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CuO and ZnS samples investigation by small – angle neutron scattering
2013 Practice
for Students from Arab Republic of Egypt at the Joint Institute for Nuclear Research
Dubna, Russia May 12 - June 2, 2013
Diaa Ahmed Rayan1, Shimaa Hamdy Kelany2, EL-Shimaa Moustafa3 1Central Metallurgical Research & Development Institute(CMRDI), EGYPT.
2Egyption Atomic Energy Authority (EAEA), EGYPT.
3Nile University, EGYPT.
Frank Laboratory of Neutron Physics Practice group: YuMO Small – Angle Neutron Scattering Team
Supervisor Dr. Alexander I. Kuklin
Neutron scattering is the process of collision between neutrons emitted by a
source and a target which is the studied sample.
When the scattering angles of these collisions are very small, it is referred to as
Small Angle Neutron Scattering (SANS)
It gives the possibility to study solutions, disordered structures and interactions
between molecules (electrostatic, short range).
We can determine shape, size, volume, internal structure, scattering density,
molecular weight.
Introduction of Neutron scattering
5/31/2013 2
Applications
FERROFLUIDS
Ferrofluids where first researched at NASA. During the space programme of the early 1960’s, the problem arose of how to control the flow of liquid fuel in a zero gravity environment. The solution offered by NASA’s scientists was a new class of materials known as FERROFLUIDS.
The first confirmed application of a ferrofluid was during the APOLLO moon landing projects where the astronaut helmets where sealed using a magnetofluid.
APOLLO rocket during takeoff Ferrofluids in action
In order to ensure stability in a ferrofluid, a good quality coating needs to be applied to the magnetic particles. These coating particles are known as a surfactant. Above we can see the interaction between two particles coated with a surfactant.
If a surfactant is not applied, the interaction between the magnetic particles can lead to the destabilisation of the magnetic fluid, as can be seen in the left picture.
FERROFLUID STABILITY PROBLEM
M.Balasoiu, Magnetic fluids structure and properties
1- possible to measure isotopes and used to measure magnetic materials.
2- Neutrons interact through short-range nuclear interactions. They are very penetrating and do not heat up (i.e., destroy) samples.
3- Neutron energies are comparable to normal mode
energies in materials (for example phonons, diffusive
modes). Neutrons are good probes to investigate the
dynamics of solid state and liquid materials.
4- Neutron wavelengths are comparable to atomic sizes and inter-distance spacing.
Advantage of neutron scattering
Continuous reactors
Most of nuclear reactors is continuous fission mode reactor which neutrons are
one of the fission products, the intensities of the neutron at the sample and the detector are as in the following fig
NEUTRON SOURCE
IBR-2 Pulse Fast Reactor
YuMo
YuMo-SANS Spectrometer (FLNP)
1. Two reflectors 2. Zone of reactor with moderator 3. Chopper 4. First collimator 5. Vacuum tube 6. Second collimator 7. Thermostat 8. Samples table 9. Goniometer 10-11. Vn-standard 12. Ring-wire detector 13. Position-sensitive detector "Volga” 14. Direct beam detector.
Holder for samples
SANS PRINCIPLE • A typical sans result is a graphic of the Scattering
Intensity function of a wavevector Q
• Q is defined as
2
sin
4Q
)()()( QSQPQI
where
•Theta = scattering angle
•Lambda = Wavelength of
incident beam
•The scattering intensity is defined as:
•Where
•Phi = density of particles in volume
•P(Q) = form factor
•S(Q) = structure factor
J. Texeira, Introduction to Small Angle Neutron
Scattering Applied to Colloidal Science, Kluwer
Academic Publishers, Netherlands, 1992
FORM AND STRUCTURE FACTORS
FORM FACTOR
Concerns each particle and is related to its nuclear density
Usually defined as:
Where F(Q) is defined as:
|)(|)( 2QFQP
dVeQF i
particleofvolume
Qr
)()( 0
)(
)( RRQieQS
STRUCTURE FACTOR
Where R is the position vector of a particle inside the compound
Form factor and structure factor
I(Q)=N P(Q) S(Q) (spheres)
SANS (0.01 < Q < 1 nm-1)
* 2D sample , showing different degrees of resolution .
Scattering length density and "contrast"
Large r ↔ Small Q (small spatial resolution) Replace b by the average b of a coherent domain:
iA
i
ibN
M
d
v
b
Example: D2O
Contrast: K ≡ ρ1-ρ2
2101223 10320.610).5805.06674.02(10.620
1.1
cmxx
Contrast variation
CONTRAST VARIATION METHODS
• J.Teixiera., Introduction to SANS applied to colloidal science. *
Project objectives
• structure investigation by SANS method
• Determine the parameters of the structure:
–Radius of gyration
– radii
Applications of CuO and ZnS nanopowders
CuO nanopowders
batteries
magnetic storage media
field emission
Catalysis
ZnS nanopowders
Lasers
Electroluminescence
Gas Sensor Solar Cells
- SANS - XRD (X-ray diffraction)
- SANS - XRD (X-ray diffraction)
Determining Rg using Origin
479627.2
1.0920711.1
3
22971.1
2
th
g
g
R
R
Rtg
tg
CuO nanopowders
Determining Rg using Origin
207564.6
14.0808358.4
3
70677.7
2
th
g
g
R
R
Rtg
tg
CuO nanopowders ZnS nanopowders
• SANS is a powerful method for condensed matter investigation for objects of
sizes between 1 nm to 100 nm – therefore it can be considered a nanoscale
procedure
• The IBR – 2 reactor at the JINR is adequate for SANS machine
• The main parameters and main parts of the YuMO spectrometer have been
studied
• Several applications for SANS exist in the fields of Biology, Chemistry,
Polymers, Ferrofluids, etc.
• A very good method for analysis of density in samples containing more than
one compound is the contrast variation method
• Good programs exist with good mathematical backgrounds for the
reconstruction of the shape of a molecule using data collected from sans
experiments
• It was shown how such a shape can be obtained
CONCLUSIONS
AKNOWLEDGEMENTS
The authors would like to acknowledge Dr. Alexander Kuklin and all members of the Yu/MO Group, Condensed Matter Department.
I wish to express my warm appreciation to Prof. Dr. Jose Teixeira, and Dr. Maria Balasoiu for there assistance, guidance and valuable
advices throughout this school.
We would also like to extend our regards to the organizers of this Practice and all members of the JINR involved with this school.
We would also like to thank the Ambassador of the Arab Republic of Egypt in the Russian Federation and all the members in the embassy
for their kind Reception in the Embassy of Egypt.
REFERANCE
* J. Texeira, Introduction to SmaAngle Neutron Scattering Applied to
Colloidal Science, Kluwer ll Academic Publishers, Netherlands, 1992.
*J.Teixiera., Introduction to SANS applied to colloidal science. * http://www.ncnr.nist.gov/programs/sans/
* http://www.jinr.ru
Contact us: [email protected]