This is very intersting power point on ZnO NPs synthesized by me GOVIND SONI and my lab partnes KAUSHAL ,SANEHA & DINESH under the guidance of our PhD scholar Mr.SAHIL & Ms.KIRTI in the CYRSTAL LAB of DR.BINAY KUMAR in Department of Physics & Astrophysics .This presentation basically covers the Introduction to Nanoscience and Nanotechnology and synthesis of Zinc oxide nanoparticles using wet chemical method . its characterization has been done in Msc finals Nanoscience lab using X-Ray Diffraction and Particle size Analyzer.This presentation also contains an advance topic on introduction to Spintronics which is basically the study of internsic spin of electronics and its magnetic moment.I hope it will be an important tool to know about Nanoworld .

1. 1.SYNTHESIS OF ZINC OXIDE NANOPARTICLES
USING
WET CHEMICAL METHOD
&
CHARACTERISATION
BY
X-RAY DIFFRACTION
&
PARTICLE SIZE ANALYSER
GOBINDA
SANEHA JAIN
KAUSHAL
DINESH YADAV
2.INTRODUCTION TO SPINTRONICS

2. • Nanoscience and Nanotechnology.
• Introduction to Zinc oxide.
• Structures OF ZnO
• Physical and chemical properties.
• Methods of synthesis.
• Procedure of Wet chemical method.
• Characterization by using PARTICLE SIZE ANALYSER & XRD.
• Calculations & Result Analysis.
• Applications of ZnO.
• Future of ZnO
• Introduction to SPINTRONICS
• Conclusion
• References
AIM

3. What is nanoscience?
The word itself is a combination of nano, from the Greek “nanos” (or Latin
“nanus”), meaning “dwarf”, and the word "science." Nano refers to 10-
9 power, or one billionth. In these terms it refers to one billionth of a meter,
or a nanometer (nm), which is on the scale of atomic diameters. For
comparison, a human hair is about 100,000 nanometers thick!
Nanoscience is the study of atoms, molecules, and objects whose size is on
the nanometer scale (1 - 100 nm).
INTRODUCTION TO NANOSCIENCE

4. NANOTHECNOLOGY
Nanotechnology is basically the designing, characterization , production and applications of nanostructure ,
devices and systems by controlling shape and size at nanometer scale.

5. • Zinc oxide is white coloured inorganic compound that is insoluble in
water.zinc oxide is a key technology material.it have some unique
properties.
INTRODUCTION TO ZINC OXIDE

6. Properties
Chemical formula ZnO
Molar mass 81.38 g/mol
Appearance White solid
Odor Odorless
Density 5.606 g/cm
3
Melting point 1,975 °C
Solubility in water 0.0004% (17.8°C)
Band gap 3.3 eV
Magnetic susceptibility (χ) −46.0*10
−6
cm
3
/mol
Refractive index(nD) 2.0041

7. STRUCTURES
1) WURTZITE 2) ZINCBLENDE
The Wurtzite structure has a Hexagonal
unit cell with two lattice parameters
a=3.2495A and c=5.2069A in the ratio
c/a=1.633(in an ideal wurtzite structure).
It is characterized by two interconnecting
Sub-lattices of Zn2+ and O2- such that
each Zn ion is surrounded by tetrahedral
O ions and vice versa.
Zincblende structure is stable only
by growth on cubic structure .here
too the zinc and oxide centers are
tetrahedral .This tetrahedral
coordination is typical of sp3 covalent bonding
nature

8. • Most of the II-VI compounds crystallizes in either cubic Zinc blende or
Hexagonal Wurtzite structures where each anion is surrounded by
four cataions at the corner of Tetrahedron and vice versa.
• Hexagonal and zinc blende structures have no Inversion symmetry i.e
Reflection of a crystal relative to any given point does not transfer
into itself.
About structures

9. PHYSICAL PROPERTIES
PHYSICAL
PROPERTIES
WIDE BAND GAP
LARGE
EXCITATION
BINDING ENERGY
HIGH RESISTANCE
N TYPE
DOMINANCE
HIGH THERMAL
CONDUCTIVITY
PIEZOELECTRICITY
&
PYROELECTRICITY
STRONG
LUMINESCENCE

