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PROJECT REPORT ON

OPTICAL STUDY OF CO-PRECIPITATED CERIUM MOLYBDO IODATE AND CERIUM MOLYBDO PHOSPHATE NANOPARTICLES

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CHAPTER 1

NANOSTRUCTURED MATERIAL-A BRIEF

INTRODUCTION

1.1. Nanotechnology and Nanomaterials : An introduction

The roots of Nanotechnology and Nanomaterials can be traced to a lecture delivered by

Richard Feymann(Nobel Laureate) in 1959 in a meeting of American physical society, when he

speculated this future scientists and engineers would build structures from atoms and

molecules(1). He gave a talk, "There's Plenty of Room at the Bottom," at an American Physical

Society meeting at caltech. Nanotechnology shortened to "nanotech", is the study of

manipulating matter on an atomic and molecular scale. Generally, nanotechnology deals with

structures sized between 1 to 100 nanometre in at least one dimension, and involves

developing materials or devices possessing at least one dimension within that size. Quantum

mechanical effects are very important at this scale, which is in the quantum realm.The Greek

word “nano” refers to a dimension ,one thousand times smaller than a micron.

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Richard Feymann

Although nanotechnology is a relatively recent development in scientific research, the

development of its central concepts happened over a longer period of time. The emergence of

nanotechnology in the 1980s was caused by the convergence of experimental advances such as

the invention of the scanning tunneling microscope in 1981 and the discovery of fullerenes in

1985, with the elucidation and popularization of a conceptual. framework for the goals of

nanotechnology beginning with the 1986 publication of the book Engines of Creation.

The scanning tunneling microscope, an instrument for imaging surfaces at the atomic level, was

developed in 1981 by Gerd Binnig and Heinrich Rohrer at IBM Zurich Research Laboratory, for

which they received the Nobel Prize in Physics in 1986. Fullerenes were discovered in 1985

by Harry Kroto, Richard Smalley, and Robert Curl, who together won the 1996 Nobel Prize in

Chemistry.

Around the same time, K. Eric Drexler developed and popularized the concept of

nanotechnology and founded the field of molecular nanotechnology. In 1979, Drexler

encountered Richard Feynman's 1959 talk "There's Plenty of Room at the Bottom". The term

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"nanotechnology", originally coined by Norio Taniguchiin 1974, was unknowingly appropriated

by Drexler in his 1986 book Engines of Creation:

One of the problems facing nanotechnology is the confusion about its

definition. Most definitions revolve around the study and control of phenomena and materials

at length scales below 100nm and quite often they make a comparison with a human hair,

which is about 80000nm wide. There has been much debate on the future implications of

nanotechnology. Nanotechnology has the potential to create many new materials and devices

with a vast range of applications, such as in medicine,electronics and energy production.

Nanomaterials is a field that takes a materials science-based approach to nanotechnology. It

studies materials with morphological features on the nanoscale, and especially those that have

special properties stemming from their nanoscale dimensions. Nanoscale is usually defined as

smaller than a one tenth of a micrometer in at least one dimension,[2 ] though this term is

sometimes also used for materials smaller than one micrometer.

Nanomaterials (nanocrystalline materials ) are materials possessing grain sizes of the order

of a billionth of ammeter.A nanocrystalline material has grains of the order of 1-100 nm.The

average size of an atom is of the order of 1 to 2 Angstroms in radius. 1 nanometer comprises 10

Angstroms; hence in one nm there may be 3 to 5 atoms,depending on their radii.

Nanocrystalline materials are exceptionally strong,hard, and ductile at high

temperatures,wear resistant,corrosion resistant, erosion resistant & chemically very active.

1.2. Classification of nanomaterials.

1.2.1. On the basis of dimension

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Nanostructured materials are Classified into four different

categories depending on their physical dimensions.

They are

a. Nanomaterials in zero dimension(clusters)

This is the recent type of the nanostructured materials. The zero dimensional clusters

are being investigated to tailor optical properties. Solgel process has been commonly used to

generated clusters.The typical method of synthesis of the recent zero dimensional

nanostructured materials are the solgel process.They are also called quantum dots.

b. Nanomaterials in one dimension:

One dimensional nano structure has been called by a variety of names including

whiskers,fibres or fibrids,nanowires or nanorods.One dimensional nanostructured materials

there will be a layered structure or a lamellar structure.Vapour deposition, sputtering

techniques and electro deposition techniques have been used to synthesize the one

dimensional layered nanostructured materials.The magnitude of length & width are much

greater than the thickness of the layered nanocrystals. Monolayer’s(layers that are one atom or

molecule) are also routinely mace & used in chemistry.

c. Nanomaterials in two dimension:

In this nanostructured materials synthesized are filamentary in nature.The length

substancially larger than the width or dimeter in filamentary nanocrystals. Two dimensional

nanomaterials includes tubes & wires.Because of filamentary nature,this type of

nanostructured materials is referred to as two dimensional.The typical method of synthesis of

two dimensional nanostructured material is chemical vapour deposition.(CVD)

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Nanowires

Nanowires are ultrafine wires or linear arrays of dots,formed by self assembly.They can

be made from a wide range of materials.Semiconductor Nanowires made of silicon,gallium

nitride & indium phosphide have demonstrated remarkable optical,electronic & magnetic

characteristics.

d. Nanomaterials in three dimension

The nanostructured materials are basically in equiaxed in and are hence called as

nanocrystallites or three dimensional nanostructured.The methods commonlyemployed to

synthesis nanocrystalline phase in a variety of materials are gas condensation,mechanical

alloying & chemical precipitation and spray conversion prosessing technjques.

