Transcript Phase Separation in Magnetic Oxides: Mesoscopic vs

Neutron scattering in condensed matter research.
20 years of regular studies at the IBR-2 pulsed reactor.
Anatoly M. Balagurov
Condensed Matter Department of Frank Laboratory of Neutron Physics, JINR
power
IBR-2
IBR-1 (1 – 6 kW)
1969 – 1980
IBR-30 (15 kW)
1981 – 1983
IBR-2 (100 – 1000 kW)
1000
Power, kW
1961 – 1968
100
IBR-30
10
1984 – 2004
IBR-2 (1500 – 2000 kW)
IBR-1
1
1960
1970
1980
1990
2000
2010
Years
tit
1
Diffraction TOF patterns: in the past and at present.
asi043
Normalized Intensity
Si
HRFD
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
d, Å
Si diffraction pattern, measured
at the IBR-1. 1965.
1st-sp
Si diffraction pattern, measured
at the IBR-2. 1994.
2
Time-of-Flight (TOF) technique at pulsed neutron source
Alternatives:
Steady state source (reactor)
W = 10 – 100 MW, const in time.
Pulsed source (reactor / accelerator) W = 10 – 2000 kW, pulses in time.
These two types are generally considered to be complimentary!
Flight path
Source pulse
High energy
Time
Neutrons are separated in energy after
traveling over a fixed path (L), permitting
neutrons of many different energies and
wavelengths to be used for experiments.
Low energy
At pulsed neutron source TOF technique is used in a natural way!
Tem
3
IBR-2 pulsed reactor (1984 – present)
Active
core
Movable
reflector
The IBR-2 parameters
Fuel
Active core volume
Cooling
PuO2
22 l
liquid Na
Average power
Pulsed power
Repetition rate
Average flux
2 МW
1500 MW
5 s-1
8·1012 n/cm2/s
Pulsed flux
5·1015 n/сm2/s
Pulse width (fast / therm.) 215 / 320 μs
Number of channels
14
IBR-2
4
The IBR-2 pulsed reactor for condensed matter research.
Comparison with other pulsed sources.
Source
Parameter
IBR-30
JINR
IBR-2
JINR
ISIS
RAL, UK
SNS
ORNL, USA
Status
1969-80
1984
1986
2006
Power,
kW
15
2000
160
1200
Pulse width,
μs
120
320
20
20
Frequency,
s-1
5
5
50
60
Diffr.-IBR2
5
The IBR-2 pulsed reactor for condensed matter research.
Comparison with other pulsed sources.
Intensity / Counting rate
I ≈ Φ0 · S · Ω/4π [n/s]
≥ 106 n/s
Φ0 – neutron flux at a sample, 107 n/cm2/s
S – sample area,
5 cm2
Ω – detector solid angle,
0.2 sr
Diffr.-IBR2
DN-2, IBR-2:
GEM, ISIS:
Ω ≈ 0.2 sr
Ω ≈ 6.0 sr
6
The IBR-2 pulsed reactor for condensed matter research.
Comparison with other pulsed sources.
Resolution
IBR-2: Δt0 ≈ 320 μs. R ≈ 0.01, DN-2.
ISIS: Δt0 ≈ 20 μs.
R ≈ 0.003, GEM.
R = [(Δt0/t)2 + (Δ/tg)2]1/2
Δt0 – pulse width,
Δ - geometrical uncertainties,
t ~ L · λ – total flight time,
 – Bragg angle.
TOF component in resolution function is not very important for:
SANS, reflectometry, single crystal diffraction, magnetic diffraction…
For high resolution experiment we use the Fourier technique !
Diffr.-IBR2
7
High Resolution Fourier Diffractometer
0.7 mm
Stator
Rotor
Fourier chopper:
N=1024
Vmax=9000 rpm
Ω = 150,000 s-1
Sbeam=3x30 cm2