10. WIDE BAND GAP
ZnO is wide band semiconductor of the II-VI semiconductor group. ZnO will be
important for blue and ultraviolet optical devices including LEDs, laser diodes ,
photodetectors. The main advantage of large band gap is higher breakdown
voltages and ability to sustain large electric field and lower electronic noise.
Adding Mg to ZnO increases the band gap, whereas Cd decreases the band Gap.
N-TYPE DOMINANCE
The oxygen vacancies in ZnO are actually +2 charged and thus mainly responsible
for the n-type conductivity as well as the non-stoichiometry of ZnO . ZnO crystal
have almost n-type conductivity ,the cause of which has been a matter of
extensive debate and research
LARGE EXCITON BINDING ENERGY
Exciton energy is similar to BE of an electron and proton in an atom of Hydrogen.
The eletron in a semiconductor or in condensed matter state is excited by a
photon and leaves the valance band of this atom, leaving behind an ‘empty space’
or Hole. The free exciton BE in ZnO is 60meV which is very useful for optical
devices, based on excitonic effects.

11. • HIGH THERMAL CONDUCTIVITY
ZnO has very high thermal conductivity .It is used as an additive in rubber industry .They
protect rubber from fungi and UV light.They are used to increase thermal conductivity of
Tyres.
• PIZEOELECTRICITY & PYROELECTRICITY
The origin of pizeoelectricity lies in its crystal structures. O and Zn atom are Tetrahedral
bonded. The centre of +ve and –ve charges can be displaced by applying pressure and this
diplacement results in local dipole moments. This causes the Pizeoelectric properties.

12. CHEMICAL PROPERTIES
CHEMICAL
PROOERTIES
AMPHOTERIC
ZnO+2HCl ->ZnCl2+H2O
ZnO+2NaOH+H2O -> Na2[Zn(OH)4]
ZnO+H2S -> ZnS+H2O
THERMO-
CHORIC Change colour from WHITE to YELLOW when
heated in air and reverting to white on cooling

13. • AMPHOTERIC
ZnO is an amphoteric oxide. It is insoluble in water but soluble in most the Acids
such as HCl.
Solid zinc oxide will also dissolve in alkalis to give soluble zincates.
It reacts with hydrogen sulfide to give zinc sulfide.
• THERMOCHROMIC
ZnO is relatively soft material with approx. hardness of 4.5 on the Mohs scale. Crystalline
zinc oxide is Thermochromic , changes color from white to yellow when heated in air and
changes into white on cooling. This color change is caused by a small loss of oxygen to
environment at high Temprature.

14. COLOUR CHANGE ON HEATING

16. METHODS OF SYNTHESIS
CHEMICAL
METHODS
BIOLOGICAL
METHODS
PHYSICAL
METHODS

17. BIOLOGICAL METHODS
• Synthesizing nanoparticles using microorganisms and plants
having biomedical applications .
• Environment-friendly, cost- effective, biocompatible, safe, green
approach.
• Synthesis through plants, bacteria, fungi, algae etc.
• Large scale production of ZnO NPs free of additional impurities.
• NPs synthesized from biomimetic approach show more catalytic
activity and limit the use of expensive and toxic chemicals.
• Scientists have reported production of ZnO nanoparticles by
slaughtered goat waste.