1) Nanoparticles.

Nanoparticles are sized between 1&100nms. Nanoprticles may or may not exhibit

size related properties that differ significantly from those observed in fine particles or bulk

materials.

Nanoclusters have atleast one dimension between 1&10nms and anarrow size

distribution.Nanopowders are agglomerates of ultrafine

Particles, nanoparticles or nanoclusters.Nanometer sized single crystals,or

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single domain ultrafine particles are often referred to as nanocrystals . Nanoparticles research

is currently an area of intense scientific interest due to a wide variety of potential applications

in biomedical,optical & electronic fields.

2) Fullerene

A fullerene is any molecule composed entirely of carbon, in the form of ahollow

sphere ,ellipsed,or tube.Spherical fullerenes are also called Carbon nanotubes or buckytubes.

Fullerenes are similar in structure to graphite,which is composed of stacked graphine sheets of

linked hexagonal rings .

Fig.1.1 Fullerene

3) Den drimers

Den drimers are spherical polymeric molecules,formed through a

nanoscale ,hierarchial self assembly process.There are many types of den drimers ; the smallest

is several nanometers in size. Den drimers are used inconventional applications such as

coatings & links.

4) Quantum dots.

Nanoparticles of semiconductors(quantum dots) were theorized in the 1970s and

initially created in early 1980s.If semiconductors particles are made small enough, quantum

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effects come into play ,which limit the energies at which electrons & holes can exist in the

particles.

Fig 1.2

Fig1.2. represents the schematic representation of the four different types of nanostructured

materials.

1.2.2 Phase composition

According to phase composition nanostructured materials are classified into 3

groups.They are

Single phase solids Crystalline ,amorphous particles &

Layers etc.

Multi phase solids Matrix composites,coated particles etc.

Multi phase systems Colloids,aerogels,ferro fluids etc

Table 1.2.2.Classification based on phase composition.

1.2.3 Manufacturing process

Gas phase reaction Flame synthesis,condensation,CVD etc

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Liquid phase reaction Solgel,precipitation,hydrothermal

processing etc.

Mechanical procedures Ball milling,plasyic deformation etc

Table 1.2.3.Classification based on manufacturing process.

1.3. Properties of Nanostructured MaterialsOwing to the very fine grain size, nanostructured materials exhibit a variety of

properties that are different and often considerably improved in comparison with those of

conventional coarser grained polycrystalline materials. If the size of the atomic ensemble

becomes comparable to or smaller than the typical length scale of a physical phenomenon,

then the spatial confinement can affect any property. Some of the properties of

nanostructured materials are given below.

(a). Mechanical Properties

Elastic constants of nanocrytstalline materials have been reduced considerably

compared to those of bulk materials. This is due to the comparatively higher inter-atomic

spacing in the boundary regions. The strength of nanocrystalline material increases

considerably than that of coarse-grained material. Hardness also increases with decreasing

grain size in conventional coarser grained materials. This relationship is called Hall-Petch

relationship5. For nanocrystalline materials hardness decreases with decrease in grain size. It is

referred to as inverse Hall-Petch effect. In some grains, direct relationship between Young’s

modulus and hardness has been established. Reducing the grain size can lower the

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ductile/brittle transition temperature. The fracture stress of nanocrystalline material is lower

than that of conventional coarse-grained material. Grain size and shape, their distribution,

pores and their distribution, surface condition, all affect the mechanical behaviour of

nanocrystalline materials.

(b).Thermal Properties

The thermal expansion coefficient of nanocrystalline material is greatly enhanced due to

the presence of large amount of grain boundaries. The specific heat of a material is closely

related to the vibrational and configurational entropy of the material, which is directly related

to the nearest neighbour configuration. The specific heat in nanocrystalline material is much

higher than that in the coarser grained material. The increase in specific heat in nanocrystalline

material is art attributed to the complicated structure of grain and phase boundaries. The

enthalpy and entropy of nanocrystalline material is very high.

(c). Electrical Properties

The electrical resistivity of nanocrystalline metal is higher than in both coarse-grained

polycrystalline metal and alloys. The residual resistivity of nanocrystalline metals of 00K

decreases with an increase in grain size. If the crystal size is smaller than the electron mean

free path, grain boundary scattering dominates and hence electrical resistivity as well as the

temperature coefficient is increased. It has been shown that the AC conducting of

nanocrystalline TiO2 doped with about 1% Pt is reversible with temperature. The magnitude of

electrical resistivity and hence the conductivity in composites can be changed by altering the

size of the electrically conducting component.

