Transcript Phase Separation in Magnetic Oxides: Mesoscopic vs

Advanced neutron spectrometers for condensed
matter studies at the IBR-2M reactor
Anatoly M. Balagurov
Frank Laboratory of Neutron Physics,
JINR, Dubna, Russia

Neutron scattering for condensed matter
science.

IBR-2M pulsed reactor as a neutron source
of third generation.

Performance of neutron scattering
spectrometers at the IBR-2M.

Perspectives.
Hydrogen: primary energy sources,
energy converters and applications
1
Neutron space and time domain
S(Q, ω) ~ ∫∫ei(Qr – ωt) G(r, t)drdt
l ~ 2π/Q, τ ~ 2π/ω
For elastic scattering:
ΔQ = (10-3 – 50) Å-1
Δl = (0.1 – 6·103) Å
Nanostructured materials are inside!
Neutron scattering features:
- Strong magnetic interaction,
- Sensitivity to light atoms,
- Sensitivity to isotopes,
- Large penetration length, …
2
Success of neutron scattering experiment depends on:
I. Parameters of a neutron source
average power, pulse width, spectral distribution, ...
II. Performance of a spectrometer
intensity, resolution, (Q, E)-range, available sample environment, ...
III. Team at spectrometer
head of team, experience, contacts, ...
3
Neutron sources for condensed matter studies
I. Continuous neutron sources
II. Pulsed neutron sources
W = 10 – 100 MW
Const in time
VVR-M, Russia
IR-8, Russia,
ILL, France
LLB, France
BENSC, Germany
FRM II, Germany
BNC, Hungary
NIST, USA
ORNL, USA
…
SINQ, Switzerland
II-a. SPS
W = 0.01 – 1 MW
Pulsed in time
Δt0 ≈ (15 – 100) μs
ISIS, UK
LANSCE, USA
SNS, USA
KENS, Japan
J-SNS, Japan
II-b. LPS
W = 2 – 5 MW
Pulsed in time
Δt0 ≈ (300 – 1000) μs
IBR-2M, Russia
ESS, Europe
LANSCE (new)
???
4
TOF high-resolution diffractometer at LPS type source
Neutron pulse after fast
chopper Δt0 ≈ (20 – 50) μs
Fermi chopper
with 2 slit
packages
21.79 m
22.5 m
23.5 m
29.9 m
6 Disc
choppers
49.6 m
73.4 m
Δd/d ≈ 0.001 for back scattering
Magnet (25 T)
5
HRFD – High Resolution Fourier Diffractometer at IBR-2
Y123
High resolution
0.1%
Put into operation in 1994 in collaboration
between: FLNP (Dubna), PNPI (Gatchina),
VTT (Espoo),
IzfP (Drezden)
Y123
Medium resolution
1%
0.7
1.0
1.3
1.6
d, Å
1.9
2.2
2.5
6
hrf-hrp1
Al2O3
HRPD, DRAL
L=100 m
HRFD resolution
The utmost TOF
resolution of HRFD
500 rpm
Al2O3
HRFD, FLNP
L=20 m
TOF width, microsec.
Ge-powder
100
Experimental:
y(x)=0.87 + 59.54x
1000 rpm
50
2000 rpm
4000 rpm
6000 rpm
0
0.0
1.22 1.24 1.26 1.28 1.30 1.32 1.34 1.36 1.38
d, Å
Diffraction patterns of Al2O3 measured at
ISIS (UK) and IBR-2 (Dubna). Resolution is
the same, despite L is 5 times longer at ISIS.
Theoretical:
y(x)=0 + 58.50x
0.5
1.0
1.5
1/Velocity (1000/rpm)
velo-Ge
2.0
For V=11,000 rpm & L=30 m
Rt=0.0002 (0.0009 now)
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Neutron spectrometers on the IBR-2M reactor
Diffraction (6):
HRFD, DN-2, SKAT, EPSILON,
FSD, DN-6
SANS (2):
YuMO, SANS-C
Reflectometry (3):
REMUR, REFLEX, GRAINS
Inelastic scattering (2):