18. PHYSICAL METHODS
INDIRECT METHOD DIRECT METHOD
• Metallic Zinc is melted and
vaporized (T>907°C ). Zinc
vapor reacts with oxygen in
air to give zinc oxide.
• Size varies from 0.1 to few
nm.
• High purity
• Zinc precursors are reduced
with carbon heating to
produce zinc vapor which is
then oxidized.
• Low purity

19. CHEMICAL METHODS
Liquid Phase
Synthesis
• Wet Chemical
Method
• Sol-Gel Processing
Gas Phase
Synthesis
• Pyrolysis
• Inert Gas
Condensation

20. Wet Chemical Method-
• In Wet chemical method, a reducing agent is allowed to react with the
zinc salt.
• Precipitate Washed Calcinated NPs
• Procedure –
• Solution A (0.073 mol Zn(Cl)2.6H2O) and solution B (0.03666 mol
NaOH) were prepared.
• Zinc Chloride Solution Sodium Hydroxide Solution
(Dropwise)
(298K )
(Stirring)

21. • Drop wise exothermic reaction.
Zn(Cl)2.6H2O + NaOH  Zn(OH)2 + 2NaCl + 6H2O
• Undisturbed overnight precipitation of Zinc
Hydroxide.
• Supernatant was discarded carefully.
Procedure-

22. • Residue was washed thoroughly till pH became neutral.
• The neutral solution was then heated at 90C to allow dehydration.
Zn(OH)2 +2H2O  Zn2
+ +2OH- + 2H2O  Zn(OH)4
2- +2H+
Zn(OH)2  ZnO + H2O
• ZnO in powder form was obtained by the end of dehydration.
• ZnO powder was calcinated from room temp. to 350 C for 2 hours
and stays at 350 C for 5 hours, them temp. is decreased to 70 C
slowly. Thus, we had sample of 350 C.

23. Advantages of Wet Chemical Method –
• It allows us to control pH, temperature, stirring speed which in turn is
responsible for particle size and shape.
Disadvantages of Wet Chemical Method –
• Very Low Yield. It requires a significant amount of solvent, most of
which is decanted when the synthesis is completed.
• This method does not work well if the reactants have very
different solubility as well as different precipitate rate.

24. Particle Size Analyzer-
Particle Size 0.3nm to 5um
Technology Dynamic Light Scattering &
Static Light Scattering
Sample Cell Type Cuvette
Temperature Range 0C to 90C
Dispersion Type Wet
Zetasizer Nano S90

26. • Dynamic Light Scattering is used to measure particle and
molecule size. This technique measures the diffusion of particles
moving under Brownian motion, and converts this to size and a
size distribution using the Stokes-Einstein relationship.
• Static Light Scattering is used to determine the molecular weight
of proteins and polymers. In this technique, the scattering
intensity of a number of concentrations of the sample is
measured, and used to construct a Debye plot. From this the
average molecular weight and second virial coefficient can be
calculated.

27. What is Dynamic Light Scattering?
The Zetasizer Nano series performs size measurements using a process
called Dynamic Light Scattering (DLS).
Dynamic Light Scattering (also known as PCS - Photon Correlation
Spectroscopy) measures Brownian motion and relates this to the size
of the particles. It does this by illuminating the particles with a laser
and analysing the intensity fluctuations in the scattered light.

28. Scattering intensity fluctuations
If a small particle is illuminated by a light source such as a laser, the
particle will scatter the light in all directions.
If a screen is held close to the particle, the screen will be illuminated by
the scattered light. Now consider replacing the single particle with
thousands of stationary particles. The screen would now show a
speckle pattern as shown below.

29. What causes these bright and dark areas?

30. In the above example we said that the particles are not moving. In this situation
the speckle pattern will also be stationary - in terms of both speckle position and
speckle size.
In practice, particles suspended in a liquid are never stationary. The particles are
constantly moving due to Brownian motion. Brownian motion is the movement
of particles due to the random collision with the molecules of the liquid that
surrounds the particle. An important feature of Brownian motion for DLS is that
small particles move quickly and large particles move more slowly. The
relationship between the size of a particle and its speed due to Brownian motion
is defined in the Stokes-Einstein equation.

31. As the particles are constantly in motion the speckle pattern
will also appear to move. As the particles move around, the
constructive and destructive phase addition of the scattered
light will cause the bright and dark areas to grow and diminish
in intensity - or to put it another way, the intensity appears to
fluctuate.
The Zetasizer Nano system measures the rate of the intensity
fluctuation and then uses this to calculate the size of the
particles.

