2001) 1558

slide-33
SLIDE 33

Thermomagnetic properties

300 400 500 600 700 800 900 1000 0.0 0.2 0.4 0.6 0.8 1.0 c b a

M (a.u.) T (K)

  • Significant

reduction of Tc

am

  • Nanocrystallization
  • nset is less

detectable

  • Tc (rem. am.)?

V . Franco, C.F . Conde, A. Conde, J. Magn. Magn. Mater. 203 (1999) 60

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

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SLIDE 34

Thermomagnetic properties (low T)

  • Tc(rem. am.) is

reduced with increasing Ta

– Grains should be easily decoupled

100 150 200 250 300 0.0 0.2 0.4 0.6 0.8 1.0

Ta=798K Ta=823K Ta=848K

'' (a.u.)

T (K)

0.0 0.2 0.4 0.6 0.8 1.0

' (a.u.)

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

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SLIDE 35

Hysteresis loops

700 800 900 1000 1100 5 10 2000 4000 6000 8000 10000 Dynamical treatments Isochronal treatments

Hc (A/m) Ta(K)

Stress relaxation Nanocrystallization onset 2nd crystallization stage

Averaging of anisotropy?

V . Franco et al., IEEE Trans. Mag. 38 (2002) 3069

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

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SLIDE 36

Hysteresis loops

  • Coercivity has a

maximum around room temperature

  • It is displaced to lower

temperatures as crystalline volume fraction increases

– Tc(res. Am.)

100 200 300 400 500 600 700 10 20 30 40 50

Xc 7 % 16 % 20 %

Hc (Oe) T (K)

V . Franco et al., Phys. Rev. B 66 (2002) 224418

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

slide-37
SLIDE 37

Superparamagnetic relaxation

160 320 480 640 0.0 0.2 0.4 0.6 0.8 1.0

630 K 650 K 670 K 690 K 710 K

M(T)/Ms(T) H/T (A m

  • 1 K
  • 1)

Ta px Dx (nm) <> (103 B) D (nm) 775 K undetectable undetectable 18  7 5.2  0.7 800 K 0.066 9  2 41  6 6.8  0.5 825 K 0.197 12  2 112  6 9.6  0.5 850 K 0.385 13  2 113  6 9.6  0.5

V . Franco et al., J. Appl. Phys. 90 (2001) 1558

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

slide-38
SLIDE 38

Dipolar interactions between SPM nanoparticles

  • 1000
  • 500

500 1000

  • 1.0
  • 0.5

0.0 0.5 1.0

H (Oe) M/Ms

  • 1000
  • 500

500 1000

  • 1.0
  • 0.5

0.0 0.5 1.0

H (Oe) M/Ms

Sample with px= 20 % , measured at 400 K

V . Franco et al., Phys. Rev. B 66 (2002) 224418; Phys. Rev. B 72 (2005) 174424

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

*

kT H  

*

( ) H M N L k T T          

*

1 1

app

T T    

slide-39
SLIDE 39

Production of amorphous alloys I I : mechanical alloying

  • Powders can be

compacted to

  • btain the final

shape

  • For the same

nominal composition, properties are different from those of melt spun alloys

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

0.00 0.05 0.10 0.15 0.00 0.05 0.10 0.15

Collision point Detachment point

Y (m) X (m)

Initial ball position

  • 0.02

0.00 0.02

  • 0.02

0.00 0.02

Detachment point at the collision time Collision point Detachment point Initial ball position

Y (m) X (m)

Ipus et al, Intermetallics 16 (2008) 470

slide-40
SLIDE 40

I nfluence of the starting phases

Fe75Nb10B15 composition prepared using:

– crystalline boron (c-B alloy) – amorphous boron (a-B alloy)

(Fe75Nb10)100 composition (n-B alloy)

10 15 20 25 30 35 40

2 [degrees]

Exerimental Fitted Boron R-3m (34%) (N3)(NB9H11) (18%) Amorphous halo (48%)

intensity [a.u.]

Commercial amorphous boron Crystalline boron

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

J.J. Ipus, J.S. Blázquez, V . Franco, A. Conde, J. Appl. Phys. 113 (2013) accepted

slide-41
SLIDE 41

Global microstructure I XRD patterns

1 2 3 4 3 6 9 12 15

bcc-Nb phase fraction [%] t [h]

n-B alloy c-B alloy a-B alloy

  • Bcc Nb phase dissapears after 4 h miling
  • Amorphous phase developed only in B

containing alloys

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

slide-42
SLIDE 42

XRD results

1 10 1 2

e [%] milling time [h]

20 40 60 n-B alloy c-B alloy a-B alloy

D [nm]

0,286 0,288 0,290 0,292

a [nm]