(d). Magnetic Properties.

Magnetic Properties of nanocrystalline materials depend on the grain size. It was noted

that with increasing grain size d, the coercivity Hc increases following d6 power law up to 50nm,

runs through maximum of the Hc 30A/cm and then decreases for grain sizes of about 50nm

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decoding to the well known 1/d law for polycrystalline magnets. Nanostructured materials

show a reduction in the saturation magnetization and ferromagnetic transition temperature,

due to the deviations of inter-atomic spacing in the interfacial region.5

Nanocrystalline iron based alloys are used for soft magnetic applications due to their

specific characters like low coercivity, high permeability, zero magnetostriction, low core losses

due to high electrical receptivity and good thermal stability. Magnetic calorific effect is another

important magnetic property of nanocomposites5. The magnetic property of nanosized particle

depends on the large surface to volume ratio. Unlike bulk materials consisting of multiple

magnetic domains, several small ferromagnetic particles can form single magnetic domains,

giving rise to supramagnetism. This behaviour opens the possibly for application in information

storage.

(e). Optical Properties

When the diameter of the nanostructured material is decreased, discrete electronic

energy states are formed. The exciton Bohr radius play the central role in the optical properties

of semiconductor nanostructures, when the size of nanostructure component approaches the

Bohr radius electronic and optical absorption changes and the integrated absorption can

increase. If the crystallite size of a nanocrystalline material becomes comparable or smaller

than de-Broglie wavelength of the charge carriers generated by the absorbed light, the

confinement increases energy required for absorption. This energy increase shifts the

absorption/luminescence spectra towards shorter wavelength (blue). The blue shift is a

quantum size effect. Example: Blue shift is observed in the luminescence spectra of

nanocrystalline ZnO as a function of crystal size.

Controlling particle size can change optical properties of nanostructure samples. By

controlling the cluster size of CdSe, Steigerwald and Burs (1989) were able to synthesize

clusters of very narrow size distributions and show that they indicate varying degrees of

quantum confinement and different band gaps. Clusters of 1.2-1.5nm diameter have a band

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gap of 3eV and those having diameter of 3.5nm have a band gap of 2.3eV while the bulk

material have a band gap of 1.8eV. Due to three dimensional confinements, the mechanisms

for resonant band edge optical non-linearities in nano crystallites are different from those in

bulk materials. Optical and infrared absorption measurements have been performed for nano

crystalline Si film at different temperatures. A pronounced red shift of the absorption was

noticed with increasing temperatures up to 3500C. If deposition temperature was increased to

4000C blue shift was observed which shows the relation between crystal size and deposition

temperature

1.4 Characteristic features of nanostructured materials

In nanostructured materials, two types of atoms can be distinguished crystal atoms and

boundary atoms. Schematic representation of hard sphere model of an equiaxed

nanocrystalline metal is shown in Figure 1.3. and two types of atoms can be distinguished, of

these the first one contains crystal atoms with nearest neighbor configuration corresponding to

the lattice and boundary atoms with a variety of inter atomic spacing differing from boundary

to boundary. A nanocrystaline metal contains a large number of interfaces (~6*1025m-3)with

random orientation relationships and consequently a substantial fraction of atoms lie in the

interfaces. Assuming that grains have the shape of spheres or cubes the volume fraction of the

nanocrystaline materials associated with the boundary can be calculated as 3 ∆/d, where ∆ is

the average grain boundary thickness and d the average grain diameter. Thus the volume

fraction of atoms in the grain boundaries can be as much as 50% for 5nm grains and decrease

to about 30% for 10nm grains and 3% for 100nm grains.

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Figure 1.3

1.5 Applications of nanotechnology

With nanotechnology, a large set of materials and improved products rely on a change

in the physical properties when the feature sizes are shrunk. Nanoparticles, for example, take

advantage of their dramatically increased surface area to volume ratio. Their optical properties,

e.g. fluorescence, become a function of the particle diameter. When brought into a bulk

material, nanoparticles can strongly influence the mechanical properties of the material, like

stiffness or elasticity. For example, traditional polymers can be reinforced by nanoparticles

resulting in novel materials which can be used as lightweight replacements for metals.

Therefore, an increasing societal benefit of such nanoparticles can be expected. Such

nanotechnologically enhanced materials will enable a weight reduction accompanied by an

increase in stability and improved functionality. There are many applicatons of

nanotechnology, few of them are show here.

a. Tissue engineering

Nanotechnology can help to reproduce or to repair damaged tissue. “Tissue

engineering” makes use of artificially stimulated cell proliferation by using suitable

nanomaterial-based scaffolds and growth factors. Tissue engineering might replace today’s

conventional treatments like organ transplants or artificial implants. Advanced forms of tissue

engineering may lead to life extension.