Transmission
function

R(t) ≈ g(ω)cos(ωt)dω,
0
Binary signals
chopper
Δt0≈ 1/Ω = (Nωm)-1 ≈ 7 μs
8
HRFD – High Resolution Fourier Diffractometer
at the IBR-2 pulsed reactor
IBR-2
Fourier
chopper
In collaboration between:
HRFD
FLNP (Dubna), PNPI (Gatchina),
VTT (Espoo), IzfP (Drezden)
9
Diffraction patterns measured with high and low
resolution
tof-rtof
cufe-hl
Y123-Cu/Fe
High resolution
0.1%
HRFD
d/d0.001
Y123-Cu/Fe
Low resolution
1%
DN-2
d/d0.01
IBR-2, DN-2
300 s
R=0.01
IBR-2, HRFD
10 s
R=0.0007
-300
high-low
-200
-100
0
t, s
100
200
300
0.7
1.0
1.3
1.6
1.9
2.2
2.5
d, Å
10
Al2O3 standard measured
at ISIS and IBR-2
The utmost TOF
resolution of HRFD
hrf-hrp1
Al2O3
HRPD, DRAL
L=100 m
TOF width, microsec.
Al2O3
HRFD, FLNP
L=20 m
500 rpm
Ge-powder
100
Experimental:
y(x)=0.87 + 59.54x
1000 rpm
Theoretical:
y(x)=0 + 58.50x
50
2000 rpm
4000 rpm
6000 rpm
0
0.0
0.5
1.0
1.5
1/Velocity (1000/rpm)
velo-Ge
2.0
For V=11,000 rpm & L=30 m
1.22 1.24 1.26 1.28 1.30 1.32 1.34 1.36 1.38
Rt=0.0002 (d=2 Å)
d, Å
HRPD-HRFD
11
Diffraction TOF experiments with sapphire anvil highpressure cells (collaboration with “Kurchatov Institute”)
Diffractometer DN-12 at the IBR-2
Intensity
2000
(110)
(103)
DyD
b
3
P=9.5 GPa
3
V=0.027 mm
(102)
t=24 h
DN-12
1000
b
Sapphire anvil high-pressure
cell, Р up to 7 GPa (cylinder
48 mm  x 164 mm height).
1st-sp
b
0
0.8
1.0
1.2
1.4
(101)
1.6
1.8
2.0
d, Å
12
2D cross-section of (400) spot of KD2PO4 single crystal
measured by 1D PSD at T=80 K.
Simultaneous sweep
along TOF and 2 axes.
About 4000 points have
been measured in parallel.
А.M. Balagurov, I.D. Dutt, B.N. Savenko and L.A. Shuvalov, 1980.
Mono-DKDP
13
Phase transformations of high pressure heavy ice VIII.
Time-resolved experiment with t=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.
real-time
14
Magnetic off-specular neutron scattering from (001)
[Cr(12Å)/57Fe(68Å)]x12 /Al2O3 multilayer
Intensity map of specular and offspecular scattered neutrons from
the Fe/Cr multilayer (SPN data).
Neutron wavelength, Å
Result of the supermatrix
calculations with the model
of non-collinear domains.
Neutron wavelength, Å
V. Lauter-Pasyuk, H. Lauter, B. Toperverg et al., 1999.
spn
15
State Prize of the Russian Federation in 2000
Development and realization of new methods
in time-of-flight neutron diffraction studies
at pulsed and steady state nuclear reactors
prem
FLNP, JINR
PNPI RAS, Gatchina
RRC KI, Moscow
Victor L. Aksenov
Anatoly M. Balagurov
Vladimir V. Nietz
Yuri M. Ostanevich
Valery A. Kudryashev
Vitaly A. Trounov
Victor P. Glazkov
Victor A. Somenkov
16
Condensed Matter Department at FLNP
Permanent staff
Directorate staff
Ph.D. + students
45
22
13
Doctor of science
Candidate of science
7
26
Main goals:
 Research at the actual fields of condensed matter science and technology.
 Assistance to external users at the IBR-2 spectrometers.
 Operation of spectrometers at the IBR-2 and their further development.
20
A new goal:
 Realization of education program
for young scientists.
18
Age distribution
16
14
14
12
10
8
6
4
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
tit
17
Spectrometers at the IBR-2 reactor
YuMO
HRFD
DIN
KOLHIDA (NP)
DN-2
TEST
Main experimental
techniques at IBR-2:
SKAT
EPSILON
NERA



REMUR
(SPN)

