xafs studies in u7c wiggler beam-line of nsrl shiqiang wei, xinyi zhang
DESCRIPTION
XAFS Studies in U7C Wiggler Beam-line of NSRL Shiqiang Wei, Xinyi Zhang Hongwei Yang, and Faqiang Xu National Synchrotron Radiation Laboratory University of Science & Technology of China Hefei, 230029, P.R.China. NSRL in Hefei, China. The Storage Ring at NSRL. - PowerPoint PPT PresentationTRANSCRIPT
XAFS Studies in U7C Wiggler XAFS Studies in U7C Wiggler
Beam-line of NSRLBeam-line of NSRL
Shiqiang Wei, Xinyi ZhangShiqiang Wei, Xinyi ZhangHongwei Yang, and Faqiang XuHongwei Yang, and Faqiang Xu
National Synchrotron Radiation LaboratoryNational Synchrotron Radiation LaboratoryUniversity of Science & Technology of ChinaUniversity of Science & Technology of China
Hefei, 230029, P.R.ChinaHefei, 230029, P.R.China
NSRL in Hefei, China
The Storage Ring at NSRL
The beamline planned and Operated in NSRL
U4 IR and Far IR SpectroscopyU7A LIGAU7B X-ray Diffraction and ScatteringU14 Atomic and Molecular SpectroscopyU18 Soft X-ray MCDU19 Surface PhysicsU25 Photo-Acoustic and Photo-Thermal SpectroscopyU27 Metrology and Spectral Radiation Standard
In construction
In Operation
U1 X-ray lithographyU7B XAFSU10A Photo-ChemistryU10B Time-Resolved SpectroscopyU12A Soft X-ray MicroscopyU20 Photoelectron Spectroscopy
3-pole superconducting wiggler of 6T
Beam from bending magnet and superconducting wiggler
Monochromator of Si (111) double crystals
U7C XAFS station of NSRL
Side view of XAFS beamline at NSRL
159
5
43
2
Front end Differential segment Monochromatic system
1
6
7
8
10
1112
13 14
16 17
18
SuperconductingWiggler
ExperimentHutch
1. Handle valve 2. Water cooling mask 3. Pressure valve 4. Fast control valve 5. Separating diaphragm6. Beam stop 7. Pressure valve 8. Absorption Be window 9. Diaphragm 10. Pressure valve11. Entry slit 12. Flux monitor 13. Double crystal monochromator 14. Exit slit 15.Fluorescent screen16. Beam stop
Huber 420Goniometer
Huber9011Motor
Controller
HeidenhanND261Angle
Display
MikeEncoder
Oriel 18011Mike
EncoderController
Keithley6517
Electrometer
IEEE488 RS232 RS232IEEE488
Computer
Q2
Keithley6517
Electrometer
IEEE488
SR Light Sample
Q1
Printer- Plotter
Si(111)Double-CrystalMonochromater
Controlled Systems of U7C XAFS Beamline and Station
Table 1 Main performance parameters of U7C stationTest Results
Ring energyCurrentReceived Angle (H×V):
0.8 Gev160 mA1× 0.1 mrad2
Monochromator: Si(111)double crystalBeam size: 12× 1 mm2
Resolution (E/E): 3× 10-4
Energy range: 4.113.0 keVDetect system: N2/Ar mixed gas
Keithley Model 6517Electrometer
Qs1 Qs2SR
Sample
Computer
IEEE-488
Keithley 6517Electrometer
Keithley 6517Electrometer
Schematic diagram of detector system for charge measurement
Equivalent Circuit of Keithley 6517 Electrometer
XAFSPhoton energy 5–12 keVResolution 10-4@12 keVFlux 1× 1010 photons/sec
K edge Z=22 33∼L edge Z=52 73∼
Transmission Fluorescence In situ measurements
U7C of XAFS station open for users in Dec. 1999
4000 6000 8000 10000 12000 14000
109
108
Flux Intensity of U7C Beamline at the Sample PositionFlux Intensity of U7C Beamline at the Sample Position
of Hefei National Synchrotron Radiation Laboratoryof Hefei National Synchrotron Radiation Laboratory
Pho
ton
Flux
( p
h/s
)
Energy ( eV )
8500 9000 9500 100000.0
0.5
1.0
1.5
2.0
X-ray absorption spectrum of K edge for Cu foilX-ray absorption spectrum of K edge for Cu foil
Cu foil (NSRL)
x (
Arb
. Uni
ts )
Energy ( eV )
X-RAY ABSORPTION SPECTRUM OF K-EDGE FOR TiO2 POWDER
10800 11200 11600 12000 12400
Ge powder
Energy ( eV )
X-RAY ABSORPTION SPECTRA OF K-EDGE FOR Ge POWDER
Comparison for the XAFS spectra of Cu foilmeasured in BSRF, KEK and NSRL laboratory
8500 9000 9500 100000.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
Comparisons for the XAFS spectra of Cu foil measured in BSRF , K EK and NSRL laboratory
Cu foil (N SRL )
Cu foil (KE K )
Cu foil (BSRF)m
x ( A
rb. U
nits
)
Energy ( eV )
1 Annealed crystallization of 1 Annealed crystallization of Ni-B and Ni-P Ni-B and Ni-P nano-amorphous alloys nano-amorphous alloys
APPLICATIONS of U7C XAFS STATION
Significations
• TM-M type Ultrafine amorphous alloy (TM=Ni, Co, Fe; M=B, P) have the high ratio of surface atoms and amorphous structure.