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b. Chemistry and environment

Chemical catalysis and filtration techniques are two prominent examples where

nanotechnology already plays a role. The synthesis provides novel materials with tailored

features and chemical properties: for example, nanoparticles with a distinct chemical

surrounding (ligands), or specific optical properties. In this sense, chemistry is indeed a basic

nanoscience. In a short-term perspective, chemistry will provide novel “nanomaterials” and in

the long run, superior processes such as “self-assembly” will enable energy and time preserving

strategies. In a sense, all chemical synthesis can be understood in terms of nanotechnology,

because of its ability to manufacture certain molecules. Thus, chemistry forms a base for

nanotechnology providing tailor-made molecules, polymers, etcetera, as well as clusters and

nanoparticles.

c. Catalysis

Chemical catalysis benfits especially from nanoparticles, due to the extremely large

surface to volume ratio. The application potential of nanoparticles in catalysis ranges from fuel

cell to catalytic converters and photocatalytic devices. Catalysis is also important for the

production of chemicals.

d. Medicine

The biological and medical research communities have exploited the unique properties

of nanomaterials for various applications. Terms such as biomedical nanotechnology,

nanobiotechnology, and nanomedicine are used to describe this hybrid field. Functionalities can

be added to nanomaterials by interfacing them with biological molecules or structures. The size

of nanomaterials is similar to that of most biological molecules and structures; therefore,

nanomaterials can be useful for both in vivo and in vitro biomedical research and applications.

Thus far, the integration of nanomaterials with biology has led to the development of

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diagnostic devices, contrast agents, analytical tools, physical therapy applications, and drug

delivery vehicles.

e. Filtration

A strong influence of nanochemistry on waste-water treatment, air purification and

energy storage devices is to be expected. Mechanical or chemical methods can be used for

effective filtration techniques. One class of filtration techniques is based on the use of

membranes with suitable hole sizes, whereby the liquid is pressed through the membrane.

Nanoporous membranes are suitable for a mechanical filtration with extremely small pores

smaller than 10 nm (“nanofiltration”) and may be composed of nanotubes. Nanofiltration is

mainly used for the removal of ions or the separation of different fluids. On a larger scale, the

membrane filtration technique is named ultrafiltration, which works down to between 10 and

100 nm. One important field of application for ultrafiltration is medical purposes as can be

found in renal dialysis. Magnetic nanoparticles offer an effective and reliable method to remove

heavy metal contaminants from waste water by making use of magnetic separation techniques.

Using nanoscale particles increases the efficiency to absorb the contaminants and is

comparatively inexpensive compared to traditional precipitation and filtration methods6

f. Information and communication

Current high-technology production processes are based on traditional top down

strategies, where nanotechnology has already been introduced silently. The critical length scale

of integrated circuits is already at the nanoscale (50 nm and below) regarding the gate length of

transistors in CPUs or DRAM devices.

g. Novel semiconductor devices

An example of such novel devices is based on spintronics.The dependence of the

resistance of a material (due to the spin of the electrons) on an external field is called

magnetoresistance. This effect can be significantly amplified (GMR - Giant Magneto-Resistance)

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for nanosized objects, for example when two ferromagnetic layers are separated by a

nonmagnetic layer, which is several nanometers thick (e.g. Co-Cu-Co). The GMR effect has led

to a strong increase in the data storage density of hard disks and made the gigabyte range

possible. The so called tunneling magnetoresistance (TMR) is very similar to GMR and based on

the spin dependent tunneling of electrons through adjacent ferromagnetic layers. Both GMR

and TMR effects can be used to create a non-volatile main memory for computers, such as the

so called magnetic random access memory or MRAM.

In 1999, the ultimate CMOS transistor developed at the Laboratory for Electronics and

Information Technology in Grenoble, France, tested the limits of the principles of the MOSFET

transistor with a diameter of 18 nm (approximately 70 atoms placed side by side). This was

almost one tenth the size of the smallest industrial transistor in 2003 (130 nm in 2003, 90 nm in

2004, 65 nm in 2005 and 45 nm in 2007). It enabled the theoretical integration of seven billion

junctions on a €1 coin. However, the CMOS transistor, which was created in 1999, was not a

simple research experiment to study how CMOS technology functions, but rather a

demonstration of how this technology functions now that we ourselves are getting ever closer

to working on a molecular scale. Today it would be impossible to master the coordinated

assembly of a large number of these transistors on a circuit and it would also be impossible to

create this on an industrial level7.

h. Cosmetics

One field of application is in sunscreens. The traditional chemical UV protection

approach suffers from its poor long-term stability. A sunscreen based on mineral nanoparticles

such as titanium dioxide offer several advantages. Titanium oxide nanoparticles have a

comparable UV protection property as the bulk material, but lose the cosmetically undesirable

whitening as the particle size is decreased.

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i. Energy

The most advanced nanotechnology projects related to energy are: storage, conversion,

manufacturing improvements by reducing materials and process rates, energy saving and

enhanced renewable energy sources.

j. Reduction of energy consumption

A reduction of energy consumption can be reached by better insulation systems, by the

use of more efficient lighting or combustion systems, and by use of lighter and stronger

materials in the transportation sector. Currently used light bulbs only convert approximately 5%

of the electrical energy into light. Nanotechnological approaches like light-emitting diodes

(LEDs) or quantum caged atoms (QCAs) could lead to a strong reduction of energy consumption

for illumination.