10 20 30 40 0,0 0,2 0,4 0,6 0,8 1,0

crystalline fraction milling time [h]

c-B alloy a-B alloy

  • Faster amorphization in a-B alloy
  • Microstructural parameters of crystalline

phase almost stabilized after 4 h milling

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

slide-43
SLIDE 43

TEM sample preparation

Powder particle selected

(Focused Ion Beam)

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

Ipus et al, Phil. Mag. 89 (2009) 1415

slide-44
SLIDE 44

TEM sample preparation

Deposition of a protective Pt layer

Pt layer

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

Ipus et al, Phil. Mag. 89 (2009) 1415

slide-45
SLIDE 45

TEM sample preparation

After cutting with Ga ion beam

sample bridge

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

Ipus et al, Phil. Mag. 89 (2009) 1415

slide-46
SLIDE 46

TEM sample preparation

Sample attached to a Cu grid

Cu grid Pt deposition

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

Ipus et al, Phil. Mag. 89 (2009) 1415

slide-47
SLIDE 47

TEM sample preparation

Final thinning using Ga ion beam

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

Ipus et al, Phil. Mag. 89 (2009) 1415

slide-48
SLIDE 48

TEM sample preparation

Bright field TEM image of the sample

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

Ipus et al, Phil. Mag. 89 (2009) 1415

slide-49
SLIDE 49

Local microstructure

Amorphous matrix with boron inclusions and dispersed -Fe type nanocrystals

400 nm

10 nm-1

(0 0 2) (1 1 1)

SAD amorphous matrix CBED crystalline inclusion

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

slide-50
SLIDE 50

Microanalysis

200 300 400 500 Matrix

E [eV]

Boron particle

counts [a.u.]

Spectrum Line

  • Inclusions highly enriched in boron
  • Presence of boron in the matrix

Compositional profiles: line spectra Spot spectra

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

slide-51
SLIDE 51

Hysteresis loops

  • 10000

10000

  • 200
  • 100

100 200

M [emu/g] H [Oe]

0,5 h 4 h 6 h 20 h 40 h n-B alloy

  • 10000

10000

  • 200
  • 100

100 200

M [emu/g] H [Oe]

c-B alloy

  • 10000

10000

  • 200
  • 100

100 200

M [emu/g] H [Oe]

a-B alloy

  • 100
  • 50

50 100

  • 10

10

M [emu/g] H [Oe]

a-B alloy Victorino Franco. European School of Magnetism. Cargèse (France) 2013

slide-52
SLIDE 52

Saturation magnetization

0,0 0,2 0,4 0,6 0,8 40 80 120 160 c-B alloy (350 rpm) c-B alloy (150 rpm) a-B alloy

MS [emu/g] XC 10 20 30 40 40 80 120 160 n-B alloy c-B alloy a-B alloy

milling time [h] MS [emu/g]

10 20 30 40 80 120 160 n-B alloy c-B alloy a-B alloy

MS [emu/g] <HF> [T]

MS decreases as amorphous phase develops

Linear correlation between MS and < HF> Two slopes in MS vs Xc should indicate different rates of B incorporation into the matrix

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

slide-53
SLIDE 53

Coercivity

Coercivity initially increases and further on decreases

10 20 30 40 30 60 90 120 n-B alloy

HC [Oe] milling time [h]

a-B alloy c-B alloy

S C eff c

M H K p  

Herzer, IEEE Trans Mag 26, 1397 (1990)

0.64

c

p 

for cubic shape particles

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

slide-54
SLIDE 54

Magnetic anisotropy

10 20 30 40 30 60 90 120 n-B alloy

HC [Oe] milling time [h]

a-B alloy c-B alloy

0,0 0,4 0,8 1,2 1,6 4 8 12

pc Keff [10

3(J/m 3)]

microstrains [%]

c-B alloy a-B alloy n-B alloy

  • Initial increase due to the increase of

microstrains

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

slide-55
SLIDE 55

Magnetic anisotropy

10 20 30 40 30 60 90 120 n-B alloy

HC [Oe] milling time [h]

a-B alloy c-B alloy

0,0 0,5 1,0 1,5

10 20 30

Keff

2 [10 7(J/m 3]

XC

2 D 3 Keff 3/2 [10

  • 18(J/m)

3/2]

2 2 2 3 3 2 2 1 3 2

3 3 2 2

C eff eff S ma S mi

X D K K K A                           

Shen, Phys. Rev. B 72, 014431 (2005); Ipus Phys. Express 2, 8 (2012)