• Applications in ferrofluid, catalysts and magnetic recording materials.
• X-ray-absorption fine structure study on
devitrification of ultrafine amorphous NiB alloy
Phys.Rev.B63, 224201(2001).
Shiqiang Wei, Hiroyuki Oyanagi,
Xinyi Zhang, Wenhan Liu, • Annealed crystallization of ultrafine amorphous NiB
alloy studied by XAFS Journal of Synchrotron Radiation, 8, 566(2001).
Shiqiang Wei, Zhongrui Li, Shilong Yin, Xinyi Zhang.
PreparationPreparation
Chemical method:
KBH4, 2 mol/LKBH4, 2 mol/L
Ni(CH3COO)2 Ni(CH3COO)2 4H2O, 0.25 mol/L 4H2O, 0.25 mol/L
ice-water bath and vigorously agitated by a ice-water bath and vigorously agitated by a magnetic stirrer. magnetic stirrer.
1.1 Catalytic activities of nano-amorphous Ni-B and Ni-P for Benzene Hydrogenation
100 200 300 400 500 600
230oC
380oC325oC
360oC
300oC
NiB
NiP
dH /
dT
temperature (oC)
1.2 DTA profiles of NiB and NiP
30 40 50 60 70oooooo o
oo
oooo c-Nic-Ni
3B
+
o
+ o
+ooo
ooo
oooo
(111
) 2.0
3 A
(301
) 1.6
1 A
(230
) 1.6
8 A
(122
) 1.7
2 A
(2
00) 1
.76
A
(221
) 1.8
5 A
(112
) 1.9
3 A
(0
31) 1
.97
A
(102
) 2.0
2 A
(211
) 2.1
2 A
(201
) 2.2
3 A
(121
) 2.3
5 A
(2
10) 2
.42
A
Inte
nsity
(arb
. uni
ts)
773 K
673 K
623 K573 K473 K
Ni-B (initial)
2 (degree)
1.3 XRD results of NiB with different annealed temperatures
XRD spectra of NiP at different temperature
30 40 50 60 70
0.17
6 nm
0.19
4 nm
0.
203
nm0.
214
nm
773 K
573 K
523 K
Ni-P(initial)
Inte
nsity
/ a.
u
2 / degree
-100
-50
0
50
100
150
Ni-B
Ni-B (initial)
473 K
573 K
623 K
673 K
773 K
Ni foil
1601208040
k3 (k
)
k ( nm-1 )40 60 80 100 120 140 160
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
Ni-P (initial)
573 K
473 K
673 K
773 K
Ni foil
(k)
k ( nm-1 )
1.4 XAFS results k3(k)-k function of NiB and NiP
0
500
1000
1500
2000
2500
Ni-P ( initial )473 K573 K
673 K
773 K
Ni foil
1.00.80.60.40.2FT
Am
plitu
de (
a.u.