32. Interpreting scattering intensity fluctuation
data
• Digital correlator- A correlator basically measures the degree of
similarity between two signals over a period of time.
In a typical speckle pattern the length of time it takes for the
correlation to reduce to zero is in the order of 1 to 10's of milliseconds.
The "short time later" will be in the order of nanoseconds or
microseconds!

33. Using the correlation function to get size
information
• If large particles are being measured, then, as they are moving slowly,
the intensity of the speckle pattern will also fluctuate slowly.
• And simarlarly if small particles are being measured then, as they are
moving quickly, the intensity of the speckle pattern will also fluctuate
quickly.

34. Intensity Distribution-
Although the fundamental size distribution generated by DLS is an intensity
distribution, this can be converted to other distributions like Volume Distributions and
Number Distributions.

35. Stoke-Einstein’s Equation-
For Diffusion of Spherical particles through a liquid –
Where
R – Radius of the spherical particle
k – Boltzmann Constant
T – Absolute temp.
D – Diffusion Const.
n – Viscosity of the diffusion medium

36. Electromagnetic Spectrum
10-1 to 10 nm
400 to 700 nm
10-4 to 10 -1 nm
10 to 400 nm
700 to 104 nm
X-ray radiation was discovered by
Roentgen in 1895.
X-rays are generated by bombarding
electrons on an metallic anode
Emitted X-ray has a characteristic
wavelength depending upon which
metal is present.
e.g. Wavelength of X-rays from Cu-
anode = 1.54178 Å
E= hn= h(c/l)
l(Å)= 12.398/E(keV)
NMR
10 um - 10 mm

37. Production of X-Rays
 X-rays are produced by the conversion of the kinetic energy
(KE) of electrons into electromagnetic (EM) radiation.

38. Bremsstrahlung
 A large potential difference is applied across the two electrodes
in an evacuated (usually glass) envelope.
 Negatively charged cathode is the source of electrons (e
-
).
 Positively charged anode is the target of electrons.
 Electrons released from the cathode are accelerated towards
the anode by the electrical potential difference and attain kinetic
energy.

39. Bremsstrahlung
 About 99% of the KE is converted to heat via collision-like
interactions.
 About 0.5%-1% of the KE is converted into x-rays via strong
Coulomb interactions (Bremsstrahlung).
 Occasionally (0.5% of the time), an e-
comes within the proximity of
a positively charged nucleus in the target electrode.
 Coulombic forces attract and decelerate the e-
, causing a significant
loss of kinetic energy and a change in the electron’s trajectory.
 An x-ray photon with energy equal to the kinetic energy lost by the
electron is produced (conservation of energy).

40. Bremsstrahlung
 This radiation is termed bremsstrahlung, a German word
meaning “braking radiation”.
 The impact parameter distance, the closest approach to the
nucleus by the e
-
determines the amount of KE loss.
 The Coulomb force of attraction varies strongly with distance
( 1/r
2
); as the distance ↓, deceleration and KE loss ↑.
 A direct impact of an electron with the target nucleus (the
rarest event) results in loss of all of the electron’s kinetic
energy and produces the highest energy x-ray.

41. Bremsstrahlung
Creates a
polychromatic
spectrum

42. Characteristic Spectrum
 Each electron in the target
atom has a binding energy
(BE) that depends on the shell
in which it resides
 K shell – highest BE, L shell
next highest BE and so on
 When the energy of an
electron incident on the target
exceeds the binding energy of
an electron of a target atom, it
is energetically possible for a
collisional interaction to eject
the electron and ionize the
atom
Characteristic x-ray:
from L → K e-
transition

43. Characteristic Spectrum
 The unfilled shell is
energetically unstable, and
an outer shell electron with
less binding energy will fill
the vacancy.
 As this electron transitions to
a lower energy state, the
excess energy can be
released as a characteristic
x-ray photon with an energy
equal to the difference
between the binding
energies of the electron
shells.
Characteristic x-ray:
from L → K e-
transition

