Design of magnetic bearings for turbo refrigerant compressors
Search for magnetic refrigerant materials
28
- Lian Zhang Search for magnetic refrigerant materials WZI group meeting May 28 WZI group meeting May 28 th th 2003, UvA 2003, UvA
description
Search for magnetic refrigerant materials. - Lian Zhang. WZI group meeting May 28 th 2003, UvA. Outline. What & why is MR? Search for candidate materials Gd 5 (Si,Ge) 4 Fe 2 Mn(Si,Ge) La(Fe,Si) 13 MnFe(P,As) Conclusion. Fleet. FR de Boer, KHJ Buschow - PowerPoint PPT Presentation
Transcript of Search for magnetic refrigerant materials
- Lian Zhang
Search for magnetic refrigerant materials
WZI group meeting May 28WZI group meeting May 28thth 2003, UvA 2003, UvA
Outline
What & why is MR? Search for candidate materials
Gd5(Si,Ge)4
Fe2Mn(Si,Ge)
La(Fe,Si)13
MnFe(P,As) Conclusion
Fleet
FR de Boer, KHJ Buschow
E Brück, A de Visser, J Klaasse, YK Huang
O Tegus
AL Wolf
Why magnetic refrigeration? Conventional gas expansion cooling
Ozone depletion Global warming
Green MR Higher efficiency Less noisy More compact Low temperature capability
Magnetic Refrigeration• Magnetic-materials change in temperature if subjected to
magnetic-field change Magnetocaloric effect
)()(),(),( TSTSTBSTBS ellatmag
S
T
B0
B=0
Ericsson
Q
Q
Carnot
T1T2
S2
S1
Sm
Tad
Refrigerant capacity
Table-like
S
T
Integration from isothermal magnetization curves
Directly measure or compute from specific heat measurements
T
SB
M B1 > B2
T1
T2
T3
T4
:
:
Tn
Composite materialTC
Field-induced or not, Field-induced or not, behaves differently. behaves differently.
GdGd55(Si,Ge)(Si,Ge)44
Magnetostructural Magnetostructural transitiontransition
MM
TT
Hysteresis
Misleading messageMisleading message
M. Nazih Solid State Comunications 126 (2003)
210 220 230 240 250 260 270 280 290 300 310
0
10
20
30
40
50
Gd5Si
1.7Ge
2.3 Sigle Crystal //a
1T 2T 3T 4T 5T
T (K)
-S
(J/
kgK
)
O. Tegus Physica B 319 (2002)
Fe2Mn(Si1-xGex)
Fe3Si: TC > 800 K
Fe2MnSi: TC ~ 250 K
Cubic D03
Heusler-type
Fe3Ge: D019 (HT)
L12 (LT)
20 30 40 50 60 70 80
Inte
nsity
(ar
b. u
nit)
10 h
4 h
2 h
1 h
0.5 h GeFeGeMn
Ge
Fe (100)
Mn
Ge (111)
2 (Deg)
L. Zhang J. Alloys Comp. 352 (2003)
D03 D019
0.0 0.2 0.4 0.6 0.8 1.00
100
200
300
400
500
D019
D03
Para
T (
K)
x
0.0 0.2 0.4 0.6 0.8 1.0
5.66
5.68
5.70
5.72
5.74
5.76
5.78
a
(Å
)
X (Ge content)
Lattice change with Ge content
TC - Ge content
20 30 40 50 60 70 80 90 100
D019
D019
+D03
D03
Fe2MnSi
1-xGe
x
x=1
x=0.8
x=0.6
x=0.5
x=0.4
x=0.2
x=0
In
ten
sit
y (
arb
. u
nit
)
2 (Deg)
30 40 50 60 70 80 90 100
440
422
400
220
00440
1222
203
220
202
201
002
200
Difference
Calculated
Observed
Inte
nsity
(ar
b. u
nit)
2 (Deg)
L. Zhang Physica B 328 (2003)
0 50 100 150 200 250 300 350 4000.0
0.2
0.4
0.6
0.8
1.0
1.2
a
M
( B
/f.u
.)
T (K)
0 50 100 150 200 250 300 350 4000.0
0.5
1.0
1.5
2.0
2.5
3.0
b
M ( B
/f.u
.)
T (K)
220 240 260 280 3000.0
0.5
1.0
1.5
B=2T
B=5T
-S
(J/
kg·K
)
T (K)
Disappointed!
La(Fe,Si)13
The highest 3d metal concentration (1:13) in RT intermetallic compounds
Failed to be a good permanent magnet
Cubic: weak anisotropy
Palstra 1983
FeI @8b
FeII @96i
La @8a
Hypothetical LaFe13 structure:
Space group = Fm-3c
Unit cell = 8 f.u. = 112 atoms
= 8 La + 8 FeI + 96 FeII
Al, Si
Moze 1999
Modification
Substitution of Fe by other transition metalsMn: failed to get single phase LaFe10.92Mn0.65Si1.43 Co: LaFe10.92Co0.65Si1.43 has a 2nd transition at TC=265K
Doping with interstitial atomsB: -Fe emerges in small amount of doping (B=0.2)N: difficulty in diffusion makes sample inhomogeneous
and broadens the transition enormously
C: saturated at C=0.5, while TC=250K
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.00.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
B/F
e
B (T)
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.00.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
B/F
e
B (T)
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.00.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
B/F
e
B (T)
Field step 0.1T
Field step 0.02T
Field step 0.005T
Be cautious with the height of S peak when it is a 1st order field-induced transition.
186 188 190 192 194 196
-40
-20
0
20
40
60
-
S
T (K)
For the field-induced 1st order transition, the field-up S-T show point rotation symmetry with the field-down S-T curve.
MnFe(P,As)
MnFePMnFeP MnFeAsMnFeAs
TT(K)(K)
400
300
200
100OrthOrth
AFAF
TTNN
TTNN
AFAF
TTCC
FF
TetrTetrHexHex
TTNN
ss
((BB/f.u.)/f.u.)ss
4
3
2
1
AFAF
Beckman-Lundgren, 1991Beckman-Lundgren, 1991
O. Tegus Physica B 319 (2002)
Virgin effectVirgin effect
44 46 48 50 52 54 56
In
tens
ity
2deg.)
c
b
a
a
b
c
X=0.4X=0.4 X=0.2X=0.2
X=0.2
X=0.2
X=0.4
Conclusion
Materials for MR are ready Much room for improvement Behaviors vary: rich ingredients Theories are called Accommodate engineering challenges