1.6 Present Work

Nanomaterials have fascinated scientific community in recent past. Nanosized materials

are those which have particles-organic, inorganic or combinations that are of nanometer size.

These materials exhibit unusual properties compared to their bulk counterparts. The synthesis

of nanomaterials with uniform particle size is a subject of intensive research in recent times

because of their fundamental scientific interest as well as for technological importance.

Acid salts of metals (TMA salts) are obtained in amorphous and crystalline form. These

compounds have the general formula M(IV)(HXO4)2nH2O where, M(IV)=Ce,Zr,Th,Ti etc

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X=P,Mo,W etc. The properties of the -OH group of above materials can be exchanged for

several cations and thus these materials are termed inorganic ion exchangers. A number of

cation can be exchanged with H+ due to which the material possess cation exchange properties

depending on the stoitiometry of the reagent used, temperature at which they are mixed, rate

of addition, mode of mixing, PH etc. The resultant materials vary in water content, compostition

and crystallinity. Literature shows that these materials are well studied in crystalline and

amorphous forms.

In the present work, nanoparticles of Cerium molybdoiodate and Cerium

molybdophosphate are synthesized by controlled chemical co-precipitation method using

EDTA as the organic templating agent. The as prepared samples are annealed at 5000C for 2

hours. The average crystalline size of both samples are determined from X-ray diffraction line

broadening by using Scherrer equation. The surface morphology and chemical composition of

both samples are obtained from SEM with EDAX techniques. The FTIR spectrum of both

samples are recorded for determining the different stretching and bending frequencies of

molecular groups in the samples.

1.7 Reference

1. (H Gleiter,prog.Mater.Sci.33(1988)223.)

2.Cristina Buzea, Ivan Pacheco, and Kevin Robbie (2007). “Nanomaterials and Nanoparticles:

Sources and Toxicity”.

3.N. Taniguchi (1974). On the ‘Basic Concept of Nano-Technology’. Proc. Intl. Conf.

Prod. London, Part II British Society of Precision Engineering.

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4.Kahn, Jennifer (2006). "Nanotechnology". National Geographic 2006 (June): 98–119.

5.Alivasatos A.P.Johnson K.P, Peng X, Wilson T E, Loweth C J, Schultz P G, Nature, 382 (1996)

609.

6.Sergey P. Gubin (2009). Magnetic nanoparticles. Wiley-VCH.

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CHAPTER-2

CHARACTERIZATION TECHNIQUES

2.1. Introduction

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The nanomaterials can be investigated and characterized using different techniques like

X-ray diffraction (XRD), UV-Visible Spectroscopy(UV-Vis),Infrared Spectroscopy(IR), Scanning

Electron Microscopy(SEM), Tunneling Electron Microscopy(TEM) etc. This chapter briefly

describes the theory and instrumentation of X-ray diffraction analysis, SEM with EDAX

technique and UV-visible Spectroscopy.

2.2. X-Ray Diffraction

2.2(a).Introduction

X-ray Diffraction (XRD) is one of the most versatile and widely employed experimental

techniques for the structural characterization of crystalline materials 1-3. X-ray diffraction

pattern of the sample primarily give information about the different crystalline phases

present4,5 . Therefore, the first step after synthesizing the crystalline sample is to record its X-

ray diffraction pattern. X-ray diffraction is the most convenient indirect method for the

determination of average crystallite size of nanocrystalline samples 6-7.

2.2(b).Theory and Instrumentation

X-ray powder diffraction has been used in two main areas, for the finger print

characterization of crystalline materials and for the determination of their structure. Each

crystalline solid has its unique characteristic X-ray powder pattern, which may be used as a

’finger print’ for its identification. X-ray crystallography can also be used to determine crystal

structure. The measurement of crystalline size of a polycrystalline specimens by means of X-ray

is based on the broadening of diffraction lines when the crystallite size is very fine i.e., less than

10-7m 4,5 . The broadening of diffraction peak can be used to determine the size of the crystalline

sample using the Scherrer equation.

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Scherrer equation is, t = 0.9*l/βhkl*Cos qhkl

Bragg’s law is given by,

2dsinθ = nλ …………………………….. (1)

For first order diffraction,

2dsinθ = λ………………………………… (2)

Multiplying both sides by an integer m such that md =t, thickness of the crystal

2tsinθ =m λ…………………….......... (3)

Eqn(2), can also be interpreted as the mth order reflection from a set of planes with interplanar

distance’t’.

Differentiating both sides of (3), remembering m λ is a constant.

2tcosθ Δ θ +2sin θ Δ t =0………… (4)

Δ θ can be positive or negative. Considering magnitude only (4) leads to

t=Δtsinθ/ Δ θcosθ

Since the smallest increment in ‘t’ is d, using Δ t=d, and substituting λ/2 for dsinθ [from (2)],

we get

t= λ/2Δθcosθ……………………….. (5)

A B B’ A’

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C’

C

D θ+Δθ D’

0

1

2

M’ t=md

N M L L’ N’

θ

.