NERA, DIN
13 spectrometers (3 new)
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Spectrometers on existing pulsed neutron sources*
Technique \
Source
IBR-2(M)
(Russia)
ISIS**
(UK)
IPNS*** LANSCE
(USA)
(USA)
KENS
(Japan)
Diffraction
6 (6)
8 (+2)
4
6
5
SANS
1 (2)
2 (+1)
2
1
1
Reflectometry
2 (3)
2 (+3)
2
2
2
Inelastic Scat.
3 (2)
9 (+1)
3
3
5
Total
12 (13)
21 (+7)
11
12
13
* At a new SNS (Oak Ridge) neutron source 18 spectrometers are planning
** Numbers in brackets – spectrometers at the II Target Station
*** IPNS is closed in the very beginning of January 2008
9
Diffraction at the IBR-2M
1. HRFD*
powders – atomic and magnetic structure
2. FSD*
bulk samples – internal stresses
3. DN-2
powders – real-time, in situ
4. DN-6
microsamples – high-pressure (new project)
5. EPSILON** rocks – internal stresses
6. SKAT** rocks – textures
* Fourier RTOF technique
** Long (~100 m) flight pass
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Diffraction at the IBR-2M. Resolution.
0.1
TOF_Resolut_Com
Resolution, d/d
DN-2/DN-6
0.01
SKAT/EPSILON
FSD
HRFD powders
FSD
internal stresses
DN-2
real-time, multilayers
DN-6
high-pressure
EPSILON stresses
SCAT
textures
HRFD
0.001
Resolution becomes better
for longer d-spacing!
0.0001
0
1
2
3
4
5
6
7
8
d, Å
11
1
2
No 1
1.
2.
No4
4
3.
20K
4.
No 5
300K
Chamber of the
cold moderator.
Light water premoderator.
Flat water
reflector.
Outer border of
the reactor jacket.
No 6
water
3
No 9
Combi-moderator at the central direction of
the IBR-2M reactor, plan view
12
Cold moderators at the IBR-2M reactor
v99-45r
y99-hc
20
YbFeO 3
a=5.56 Å
b=7.56 Å
c=5.23 Å
R= I(30 K) / I(300 K)
10
Ratio
8
6
4
HRFD, D1
Tmod=30 K
Diffraction on SPB
2
1
2
3
4
5
6
Intensity
Scattering on V
1
7
Wavelength (Å)
Gain factor as a function of λ
v99-1w
300 K
HRFD, D1
Tmod=300 K
Intensity
30 K
60 K
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
d (Å)
0
2
4
6
8
10
Wavelength (Å)
Diffraction patterns of TbFeO3
measured at Tmod=30 K and 300 K
Neutron flux distributions as a function of λ
13
HRFD development
Actual state
Resolution: one of the best in the world
Intensity: not high enough (Ωd≈0.2 sr)
Could be
Resolution: best among neutron diffractometers
Intensity: 10 times better than now
1. Neutron guide
2. Detector array
3. Correlation electronics
~500 KUSD
14
New diffractometer for micro-samples and
high-pressure studies
Chopper
Actual state
Neutron guide
Sample
Ring-shape detectors
Resolution: optimal for high-pressure studies
Intensity: one of the best in the world
Pressure: up to 7 GPa in sapphire anvils
Ring-shape multi-element
ZnS(Ag)/6LiF detector
1. Detector array
Could be
Intensity: 25 times better than now
Pressure: 20-30 GPa in natural diamond or mussonite
2. Neutron guide
~250 KUSD
15
GRAINS: complete reflectometry at the IBR-2M reactor
FLNP: M. Avdeev, V. Lauter-Pasyuk
V. Aksenov, V. Bodnarchuk
Germany: H. Lauter