)
Distance / nm
0
500
1000
1500
2000
2500
Ni-B ( initial )473 K573 K623 K
673 K
773 K
Ni foil
1.00.80.60.40.2
FT A
mpl
itude
( a.
u. )
Distance / nm
40 60 80 100 120 140
-40
-20
0
20
40
60
80
773 K
673 K
573 K
473 K
NiB(initial)
Ni-B3
FITTINGEXPERIMENT
K3
(K)
K(nm-1)50 100 150
0
20
40
60
80
573K
773K
Ni-P (initial)
Ni foil
k3 (k
)
k (nm-1)
Fitting results of NiB and NiP
Sample Annealing Pair Rj (nm) R0 (nm) N T (10-2 nm) S(10-2 nm) E0 (eV) Temp Ni-B 25 oC Ni-Ni 0.274 0.2410.001 11.01.0 0.69 3.3 -0.2 Ni-B 0.218 0.2150.001 2.70.2 0.46 0.34 -4.7Ni-P 25 oC Ni-Ni 0.271 0.2430.001 10.01.0 0.60 2.8 -2.9 Ni-P 0.223 0.2150.001 1.60.2 0.40 0.80 5.3Ni-B 300 oC Ni-Ni 0.255 0.2430.001 9.91.0 0.60 1.1 -0.9 Ni-B 0.218 0.2150.001 2.60.2 0.60 0.34 5.0Ni-P 300 oC Ni-Ni 0.258 0.2420.001 10.11.0 0.63 1.6 -1.3 Ni-P 0.222 0.2150.001 0.80.2 0.49 0.65 8.7Ni-B 500 oC Ni-Ni 0.249 0.2450.001 10.81.0 0.70 0.39 1.6 Ni-B 0.217 0.2150.001 0.30.2 0.56 0.23 -5.0Ni-P 500 oC Ni-Ni 0.255 0.2430.001 10.41.0 0.60 1.25 -2.8 Ni-P 0.225 0.2190.001 0.60.2 0.40 0.56 7.6Ni foil Ni-Ni 0.249 12.0 0.74 Average distance Rj=R0+σs R’s error=0.001 nm , T’s error=0.0510-2 nm , S’s error=0.110-2 nm 。
ConclusionThe XAFS results demonstrate that a fcc-like nanocrystalline Ni phase with a medium-range order is formed at 573 K where the first exothermic process is observed. The metastable intermediate states consist of the two phases, i.e., nanocrystalline Ni and crystalline Ni3B alloy.
We have noted that the S of Ni-Ni shell significantly decreases from 0.033 to 0.0029 nm, after NiB being annealed at the temperature of 773 K. The structural parameters of NiB sample is almost the same as that of Ni foil. Nevertheless, the S (0.0125 nm) of NiP sample is rather larger.
2 Structural transitions for immiscible Fe-Cu system
induced by mechanical alloying
Significations
• The method of mechanical alloying can largely increase the solid solubility of immiscible Fe100-xCux alloy. • Unique electronic and magnetic properties for Fe-Cu system. • The mechanism enhanced solubility of Fe-Cu alloy is not clear.
• Structural transitions of mechanically alloyed Fe100-xCux
system studied by X-ray absorption fine structure Physica B, 305, 135(2001) Shiqiang Wei, Wensheng Yan, Yuzhi Li, Wenhan Liu, Jiangwei Fan, and Xinyi Zhang• Metastable structures of immiscible FeXCu100-X system
induced by mechanical alloying. J.Phys. CM, 9, 11077(1997). Shiqiang Wei, Hiroyuki Oyanagi, Cuie Wen, Yuanzheng Yang, and Wenhan Liu.
Preparations• Alloy omposition Fe100-xCux
x= 0, 10, 20, 40, 60, 80, 100. • WC balls to the mixed Fe-Cu powder 10 to 1. • MA milling rate: about 210 r/min.