Figure :2.1

Let θ1 = θ +Δ θ, be the highest possible angle that can be got before complete destructive

interference and let θ2=θ –Δ θ be lowest angle that can be got before complete destructive

interference. Now we can interpret 2Δθ as the angular width of the X-ray diffraction line.

In the X-ray diffractometer what is recorded is the variation in intensity of the diffraction

lines with 2θ, so in the X-ray diffractogram we can see diffracted X-rays over all scattering

angles between 2θ1and2θ2. If we assume a triangular shape for the peak, the full width at half

maximum (FWHM) will be,

β = (2θ1 - 2θ2 ) /2

= θ1-θ2

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=(θ +Δ θ) – (θ –Δ θ)

β = 2 Δ θ……………………………… (6)

Imax

Intensity

Imax/2. ….β….

2θ2 2θ 2θ1

Figure:2.2

Diffraction from finite thickness crystal, substituting β for 2Δθ on (5), we get

t = λ/β Cosθ…………………………….. (7)

This is essentially the Scherrer equation.

A more rigorous treatment (using a Gaussian function, rather than a triangular function) gives,

t = 0.9λ /β Cosθ………………… (8), for spherical crystal of diameter t.

t = k*λ /βhkl *Cosθhkl

Here,t is the average crystallite size normal to the reflecting planes ,k is the shape factor, which

lies between 0.95 and 1.15 depending upon the shape of the grains in the wave length of X-ray

used and βhkl is the Full Width at Half Maximum(FWHM) of the diffraction in radians and θhkl is

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the Bragg angle corresponding to the diffraction line arising from the planes designated by the

Miller indices(hkl)7. Knowing the wave length (λ) of the X-ray and analyzing the spectrum, the

thickness’t’ of the crystalline sample can be determined. The instrument for taking X-ray

diffraction pattern is shown in Figure:2.3.

Figure:2.3.Experimental set up for XRD

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X-Ray diffractometer

2.3. Scanning Electron Microscope with EDAX

2.3.1. Introduction

SEM stands for scanning electron microscope. The SEM is a microscope that uses

electrons instead of light to form an image. Since their development in the early 1950's,

scanning electron microscopes have developed new areas of study in the medical and physical

science communities. The SEM has allowed researchers to examine a much bigger variety of

specimens.

The scanning electron microscope has many advantages over traditional microscopes.

The SEM has a large depth of field, which allows more of a specimen to be in focus at one time.

The SEM also has much higher resolution, so closely spaced specimens can be magnified at

much higher levels. Because the SEM uses electromagnets rather than lenses, the researcher

has much more control in the degree of magnification. All of these advantages, as well as the

actual strikingly clear images, make the scanning electron microscope one of the most useful

instruments in research today.

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Figure:2.4

Morphological studies of the samples are done using scanning electron microscopy. SEM

is a very efficient tool to study the surface textures of materials. Here the surface of the sample

is irradiated with a beam of accelerated electrons. Since electrons have shorter wavelengths

compared to photons, the resolution obtained in SEM is very high compared to that in

conventional optical microscopy. Furthermore, the depth of focus in SEM is much greater than

that achieved in optical microscopy. In addition to the above two factors, it has the advantage

of greater magnifying power and hence SEM has become a very powerful technique to explore

the free surfaces of materials. The energy dispersive spectrum of the sample are also shown

along with the SEM image.

The SEM is an instrument that produces a largely magnified image by using electrons

instead of light to form an image. A beam of electrons is produced at the top of the microscope

by an electron gun. The electron beam follows a vertical path through the microscope, which is

held within a vacuum. The beam travels through electromagnetic fields and lenses, which focus

the beam down toward the sample. Once the beam hits the sample, electrons and X-rays are

ejected from the sample.

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Figure:2.5

Detectors collect these X-rays, backscattered electrons, and secondary electrons and convert

them into a signal that is sent to a screen similar to a television screen. This produces the final

image.

2.3.2.Instrumentation:

Figure:2.6

SEM opened sample chamber

The SEM micrographs of our samples are obtained with a Hitachi Model S-3000H

electron microscope. The electron beam is focused on selected areas of the samples according

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to the requirements and at different magnification. The kinetic energy acquired by electrons in

an electron column, when they are accelerated through an electric field, is transferred to the

sample and its dissipation yields a variety of signals available for analysis of electron from the

highest occupied molecular orbital to the lowest available unfilled molecular orbital. In most of

the cases, several transitions occur resulting in the formation of several bands.

The most important property of a semiconductor nanostructure is its optical behavior to

crystallite size. Optical properties may be absorption, spectral response, photoluminescence,

photoluminescence excitation, electroluminescence and Raman scattering whose optical

properties respond to crystalline size. As the size is decreased, the electronic states are

discretized and results in widening of the band gap and increases the oscillator strength. The

radiative recombination life time of carrier is lowered from nanosecond to picoseconds. These

features known as quantum size effect (QSE) are observed in semiconductor nanocrystals.