PNPI: V. Trounov, V. Ul’yanov
Parameters:
Resolution: optimal, δλ/λ = (0.3 – 7)%, angular = (1 – 10)%
Q-range: optimal, (0.002 – 0.3) Å–1
Intensity: one of the best in the world
Modes:
• Reflectometry in vertical plane,
• Off-specular scattering,
• GISANS with polarized neutrons.
Cost estimate = 1050 kEUR
Contributions:
- Germany, Hungary,
- Romania, external.
16
A new reflectometer GRAINS at the IBR-2M reactor
Main feature: vertical scattering plane → studies of liquid media
17
Frank Laboratory of Neutron Physics
Condensed Matter Department
Proposals
for IBR-2M spectrometer complex
development program
Editors: Victor L. Aksenov, Anatoly M. Balagurov
Dubna, 2006
The second edition of the proposals is under preparation.
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Proposals for 2008 – 2011
Development of existing
spectrometers
1.
2.
3.
4.
5.
6.
7.
8.
9.
HRFD (SA)
FSD (SA)
DN-2
SKAT (BMBF)
EPSILON (BMBF)
YuMO
REMUR
DIN (RosAtom)
NERA (Poland)
4,000 K$
New
spectrometers
1.
2.
3.
4.
5.
6.
DN-6
RTS
SANS-C
GRAINS
SESANS
SANS-P
General-purpose
projects
1.
2.
3.
4.
5.
Moderators
Detectors
Sample environment
Cryogenics
Electronics
2,700 K$
3,000 K$
In total: 9.7 M$ for 4 years
19
Priorities for 2008
Priorities for 2009 - 2011
Approved projects
Strategical necessity
FSD
DN-6
YuMO / SANS-C
Projects with external support
SCAT
EPSILON
GRAINS
HRFD
Projects without clear perspective
REMUR, NERA,
DIN, SESANS,
SANS-P, DN-2, RTS
20
New science after 2010
1. Modern material science
- nanostructures (catalysts, multilayers, porous materials, …),
- materials for energy (electrochemistry, hydrogen, …),
- biomaterials, polymers (soft-matter),
- new constructive materials for atomic energy,
- geological problems (earthquakes, waste deposit, …), …
2. Modern fundamental physics
- complex magnetic oxides with strong correlations,
- low-dimensional magnetism,
- phase coexistence in crystals, …
21
User program at the IBR-2 spectrometers
International experts’
Time-sharing (13 spectrometers)
commissions:
I. Diffraction
FLNP (35%)
External
fast (10%)
II. Inelastic Scattering
External
regular (55%)
III. Polarized neutrons
IV. SANS
User statistics
IBR-2 operational time:
~2000 hours/year
Number of experiments:
~150 per year
External users:
~100 per year
Others, 19%
FLNP, 25%
France, 3%
Poland,
5%
Germany,
17%
Russia, 31%
22
Condensed Matter Department at FLNP
JINR staff
Member States staff
38
28
Professor
Doctor of science
Candidate of science
Ph.D. + students
1999: 52 + 28 = 80
4
10
26
11
2007: 38 + 28 = 66
What staff do we need?
CMD administration
Heads of directions
Group at spectrometer
Technical group
Additional techniques
Scientific groups
~4
4
~ 3x13 = 39
5
~5
~ 10
~ 67
20
18
16
14
12
10
8
6
4
Age distribution
14
10
9
8
10
9
7
4
6
3
2
0
20-24 25-29 30-34 35-39 40-44 45-49 50-54 55-59 60-64 65-70
There exists a substantial deficiency of permanent staff personnel
23