44. Characteristic Spectrum

45. X-ray Tubes
+75 kV-75 kV

46. Powder Diffraction Method
• Requires random orientation
of very fine crystals
• Incident beam of a certain X-
ray wavelength will diffract
from atomic planes oriented
at the appropriate θ angles
for the characteristic d
spacing
• More intense diffraction
peaks for particular angles
that correspond to
characteristic atomic planes

47. • APPLICATIONS OF X-RAY POWDER
DIFFRACTION:
• Characterization of crystalline materials
• Measurement of sample purity
• Determination of unit cell dimension
• STRENGTHS OF X-RAY POWDER
DIFFRACTION:
• Powerful and rapid technique
• Minimal sample preparation required
• Data interpretation is relatively straight forward

48. X-ray Diffraction (Bragg’s Law)
nλ = 2d sinθ
Defines the spacing (d) of atomic planes and incident angle (θ) at
which X-rays of a particular wavelength will reflect in phase (i.e.,
diffract)
GE+EH = nλ
θ’
≠ nλ
GE + EH is the path difference, waves add if equal to nλ

49. Example: Diffraction Patterns
• Each peak represents the solution to Bragg’s law for known radiation
wavelength .
• The unique relationship between such patterns and crystal structures
provide a powerful tool for identification of the phase composition of
powders and polycrystalline materials.

51. Result analysis
FROM XRD-

52. Following observations were made from the peaks –
• The x-ray diffraction peak pattern of the samples was matched with standard data
from the JCPDS (Joint Committee on Powder Diffraction Standards) file of zinc oxide.
The pattern matched exactly with the characteristic peak pattern of Zinc Oxide, thus,
confirming that the particles formed are Zinc Oxide nanoparticles.
• The peaks shifted towards right side of the plot as the temperature increased i.e. the
(2) value corresponding to maxima of the peak increased with increase in
temperature.
• Indexing of the peaks was done using the standard data of Zinc Oxide i.e. the peaks
were labeled by the corresponding miller indices. Maximum peak was observed for
the miller indices (101) . This peak was, therefore, used in the calculation of grain size
of nanoparticles.

53. FROM PARTICAL SIZE ANALYSER

54. Calculations:
• The Scherrer equation, in X-ray diffraction and crystallography, is a formula that relates
the size of sub-micrometre particles, or crystallites, in a solid to the broadening of a
peak in a diffraction pattern. It is used in the determination of size of particles of
crystals in the form of powder.
• The Scherrer equation can be written as:
• 𝐷 =
𝑘𝜆
𝛽𝑐𝑜𝑠𝜃
• where:
• D is the mean size of the ordered (crystalline) domains, which may be smaller or equal
to the grain size;
• k is a dimensionless shape factor, with a value close to unity. The shape factor has a
typical value of about 0.9, but varies with the actual shape of the crystallite;
• λ is the X-ray wavelength;
• β is the line broadening at half the maximum intensity (FWHM), after subtracting the
instrumental line broadening, in radians. This quantity is also sometimes denoted as
Δ(2θ);
• θ is the Bragg angle (in degrees).

55. • The size of ZnO nanoparticles was obtained from Scherrer formula is
24.06nm using maximum peak with miller indicies(1 0 1).
• The size of ZnO nanoparticles was obtained from particle size
analyser is 1123.819 nm.

56. APPLICATIONS OF
ZnO
NANOPARTICLES

58. • In recent times polyvinyl chloride (PVC) has received much more attention and is being
exploited as a polymeric host.
• PVC is a cheap and commercially available polymer.
• It is compatiable with plasticizers such as dibutyl phthalate(DBP),dioctyl adipate
(DOA),polycarbonate(PC) and ethylene carbonate (EC).
• The increasing use of polymer materials such as PVC in hospitals care has led to an
increase in the incidence biomaterials related infections(BIS).
• The adhesion of bacteria to biomaterials led to the formations of biofilms on the
surface ,which play a crucial role in the pathogenesis of BRI.
• Growth and biofilms production protect bacteria from host defense mechanisms and
external agents such as drugs treatments,which makes healing of bacteria infections
quite difficults and require the larger doses or potent antibiotics.
Nano ZnO in pvc

59. • In order to effectively reduce or prevent the biofilms formation,many efforts have
been made to increase the antibacterial properties of the biomaterials.
• Conventional zinc oxide is known as antibacterial agent.Studies have been shown that
the reducing size of zno particles to nanoscale dimensions further increases the
antibacterial properties. Polymer like all biomaterials,are at the risk of harbouring
bacteria that can produce an antibiotic resistant biofilm.
• Addition of ZnO nanoparticles to form a polymer composite material can thus reduce
the activity of undesirable bacteria.