REFLEX
DN-12
KDSOG
IBR-2
Neutron diffraction: 7
SANS: 2
Reflectometry: 2
INS: 3
FSD
IZOMER (NP)
18
Main research topics
Atomic and magnetic structure of new materials.
HRFD, DN-2
Atomic and magnetic dynamics.
DIN, NERA, KDSOG
Non-crystalline materials, liquids, polymers, colloidal solutions.
YuMO
Surfaces, nanostructures of low dimension.
REMUR, REFLEX
Biological materials and macro-molecules.
YuMO
High pressure physics.
DN-12, DN-2
Internal stresses in industrial materials and components.
HRFD, FSD
Texture and properties of rocks.
SKAT, EPSILON
Tem
19
Mercury based high-Tc superconductors.
Collaboration FLNP – MSU (Moscow)
hg5f-c
Normalized intensity
Hg-1201
n(O3)=0.12
0.8
0.9
1.0
1.1
5
0
-5
0.8
1.0
1.2
1.4
1.6
1.8
2.0
d, Å
Rietveld refinement of HgBa2CuO4.12 structure; IBR-2, HRFD
Rietv
20
The temperature of SC phase transition at HgBa2Cu(O/F)4+
as a function of oxygen / fluorine content
110
100
Tc, K
90
fluorine
oxygen
Тhe temperature of
phase transition
depends on charge!
80
70
60
50
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
Extra oxygen / fluorine content
Hg-Tc
21
Interatomic (apical) distances in HgBa2CuO4(O/F)
2.04
HgCuO2
oxygen
2.82
fluorine
2.02
2.80
2.00
2.78
1.98
Hg - O2 (Å)
Cu - O2 (Å)
1.96
1.94
0.00
2.76
Apical distances
depend on the
amount of anions!
2.74
0.05
0.10
0.15
0.20
0.25
0.30
0.35
2.72
0.40
Extra oxygen / fluorine content
From: A.M. Abakumov et al.,
PRL 80 (1998) 385.
Hg-F-dist.
22
Colossal_Magneto_Resistivity (CMR) – effect in
T1-xDxMnO3 manganites, T = La, Pr, D = Ca, Sr.
Electrical resistivity decreases in 107 times under the influence
of magnetic field!
cmr
23
Giant oxygen isotope effect in (La0.25Pr0.75)0.7Ca0.3MnO3
(LPCM-75)
resis-c
1E+8
(La0.25Pr0.75)0.7Ca0.3MnO3
1E+7
(La0.25Pr0.75)0.7Ca0.3MnO3, isotope enriched:
18O, 75%
(O-18) insulating down to 4 K
16O, 99.7%
(O-16) metallic at T<100 K
O-18
r ( cm)
1E+6
1E+5
1E+4
O-16
1E+3
(La0.25Pr0.75)0.7Ca0.3MnO3, O-18
1E+2
la-o18c
1E+1
Normalized neutron counts
HRFD
T=293 K
60
80
100
120
140
160
180
Temperature, K
N.A. Babushkina et al.,
Nature 391 (1998) 159
0.8
0.9
1.0
1.1
1.2
1.3
1.4
5
0
-5
0.8
LPCM/Samples
1.0
1.2
1.4
1.6
1.8
d, Å
2.0
2.2
2.4
2.6
2.8
24
Giant oxygen isotope effect in (LPCM-75). Lattice parameters.
TFM TAFM TCO
7.695
Lattice parameters (Å)
O-18
b'
7.690
16O
O-16
7.680
ac-75c
a
Lattice parameters (Å)
/ 18O (O-16 / O-18)
7.685
7.675
5.460
5.455
O-16 / O-18
5.450
c
5.445
O-18
Temperature dependencies of
lattice parameters a and c
(bottom) and b (top) for the O16 and O-18 samples. The
vertical lines mark the
temperatures of CO, AFM, and
FM transitions. Between TFM
and room temperature the
parameters of both samples are
coincide.
5.440
O-16
5.435
0
16O
(La0.25Pr0.75)0.7Ca0.3MnO3,
b-75c
/ 18O – Latt. Param.
50
100
150
200
Temperature (K)
250
300
25
Giant oxygen isotope effect in (LPCM-75). Structural parameters.
angsr-c
158.0
<Mn-O-Mn> (degr.)
O-16
157.5
157.0
156.5
O-18
TFM (O-16)
156.0
0
50
100
150
200
250
300
mno1-c
1.970
Interatomic distances and
valent angles changes after
oxygen isotope (16O→18O)
exchange in LPCM-75.
<Mn - O> (Å)
O-18
1.965
1.960
TFM (O-16)
O-16
1.955
0
50
100
150
200
250
300
Temperature (K)
16O
/ 18O
26
Neutron diffraction: an effective, nondestructive technique
for determining residual stresses (applied research).
n