IBR-2 is one of the best neutron sources in the world and the only
existing advanced neutron source among JINR Member States.

Existing spectrometers are comparable with that at other advanced
pulsed neutron sources; some of them are unique.

Experimental potential of the complex is much higher than that
existing now.

All spectrometers are accessible for international community in a
frame of accepted proposals.

Period 2008 – 2010 is most convenient for global development of
neutron spectrometers.

Adequate financial support is urgently needed.
24
Ambitious goal for Condensed Mater Department,
Frank Laboratory of Neutron Physics,
and
Joint Institute for Nuclear Research:
Experimental complex based on the IBR-2M
reactor for fundamental and applied
investigations of advanced and nanostructured
materials.
25
From White-Egelstaff law-book for
thermal neutron scattering (~1970):
Law 2:
Neutrons are to be avoided where there is an
alternative!
New version:
Neutrons can be applied everywhere, even if an
alternative there exists!
For studies of nanostructured materials as well !
26
Thank you !
27
Neutron spectrometers on the ISIS spallation source
(RAL, UK)
Diffraction (8):
GEM, HRPD, PEARL, POLARIS,
ROTAX, SXD, ENGIN-X, INES
SANS (2):
SANDALS, LOQ
Reflectometry (2):
CRISP, SURF
Inelastic scattering (9):
HET, MAPS, MARI, MERLIN,
PRISMA, IRIS, OSIRIS, TOSCA,
VESUVIO
21 spectrometers
28
from MEETING REPORT
“Consultancy on the Status of Pulse Reactors and
Critical Assemblies”
IAEA, 16 – 18 January 2008
The IBR-2 reactor at Joint Institute on Nuclear Research, Dubna is a
unique facility internationally, and is being refurbished/modernized to
continue to serve as an international centre of excellence for neutron
sciences.
29
Diffraction at the IBR-2M. Intensity.
Mo powder measured in
1 min (1) and 0.2 sec (2).
40
Intensity / Counting rate
Intensity per 0.2 sec
(2)
I ≈ Φ0 · S · Ω/4π · δ [n/s] ≥ 106 n/s
30
20
10
0
10000
(1)
Intensity per 1 min
Φ0 – neutron flux at a sample, 107 n/cm2/s
S – sample area,
5 cm2
Ω – detector solid angle,
0.2 sr
δ – scattering probability,
0.1
mol-e
(211)
8000
(110)
6000
(200)
4000
2000
0
70
90
110
130
150
Channel number
170
190
30
IBR-2M pulsed reactor (with cold moderators)
is the source of third generation*)
Source
Parameter
SNS,
USA
(SPS)
JSNS,
Japan
(SPS)
IBR-2M,
JINR
(LPS)
ESS,
Europe
(LPS)
Status
2008
2009
2010
2015 ?
Power,
kW
1200
1000
2000
5000
15 - 100
15 – 100
350
1000 ?
60
25
5
>20
Pulse width,
μs
Frequency,
s-1
*) For 2nd generation sources W is between 6 – 200 kW (IPNS, KENS, LANSCE, ISIS)
31
Resources which are needed to complete
the 2007 - 2010 program
Technical needs:
1. Neutron guides –
2. 1D PSD –
3. 2D PSD –
4. Large aperture det-s –
5. Choppers –
Financial needs (in KUSD):
~ 300 m
5
4
6
6
A. Development (9) – 4,105 (456)
B. New projects (6) – 2,991 (499)
Total (15):
7,096
6. Neutron optics devices
7. Spin analyzers & polarizers
8. Electronics & computing
9. Sample environment:
refrigerators,
thermostats,
magnets,
acoustic technique…
32
Hydrogen materials: what can we learn with neutrons?
Location of H, OH, H2O in crystal:
Dynamics of H, OH in crystal:
Diffusion of H, H2O in solids or liquids:
Clustering of H, nanostructures:
Exchange membrane, hydration/dehydration:
Quantitative analysis:
coherent elastic, diffraction.
incoherent inelastic.
quasielastic incoherent.
coherent elastic, SANS.