k3(k)-k function of Fe100-xCux
4 8 12 16
-40
0
40
80
120
160
4 8 12 16
-40
0
40
80
120
160
(b)(a)
A
o
Fe90
Cu10
Fe20Cu80
Fe30
Cu70
Fe40Cu60
Fe60cu40
Fe80
Cu20
Fe-Cu powder
Fe K-edge
k ( A-1 )
k3 (k)
A
o
Cu K-edge
Fe90Cu10
Fe80
Cu20
Fe60
Cu40
Fe40
Cu60
Fe30Cu70
Fe20
Cu80
Fe-Cu powder
k3 (k)
k ( A-1)
RDFs of Fe100-xCux alloys
0 2 4 6
500
1000
1500
2000
2500
3000
3500
0 2 4 6
500
1000
1500
2000
2500
3000
3500
o
Cu K-edge
Fe90
Cu10
Fe80
Cu20
Fe60
Cu40
Fe40
Cu60
Fe30
Cu70
Fe20
Cu80
Cu-Fe powderF(
r)
Distance( A )(a) (b)
o
Fe90
Cu10
F(r)
Distance( A )
Fe20
Cu80
Fe30
Cu70
Fe40
Cu60
Fe60
cu40
Fe80
Cu20
Fe-Cu powder
Fe K-edge
Fitting results of the Fe100-xCux samples
4 6 8 10 12 14-80
-40
0
40
80
120
160
4 6 8 10 12 14-80
-40
0
40
80
120
160
(a)
ok( A-1 )
Fe-Cu powder
Fe40
Cu60
Fe30
Cu70
Fe20
Cu80
Fe60
Cu40
Fe80
Cu20
Fe90
Cu10
Fe K-edge
k3 (k)
(b)
ok( A-1)
Fe-Cu powder
Fe20
Cu80
Fe30
Cu70
Fe40
Cu60
Fe60
Cu40
Fe80
Cu20
Fe90
Cu10
Cu K-edge
k3 (k)
The structure parameters of Fe100-xCux by fitting the Fe K-edge EXAFS spectra
Sample Bond type R(Å) (Å) N E0
Fe powder Fe-Fe 2.480.02 0.0700.005 8.00.5 2.97
Fe90Cu10 Fe-Fe 2.480.02 0.0780.005 7.60.5 -4.01
Fe-Cu 2.480.02 0.0800.005 0.70.3 -1.59
Fe80Cu20 Fe-Fe 2.480.02 0.0810.005 7.20.5 -2.01
Fe-Cu 2.480.02 0.0810.005 1.20.3 4.31
Fe60Cu40 Fe-Fe 2.570.02 0.0990.005 8.70.5 0.64
Fe-Cu 2.560.02 0.0990.005 3.50.3 -4.99
Fe40Cu60 Fe-Fe 2.580.02 0.0990.005 6.90.5 4.99
Fe-Cu 2.580.02 0.0990.005 5.60.5 2.63
Fe30Cu70 Fe-Fe 2.580.02 0.0980.005 5.70.5 4.96
Fe-Cu 2.580.02 0.0980.005 6.40.5 2.94
Fe20Cu80 Fe-Fe 2.580.02 0.0980.005 5.00.5 4.95
Fe-Cu 2.580.02 0.0980.005 7.10.5 3.45
The structure parameters of Fe100-xCux by fitting the Cu K-edge EXAFS spectra
Sample Bond type R(Å) (Å) N E0
Fe90Cu10 Cu-Cu 2.480.02 0.0780.005 1.50.3 -3.1
Cu-Fe 2.480.02 0.0730.005 6.70.5 -5.0
Fe80Cu20 Cu-Cu 2.500.02 0.0820.005 2.10.3 4.8
Cu-Fe 2.490.02 0.0810.005 6.20.5 4.0
Fe60Cu40 Cu-Cu 2.550.02 0.0890.005 7.10.5 2.7
Cu-Fe 2.550.02 0.0870.005 4.60.5 0.9
Fe40Cu60 Cu-Cu 2.560.02 0.0890.005 8.40.5 -3.9
Cu-Fe 2.540.02 0.0890.005 3.30.3 -4.3
Fe30Cu70 Cu-Cu 2.550.02 0.0890.005 9.70.5 -1.8
Cu-Fe 2.540.02 0.0890.005 2.30.3 -3.8
Fe20Cu80 Cu-Cu 2.550.02 0.0890.005 9.80.5 -2.1
Cu-Fe 2.540.02 0.0880.005 1.50.3 -4.6
Cu powder Cu-Cu 2.550.02 0.0890.005 12.00.5 0.4
Conclusions
The local structures around Fe and Cu atoms depend on the initial composition. Fe100-xCux solid solutions x40, fcc-like structure x20, bcc-like structure
• The fitting results indicate that the MA FexCu
100-x alloys with x40 are inhomogeneous supersaturated solid solutions, and there are a fcc Fe-rich and a fcc Cu-rich regions in solid solutions. For lower Cu concentrations with x20. The evolution of the FT intensities and structural parameters of Fe atoms is identical with those of Cu atoms. This result suggests that the Cu atoms be almost homogeneously incorporated into the bcc Fe-Cu phase.
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