2.4. Fourier Transform Infrared Spectroscopy2.4.1. Introduction

Spectroscopy is the study of interaction of electromagnetic radiation with matter.

Infrared Spectroscopy is one of the most powerful analytical techniques which offer the

possibility of chemical identification. One of the most important advantages of IR spectroscopy

over the other usual methods of structural analysis is that it provides useful information about

the structure of molecule quickly. This technique is based on the fact that a chemical substance

shows selective absorption in the infrared region. After absorption of IR radiation, the molecule

of a chemical substance vibrate at many rate of vibration giving rise to packed absorption band,

called IR absorption spectra. Various bands will correspond to the characteristic functional

groups and bond present in a chemical substance. Thus an IR spectrum of a chemical substance

is fingerprint for its identification.

A molecule absorbs radiation only when the natural frequency of vibration of some part

of a molecule is the same as the frequency of the radiation. The molecules vibrate at increased

amplitude. This occurs at the expense of the energy of IR radiation which has been absorbed.

30

In Infra-red spectroscopy, the absorbed energy brings about predominant changes in the

vibrational energy which depend upon:

(a) Mass of the atom present in the molecule(b) Strength of the bond(c) The arrangement of atom within the molecule.

It has been found that no two compounds except the enantiomers can have similar

Infra-red spectra. When infra-red light is passed through sample, the vibrational and rotational

energies of the molecule are increased. Two types of fundamental vibrations are stretching and

bending. In stretching vibrations, the distance between the two atoms increases or decreases

but the atom remain in the same bond axis. But in bending vibrations the position of atoms

changes with respect to the original bond axis. There are two types of stretching vibrations.

Also there are four types of bending vibrations- scissoring, rocking, wagging and twisting.

Another condition for a molecule to absorb IR radiation is its electric dipole. A molecule

can only absorb IR radiation when its absorption causes a change in its electric dipole. A

molecule is said to have an electric dipole, when there is a slight positive charge and a slight

negative charge on its component atoms.

2.4.2. Instrumentation

The apparatus for measuring infrared spectra is different from that for visible and

ultraviolet regions because the optical materials like glass and quartz absorb strongly in the

infrared region. The main parts of an IR spectrometer are as follows.10

(a) The IR radiation source.

(b) The monochromators.

(c) The sample cells and sampling of substances.

(d) Detectors.

31

Figure: 2.7

(a) The IR radiation source

The various popular sources of IR radiations are,

(i) Incandescent lamp

In the near infrared instruments an ordinary incandescent lamp is generally used, which

fails in the far infrared.

(ii) Nernst glower

It consist of a hollow rod which is about 2mm in diameter and 30mm in length, which is

non conducting at room temperature and must be heated by external means to bring it to a

conducting state. The main disadvantage of Nernst glower is that it emit IR radiation over wide

wavelength range, the intensity of radiation constant over long period of time.

(iii) Glower source

It is a rod of sintered silicon carbide which is about 50mm in length and 4mm in

diameter. Unlike the Nernst glower it is self starting and more satisfactory. The main

disadvantage is that it is a less intense source than the Nernst glower.

32

(iv) Mercury arc

It is used in far infrared instrument.

(b) Monochromator

The radiation source emits radiation of various frequencies as the sampling electrons absorbs at

certain frequency. It is necessary to select desired frequency from the radiation source. This

selection is advised by monochromators, which are mainly of two types, prism monochromator

and grating monochromator.

(c) Sample cells and sampling of substances

Sample can be solid, liquid or gas. But it should be contained in a cell transparent to IR

radiation. Sample cells are usually made of alkali metal halides such as sodium chloride,

potassium bromide etc.

Sampling of solids

Four techniques are generally employed for preparing solid samples. These are:

Solid run in solution

If the solution of solid can be prepared in a suitable solvent then the solution is run in

one of the cells for liquids. But this method cannot be used for all solids because suitable

solvent are limited in number and there is no single solvent which is transparent throughout

the IR region.

(ii) Solid films

If the solid is amorphous in nature, the sample is deposited on the surface of KBr or NaCl

cell by evaporation of a solution of the solid.

(iv) Mull technique

In this technique, the finely ground solid sample is mixed with nujol (mineral oil) to

make a thick paste which is then made to spread between IR transmitting windows. When IR

spectrum of a solid sample is taken in nujol mull, absorption bands of the sample that happen

to coincide with the absorption band of the nujol mull will be hidden, but others will be clearly

33

seen in the IR spectrum. This method is good for qualitative analysis but not for quantitative

analysis.

(v) Pressed Pellet technique

In this technique a small amount of finely ground solid sample is intimately mixed with

about 100 times its weight of powdered potassium bromide. The finely ground mixture is then

passed under very high pressure in a press to form a small pellet (about 1-2mm thick and 1cm

in diameter). The resulting pellet is transparent to IR radiation and is run as such.

Advantages

1. KBr pellets can be stored for long period of time.

2. As the concentration of the sample can be suitably adjusted in the pellets, it can be used

for quantitative analysis.