  • Reduction after 6h

due to crystal refinement

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

slide-56
SLIDE 56

LOSSES

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

slide-57
SLIDE 57

Hysteresis losses

  • Quasistatic

hysteresis loop

  • Energy dissipated in

a toroidal core over

  • ne cycle
  • Combining Ampere

and Lenz laws

  • The energy lost per

unit volume is given by the area of the loop

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

0 ( ) ( ) t T t

W i t V t dt

 

 

t T t

dB W lA H dt lA HdB dt

 

 

  

slide-58
SLIDE 58

I ncreasing frequency

  • Loops get broader and

rounder

  • Effect of eddy currents

induced in the material

  • Change in Minduced

voltage which opposes the flux change

  • Losses emerge due to

the heating of the sample due to these currents

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

D.C. Jiles, J. Appl. Phys. 76 (1994) 5849

slide-59
SLIDE 59

Classical eddy currents

  • The material is

uniformly magnetized

  • Change in

Minduced voltage which opposes the flux change

  • Losses emerge due

to the heating of the sample caused by these currents i2R

  • Powe loss per unit

volume at low frequency

  • Reduce losses by:

– Reduzing d – Increasing resistance

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

R.C. O’Handley, “Modern Magnetic Materials”, Willey, 2000

2 2 2

/

m class

B d P vol   

slide-60
SLIDE 60
  • The flux change is

restricted to the environment of the wall

  • Losses depend on the

velocity of the wall

– Drag field

  • For multiple walls,

currents interfere and reduce the losses

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

slide-61
SLIDE 61

I nfluence of induced anisotropies

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

F . Fiorillo, C. Beatrice, J Supercond Nov Magn 24 (2011) 559

slide-62
SLIDE 62

More sofisticated models

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

F . Fiorillo, C. Beatrice, J Supercond Nov Magn 24 (2011) 559

slide-63
SLIDE 63

Perspectives of core loss reduction in GOSS

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

  • T. Kubota, M. Fujikura, Y

. Ushigami J. Magn. Magn. Mater. 215-216 (2000) 69

slide-64
SLIDE 64

HI GH FREQUENCY POWER CONVERSI ON

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

slide-65
SLIDE 65
  • Designing an inductive component
  • For the same voltage amplitude, the

section is inversely proportional to the frequency

  • Go to higher frequencies in power

converters to decrease the volume and weight

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

2

cos( ) cos( )

  • dB

dI N A V NA L LI t I t dt dt l             

slide-66
SLIDE 66
  • High frequency power converters use

active switching circuits and PWM

– Superposition of many frequencies – Materials should have broadband capabilities

  • Heat dissipation in the inductors

– Scaling down the surface while keeping the dissipated heat brings thermal management problems

  • We have to add winding losses and core

losses

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

slide-67
SLIDE 67
  • Lower permeability allows larger

efficiency under some circumstances

  • For the same induction, we need

larger H (more current or more turns) for lower permeability materials

  • Depending if the added stored

energy is larger than the additional heating, it could be beneficial

A.M. Leary, P.R. Ohodnicki, M.E. McHenry, JOM 64 (2012) 772

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

slide-68
SLIDE 68

SENSORS: GI ANT MAGNETO I MPEDANCE

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

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SLIDE 69
  • 3
  • 2
  • 1

1 2 3

  • 1.0
  • 0.5

0.0 0.5 1.0

M/MS H/HK

The (very) basics of GMI

  • Skin penetration depth

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

   

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SLIDE 70

Giant magnetoimpedance

  • 8000
  • 4000

4000 8000 0.6 0.8 1.0

H (A/m) |Z| ()

Amorphous (as-cast) Amorphous (structurally-relaxed) Nanocrystalline (annealed at the onset) Nanocrystalline (annealed at the end)

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

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SLIDE 71

GMI vs Fluxgate field sensors

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

Y . Honkura, J Magn Magn Mater 249 (2002) 375

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SLIDE 72

Relationship anisotropy/ GMI

500 600 700 800 900 75 150 0.0 0.2 0.4 0.6

X/X

Ta(K)

16 at. % Si 9 at. % Si

R/R

500 600 700 800 900 50 100 150 200 250 16 at. % Si 9 at. % Si

<H

K> (A/m)

Ta (K)

Victorino Franco. European School of Magnetism. Cargèse (France) 2013

V . Franco, A. Conde, Materials Letters 49 (2001) 256

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SLIDE 73

Conclusions

  • Soft magnetic materials are used in

numerous energy-related applications

  • Coercivity can be optimized by properly

designing the microstructure of the materials

– Random anisotropy model

  • High temperature soft magnetic

amorphous alloys are a challenge

  • Amorphous and nanocrystalline alloys

can be a good testing ground to develop models of multiphase magnetic systems

Victorino Franco. European School of Magnetism. Cargèse (France) 2013