60. • Nanoparticles play an important role in food preservation and packaging and have a
larger work of art and grater potential in food nanotechnology.
• Zinc oxide is not toxic to human and harmfull to microorangism.
• Zinc is a necessary mineral element for human health and ZnO is a daily supplement for
zinc.
• Nanoparticles of ZnO also have good biocompatibility with human cells.
• Currently ZnO is listed as a safe material by food and drug administration(FDA),USA.
Antimicrobial effects

61. ROLE OF ZnO NPS IN AGRICULTURE
• Agriculture is backbone of third world economics but unfortunately now, the agriculture
sector is facing various global challenges like climate changes, urbanization, sustainable use
of resources, and environmental issues such as runoff, accumulation of pesticides and
fertilizers; human population is increasing day by day and food demand is growing rapidly
and estimated population increase in world from current level of 6 billion to 9 billion by
2050 is expected. So we must adopt efficient techniques to make agriculture more
sustainable.
• Nanotechnology has a dominant position in transforming agriculture and food production.
Nanotechnology has a great potential to modify conventional agricultural practices.
Nanoparticles and nanocapsules provide an efficient means to distribute pesticides and
fertilizers in a controlled fashion with high site specificity thus reducing collateral damage.
• Farm application of nanotechnology is gaining attention by efficient control and precise
release of pesticides, herbicides, and fertilizers. Nanosensors development can help in
determining the required amount of farm inputs such as fertilizers and pesticides.
Nanosensors for pesticide residue detection offer high sensitivity, low detection limits,
super selectivity, fast responses, and small sizes. They can also detect level of soil moisture
and soil nutrients. Plants can rapidly absorb nanofertilizers. Nanoencapsulated slow release
fertilizers can save fertilizer consumption and minimize environmental pollution.

62. • Zinc oxide NPs have potential to boost the yield and growth of food crops. Peanut seeds were
treated with different concentrations of zinc oxide nanoparticles. Zinc oxide nanoscale treatment
(25 nm mean particle size) at 1000 ppm concentration was used which promoted seed
germination, seedling vigor, and plant growth and these zinc oxide nanoparticles also proved to
be effective in increasing stem and root growth in peanuts .
• The colloidal solution of zinc oxide nanoparticles is used as fertilizer. This type of nanofertilizer
plays an important role in agriculture. Nanofertilizer is a plant nutrient which is more than a
fertilizer because it not only supplies nutrients for the plant but also revives the soil to an organic
state without the harmful factors of chemical fertilizer.
• One of the advantages of nanofertilizers is that they used in very small amounts. An adult tree
requires only 40–50 kg of fertilizer while an amount of 150 kg would be required for ordinary
fertilizers. Nanopowders can be successfully used as fertilizers and pesticides as well. The yield of
wheat plants grown from seeds which were treated with metal nanoparticles on average
increased by 20–25%.

63. RUBBER MANUFACTURE
Between 50% and 60% of ZnO use is in the rubber industry. Zinc oxide along with stearic
acid is used in the vulcanization of rubber. ZnO additive also protect rubber from fungi
and UV light.
CERAMIC INDUSTRY
• Ceramic industry consumes a significant amount of zinc oxide, in particular in ceramic glaze and
frit compositions.
• The relatively high heat capacity, thermal conductivity and high temperature stability of ZnO
coupled with a comparatively low coefficient of expansion are desirable properties in the
production of ceramics.
• ZnO affects the melting point and optical properties of the glazes, enamels, and ceramic
formulations. Zinc oxide as a low expansion, secondary flux improves the elasticity of glazes by
reducing the change in viscosity as a function of temperature and helps prevent crazing and
shivering.
•