Detector 2
Q2
component
(sample)
incident neutron beam

diaphragm
Q1
Detector 1
0
Diffraction experiment for
measuring of internal stresses
inside material or component:
• highly accurate,
• completely nondestructive,
• multi-phase materials,
• in situ mode.
gauge volume
By two detectors at 90 one can measure stresses in both Q1 and Q2 directions simultaneously.
shema
27
Loading device “TIRAtest”
Typical shape and size of a sample
Stress rig on neutron beam
Tar-1
Tensile grip design
28
Residual stresses in bimetallic steel-zirconium adapter
steel
Bimetallic adapter placed at
HRFD
adapter
Zr
Cross-section of bimetallic adapter
wall
29
Residual stresses in bimetallic steel-zirconium adapter
11
3
10
10
2
9
8
9
8
0
7
7
1
6
5
5
1
4
33
6
2
Y / mm
Y / mm
11
0
3
-1
2
1
4
3
37
2
31
35
1
-2
29
0
0
0
0
1
2
3
4
5
1
2
3
4
5
X / mm
X / mm
Axial deformation map for steel region.
The first zirconium screw tooth: Y=0; X=5.
Karta-1
The diffraction (111) peak width distribution
for steel region.
30
Condensed Matter Division & IBR-2:
Last 5 years Ph.D. thesis.
1. V.V. Luzin “Texture in bulk samples: experimental and model investigation”
NSVR & SKAT, 1999.
2. V.Yu. Kazimirov “New ferroelectrics – ferroelastics (CH3)2NH2Al(SO4)26H2O”
NERA, 1999.
3. О.V. Sobolev “Inelastic neutron scattering by water solutions and micro-dynamics
of hydration”
DIN, 2000.
4. А.N. Skomorokhov “Phonon-maxon area in excitation spectra of liquid helium”
DIN, 2000.
5. D.V. Sheptyakov “Structural peculiarities of complex copper oxides
superconductors”
HRFD & DN-12, 2000.
6. D.P. Kozlenko “Structure and dynamics of ammonium halides”
DN-12, 2001.
Tem
31
Condensed Matter Division & IBR-2: Last 5 years Ph.D. thesis.
7. Т.А. Lychagina “Texture and elastic properties of materials: neutron diffraction
studies”
SKAT, 2002.
8. S.V. Kozhevnikov “Effect of spatial splitting of polarized neutron beam:
investigation and application”
SPN, 2002.
9. G.D. Bokuchva “Neutron diffraction studies of internal stresses in bulk materials”
HRFD, 2002.
10. D.Е. Burilichiev “Texture and elastic anisotropy of earth mantle rocks
at high pressure”
SKAT, 2002.
11. М.V. Avdeev “The investigation of the fractal properties of global proteins
surface”
YuMO, 2002.
12. V.I. Bodnarchuk “Interaction of polarized neutrons with non-collinear
magnetic structures”
REFLEX, 2003.
13. А.Kh. Islamov “Structure and properties of lipid membranes: neutron
diffraction studies”
Tem
DN-2, YuMO, 2003.
32
User program at the IBR-2 spectrometers
Experts’ commissions
Diffraction:
H. Tietze-Jaensh, Germany
P. Mikula, Czech Rep.
V.A. Somenkov, Russia
Inelastic Scatt.:
P. Alexeev, Russia
W. Zajak, Poland
I. Padureanu, Romania
Neutron optics:
H. Lauter, France
D.I. Nagy, Hungary
A.I. Okorokov, Russia
SANS:
G. Pepy, France
A.N. Ozerin, Russia
J. Pleshtil, Czech. Rep.
J. Teixeira, France
User-Pr
Time-sharing (14 spectrometers)
FLNP (35%)
External
fast (10%)
External
regular (55%)
User statistics
Others, 19%
FLNP, 25%
France, 3%
Poland,
5%
Germany,
17%
Russia, 31%
33
Conclusions
Neutron scattering at the IBR-2 has the excellent present
and good prospect for future because:

