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: diaa001@yahoo.com