64. By substituting ZnO for BaO and PbO, the heat capacity is decreased and the
thermal conductivity is increased. Zinc in small amounts improves the
development of glossy and brilliant surfaces. However, in moderate to high
amounts, it produces matte and crystalline surfaces.
MEDICINE
• Zinc oxide as a mixture with about 0.5% iron(III) oxide (Fe2O3) is
called calamine and is used in calamine lotion. Two
minerals, zincite and hemimorphite have been historically called calamine.
• Reflecting the basic properties of ZnO, fine particles of the oxide have
deodorizing and antibacterial properties and for that reason are added into
materials including cotton fabric, rubber, oral care products and food
packaging.
• Zinc oxide is widely used to treat a variety of skin conditions, including
dermatitis, itching due to eczema, diaper rash and acne.
• It is used in products such as baby powder and barrier creams to
treat diaper ,rashes ,calamine cream, anti-dandruff shampoos
and antiseptic ointments. It is also a component in tape (called "zinc oxide
tape") used by athletes as a bandage to prevent soft tissue damage during
workouts.

65. CIGARETTE FILTERS
• Zinc oxide is a constituent of cigarette filters.A filter consisting of charcoal impregnated
with zinc oxide and iron oxide removes significant amounts of hydrogen cyanide (HCN)
and hydrogen sulfide (H2S) from tobacco smoke without affecting its flavor.
FOOD ADDITIVE
• Zinc oxide is added to many food products, including breakfast cereals as a source of
zinc, a necessary nutrient. (Zinc sulfate is also used for the same purpose.) Some
prepackaged foods also include trace amounts of ZnO even if it is not intended as a
nutrient.
PIGMENT
• Zinc white is used as a pigment in paints and is more opaque than lithopone but less
opaque than titanium dioxide. It is also used in coatings for paper. Chinese white is a
special grade of zinc white used in artists' pigments. The use of zinc white (zinc oxide) as
a pigment in oil painting started in the middle of 18th century. It has partly replaced the
poisonous lead white and was used by painters such as Böcklin ,Van
Gogh,Manet,Munch and others. It is also a main ingredient of mineral makeup (CI
77947).

66. UV ABSORBER
• Nano-scale zinc oxide and titanium dioxide provide strong protection against UVA
and UVB ultraviolet radiation and are used in suntan lotion and also in UV-
blocking sunglasses for use in space and for protection when welding following research
by scientists at Jet Propulsion Laboratory (JPL).
FUTURE OF ZINC OXIDE
• The future of zinc oxide is going to be fascinating. The potential advances for non-
medicinal applications even surpass that the current medicinal uses. Zinc oxide
NANOROD SENSORS, SPINTRONICS AND PIEZOELECTRICITY are all promising fields and
ones to keep an eye on in the not too distant future.

68. Spintronics
Spintronics is the study of the intrinsic spin of the electron and its associated
magnetic moment.
The spins, being attached to mobile electrons, carry the information along a
wire
Spin orientation of conduction electrons survives for a relatively long time
(nanoseconds, compared to tens of femtoseconds during which electron
momentum decays

69. Principle of spintronics
• Information is carried by orientation
of spin rather than charge.
• Spin can be assume one of the
two states,called spin up spin down.
• The simple method of generating a
spin-polarised current in a metal is
to pass the current through a
ferromagnetic material.

70. Why spintronics?
1. Now the tranistors and other component have reached low dimesnsion and
further reducing the lead to
(i) Sorching heat making the circuit inoperable.
(ii) Also quantum effects comes into play at nanoscale dimesnsions
2. Connection between spin and magnetism
3.Intrinsic connection between spin and quantum mechanics
4..Shortage range of spin-dependent exchange interaction.
5.Issue of speed and power dissipation.