IBR-2 is one of the best neutron sources for condensed matter studies;

Parameters and performance of neutron spectrometers at the IBR-2
are at a world top level;

There exists a realistic program for development of spectrometers;

The staff is well experienced and there is a good balance between
aged and young scientists;

Tem
There exists a good collaboration with many Institutions.
34
END
35
Our problems
1. Neutron guide tubes.
20000
2. Detectors.
vv-1
DN-12
1 - 1996
2 - 1997
18000
16000
14000
Intensity
15
10
2
12000
Gain
10000
1
8000
5
6000
4000
2000
0
0
0
1
2
Wavelength, Å
3
DN-12 diffractometer: intensity
gain-factor after installation
of a neutron guide tube.
Tem
4
Multi-element back-scattering
detector for FSD diffractometer.
36
The first steps of TOF neutron scattering
for condensed matter research in FLNP (1963 – 1980)

The first TOF diffraction patterns obtained at a pulsed neutron source
(Buras, Nietz, Sosnovska, 1963).
Tem

Inverted geometry for inelastic scattering (Bajorek, 1964).

Geometrical focusing in TOF diffraction (Holas, 1966).

Diffraction and inelastic scattering with pulsed magnetic field (Nietz, 1968).

Comb-like neutron moderator (Nazarov, 1972).

The first TOF structural experiment (Balagurov, 1975).

The first TOF SANS (small-angle) experiment (Ostanevich, 1975).

Correlation spectrometry at pulsed neutron source (Kroo, 1975).

The first 2D & 3D TOF diffraction patterns (Balagurov, 1977, 1980).

Axial geometry for SANS (Ostanevich, 1978).

Spin-flipper with extended working area (Korneev, 1979).
37
Development of TOF technique for condensed matter research
at the IBR-2 in 1981 – 2003
The first mirror polarizer for TOF spectrometer (Korneev, 1981).


Neutron guide tubes for pulsed neutron source (Nazarov, 1982).

Axial geometry for SANS (Ostanevich, 1982).

The first real-time TOF experiments with ts1 min. (Mironova, 1985).

Fourier-diffractometer at pulsed neutron source
(Aksenov, Balagurov, Trounov, Hiismaki, 1992).

The first TOF experiments with sapphire-anvil high pressure cell
(Somenkov, Savenko, 1993).
Tem

Inelastic scattering experiments at TOF reflectometer (Korneev, 1995).

Combined electronic & geometrical focusing (Kuzmin, 2001).
38
The most important parameters of a pulsed source
for neutron scattering experiment
Pulsed source

Spectrometer

Experiment



Average power
Intensity
Duration
Pulse width
Resolution
Quality of data
What does it mean for the IBR-2 ?
Diffr.-IBR2
39
Diffractometers at the IBR-2
1. HRFD – high resolution Fourier diffractometer
crystal structure of powders
2. DN-2 – multi-purpose diffractometer
single crystals, magnetic structures, real-time studies
3. DN-12 – diffractometer for microsamples
high pressure experiments
4. FSD / EPSILON – stress diffractometers
internal stresses in bulk samples
5. SKAT / NSVR – texture diffractometers
texture of rocks and bulk samples
Diffr.-IBR2
40
Radiations for diffraction studies of internal stresses
Radiation
Accessibility
Resolution Resolution
Scanning
Experiment
over d
over x
depth
geometry
----------------------------------------------------------------------------------------------------------------X-ray
+++++
+++
+++
Synchrotron
radiation
++
+++++
+++++
+
+++
+++
++
++
++
+
+++++
+++++
----------------------------------------------------------------------------------------------Neutron
With TOF neutron diffractometer (pulsed neutron source)
determination of stress anisotropy is possible!
izluch
up to 3 cm in steel,
6 cm in Al
41
Peak shift under loading for d/d ≈ 0.001
-Fe
(110)
fe-str
(a-a0)/a0=0.001
(200 MPa)
(a-a0)/a0=-0.0001
(20 MPa)
2.020
2.030
2.025
2.035
d, Å
Peak shift for E=200 GPa and loading of 20 MPa and 200 MPa
sdvig
42