diffraction, reflectometry.
incoherent scattering / absorption.
H (and Li) are the most important
Elements for fuel cells and batteries!
Proton exchange membrane
33
Phase transformations of high pressure heavy ice VIII.
Time-resolved experiment with t = (1 – 5) min.
Ih
Ice VIII
Ic
hda
Time / temperature scale: Tstart=94 K, Tend=275 K. The heating rate is ≈1 deg/min.
Diffraction patterns have been measured each 5 min. Phase VIII is transformed into high
density amorphous phase hda, then into cubic phase Ic, and then into hexagonal ice Ih.
34
Project EPSILON/SKAT:
Investigation of strain/stress and texture
on geological samples
Spokesman from JINR:
Dr. Ch. Scheffzük
Spokesman from Germany:
Dr. habil. A. Frischbutter
EPSILON-MDS
SKAT
New neutron guide
Could be
Intensity: 10 times better than now
~106 EUR
35
Diffraction at the IBR-2M. General conclusion.
Unique complex with world top opportunities in:
- extremely high-resolution (HRFD),
- extremely high-intensity (DN-6, DN-2),
- applied studies (FSD, EPSILON, SKAT).
36
Polarized neutron scattering at the IBR-2M
1. REMUR magnetic multilayers – magnetic structures
2. GRAINS interface science in physics, biology, chemistry
(new project)
3. REFLEX reflectometry in horizontal plane,
now is used in test mode
37
Resolution at pulse neutron source. Elastic scattering.
R = [(Δt0/t)2 + (Δ/tg)2]1/2
For Δt0 ≈ 350 μs, L ≈ 25 m, λ ≈ 4 Å TOF contribution is ~1%.
Geometrical contribution is:
~(0.05 – 0.2)% for back scattering
~(5 – 10)% for SANS and reflectometry
TOF component in resolution function is not important for:
SANS and Reflectometry
It is not very important for:
single crystal diffraction, magnetic diffraction…
Powder diffraction: structural studies, stress analysis, low symmetry textures?
38
Criteria which could be used for the evaluation
1. Modern and interesting science.
2. Correspondence to the IBR-2M features.
3. Top level parameters.
4. Active and effective team.
5. External support (financial, technical, …).
39
Proposals at the IBR-2 reactor, JINR, Dubna
IBR-2 operational time:
~2000 hours/year
Number of experiments:
~150 per year
External users:
~100 per year
40
Research reactors in the JINR Member States
Russia
Czechia
I. Dubna, IBR-2 (1984, 2 MW, pulsed)
I. Řeź, LVR-15 (1970, 10 MW)
II. “RCC KI” Moscow, IR-8 (1957, 8 MW)
Germany
III. Gatchina, VVR-M (1959, 16 MW)
I. Munich, FRM-II (2005, 20 MW)
IV. Yekaterinburg, IVV-2M (1966, 15 MW)
II. Berlin, BENSC (1973, 10 MW)
V. Obninsk, VVR-M (1960, 12 MW)
Hungary
I. Budapest, BNC (1970, 10 MW)
The enhanced flux and new instrument concepts will allow to
improve the resolution in both space and time ==> “new science”!
41
Neutron Techniques (developed at the IBR-2)
DINS
INS
LND
NBS
ND
NHol
NI
NPol
NRad
NRef
NTom
NSE
PolN
PST
QENS
SANS
TAS
TOF
USANS
ZFNSE
Deep Inelastic Neutron Scattering
Inelastic Neutron Scattering
Laue Neutron Diffraction
Neutron Back-Scattering
Neutron Diffraction
Neutron Holography
Neutron Interferometry
Neutron Polarimetry
Neutron Radiography
Neutron Reflectometry
Neutron Tomography
Neutron Spin-Echo
Polarized Neutrons
Phase-Space Transformation
Quasi-Elastic Neutron Scattering
Small Angle Neutron Scattering
Triple-Axis Spectrometry
Time-Of-Flight (techniques)
Ultra SANS
Zero-Field NSE
At the IBR-2 the
techniques are developed,
which are the most
effective for condensed
matter studies and above
all for studies of nanostructured materials.
42