71. Traditional approaches –spin were ignored in transportation.
oAdding the spin degree of freedom to conventional semiconductors
o Increased data processing speed,
oDecreased electric power consumption, and increased integration
densities compared with conventional semiconductor devices.
oMagnetic storage is nonvolatile

72. GMR
• 1988 France, GMR discovery
is accepted as birth of spintronics
• A Giant MagnetoResistive
device is made of at least
two ferromagnetic layers
separated by a spacer layer
• When the magnetization
of the two outside layers is aligned,
lowest resistance
• Conversely when magnetization
vectors are antiparallel, high R
• Small fields can produce big effects

73. No density of states

74. Two currents mode :(a) parallel mode (b)
antiparallel alignment of the magnetisation

75. Perpendicular Current GMR
• Easier to understand theoretically, think of one FM layer as spin
polarizer and other as detector
• Has shown 70% resistance difference between zero point and
antiparallel states
• Basis for Tunneling MagnetoResistance

76. Tunnel Magnetoresistance
• Tunnel Magnetoresistive effect
combines the two spin channels
in the ferromagnetic materials
and the quantum tunnel effect
• TMR junctions have resistance
ratio of about 70%

77. MRAM
• MRAM uses magnetic storage elements instead of electric used in
conventional RAM
• Tunnel junctions are used to read the information stored in
Magnetoresistive Random Access Memory, typically a”0” for zero
point magnetization state and “1” for antiparallel state

78. Spin Transfer
• Current passed through a magnetic field becomes spin polarized
• This flipping of magnetic spins applies a relatively large torque to the
magnetization within the external magnet
• This torque will pump energy to the magnet causing its magnetic
moment to precess
• If damping force is too small, the current spin momentum will transfer to
the nanomagnet, causing the magnetization will flip
• Unwanted effect in spin valves
• Possible applications in memory writing

79. Spin Transistor
• Ideal use of MRAM would utilize control of the spin channels of the
current
• Spin transistors would allow control of the spin current in the same
manner that conventional transistors can switch charge currents
• Using arrays of these spin transistors, MRAM will combine storage,
detection, logic and communication capabilities on a single chip
• This will remove the distinction between working memory and
storage, combining functionality of many devices into one

80. Advantage
• No power failure problem
• No “Boot up” waiting problem
• Less power cosumption
• More compact
• Faster transfer

81. Challenges in this field of spintronics
• Optimization of electron spin lifetimes
• Controlling of the spin for long time
• Difficult to inject and measure spin in nanoscale structures
• transport of spin-polarized carriers across relevant length scales and
heterointerfaces
• Room temperature demonstration of all these spin devices is very
difficult
• Costlier

82. Future scopes
• All the saw devices at nanolevel we can make by taking account of
spintronics.
• It will be a great revolution in Information technology.
• It can replace the electronics industry by a new technology
spintronics .

83. Conclusion
1. Interested bceause of solve the problem of size.
2. It can complete reconstruct the industry.
3. It promise a wide variety of new devices combine logic,logic and sensor
applications.
4. “Spintronic" devices lead to quantum computers and quantum
communication based on electronic solid-state devices, thus
changing the perspective of information technology in the 21st
century.

84. Conclusion
Interest in. spintronics arises, in part, from the looming problem of
exhausting the fundamental physical limits of conventional electronics
However, complete reconstruction of industry is unlikely and spintronics is a
“variation” of current technology
The spin of the electron has attracted renewed interest because it promises
a wide variety of new devices that combine logic, storage and sensor
applications.
Moreover, these "spintronic" devices might lead to quantum computers and
quantum communication based on electronic solid-state devices, thus
changing the perspective of information technology in the 21st century.

85. References
• https://www.nature.com/subjects/spintronics
• http://science.sciencemag.org/content/294/5546/14
• https://en.wikipedia.org/wiki/Giant_magnetoresistance
• http://www.physics.udel.edu/~bnikolic/teaching/ss_spintronics/ss_sp
intronics.html
• https://www.youtube.com/watch?v=cID4fKraWkE&t=3491s
• https://www.youtube.com/watch?v=HB1EUoiWYBg

86. Thank you