3. The resolution of the spectrum in the KBr is superior to that obtained with mulls.

Disadvantages

1. The high pressure involved during the formation of pellets may bring about polymorphic

changes in crystallinity in the samples, which may cause complication in IR spectrum.

2. This method is not successful for some polymers which are difficult to grind with KBr.

From the above discussion we knows that one may employ the Nujol method for

running crystalline compounds in the solid and may reserve the KBr pellet method for

remaining solid samples.

(d) Detectors

Two main types are in common use, one sensing the heating effect of radiation, the

other depending up on photoconductivity. In the near infrared region photoconductivity cell is

generally used that is the radiation is allowed to fall on photo conducting material and

conductivity of material measured continuously by a bridge network. Usual IR detectors are

thermocouple, thermisters, golay cell, photoconductivity cell, bolo meters etc.

34

2.5. References

1. J S Blackmore, in Solid state Physics, Second Edition, Cambridge University Press, Cambridge

(1985).

2. J P Srivasthava, in Elements of Solid State physics-Prentice-Hall India, New Delhi (2001).

3. C.Kittel, Introduction to solid state physics, Seventh Edition, John Wiley & Sons Inc., Singapore

(1995).

4. N F M Henry, H Lipson and W A bWooster, in Interpretation of X-ray diffraction Photographs,

Mac Milan & Co Ltd., London (1961).

5. B D Cullity, in Elements of X-ray diffraction, I Edition, Addison-Wesley

Company, Inc., Massachusetts (1978).

6. Suryanarayana C., Bull.Mat.Sci. 17 (1994) 307.

7. A Cervellnio, C Giannini, A Guagliardi and M Ladisa, Phy.Rev.B.72 (2005) 035412. (Electronic

version).

8. R Jamutowski,J.R.Ferraro, and D.C Lanski, Spectroscopy,7(1992) 22;

I.R, Altemose, J.Chem.Educ, 63 (1986) A216, A262.

9. Skoog, Holler and Nieman, in Principles of Instrumental Analysis, Fifth edition.

10. G.Aruldhas, Molecular Structure and Spectroscopy, II (2007)198-200.

.

35

CHAPTER-3

SYNTHESIS AND CHARACTERIZATION OF

NANOCRYSTALLINE CERIUM MOLYBDOIODATE

AND CERIUM MOLYBDOPHOSPHATE SAMPLES

36

3.1. Introduction Chemistry has played a major role in developing the materials with new and

technologically important properties. The advantage of chemical synthesis is its versatility in

designing and synthesizing new materials that can be refined into final products. The primary

advantage is that chemical methods offers mixing at molecular level. However the benefits of

employing simple and cost effective chemical processing methods are widely recognized and

appreciated 1-5 .The properties and application of nanoparticles are largely dependent on their

size, shape and textures6. Considerable attention has been drawn towards the size and shape

controlled synthesis of nanostructured materials 1-3. Depending upon the specific requirements

such as material to be synthesized, the grain size and maximum permissible size distribution,

purity of sample required, quality of sample generated etc., different methods are employed

for synthesizing nanophase materials. In the present study, nanocrystalline cerium molybdate

and cerium molybdoiodate were synthesized through controlled chemical precipitation

method.

3.2. Sample preparation and Experimental ProcedureNanoparticles of Cerium Molybdoiodate were prepared by controlled co-precipitation method

using analytical grade chemicals. Sodium Molybdate, Pottasium Iodate and Ammonium ceric

sulphate were used as the starting materials. EDTA was used as the stabilizer. Aqueous

solutions of Sodium Molybdate (0.1M, 50 ml) Ammonium ceric sulphate (0.1M, 50ml)

Pottasium iodate (0.1M, 50ml) and EDTA(0.0125M, 50 ml) were slowly mixed drop wise into a

conical flask and it is stirred well using a magnetic stirrer . This process is to be done in one

hour. The stabilizer EDTA was used to prevent growth and agglomeration of the particles. In

this process the particle size is governed by the experimental parameters like concentration of

the reactants, rate of mixing, pH, Viscosity of the solutions etc7. It is important to note that the

stabilizers used for controlling the precipitation reaction should be easily and completely

removable from the sample so as to avoid any possible contamination of the samples.The metal

molybdoiodate precipitate formed was washed several times in distilled water to free it from

ions and other impurities. The wet precipitate obtained was dried at room temperature and

37

thoroughly ground using an agate motor to obtain the Cerium Molybdoiodate precursor in the

form of a fine powder. The Cerium Molybdoiodte precursor material was treated with 1N

HCl.The acid treated Cerium Molybdoiodate precursor was annealed at 500oC for 2 hours to

prepare nanoparticles of Cerium Molybdoiodate.

Nanoparticles of Cerium Molybdophosphate were prepared by controlled co-precipitation

method using analytical grade chemicals. Sodium Molybdate, Disodium hydrogen otho

phosphate and Ammonium ceric sulphate were used as the starting materials. EDTA was used

as the stabilizer. Aqueous solutions of Sodium Molybdate (0.1M, 50 ml) Ammonium ceric

sulphate (0.1M, 50ml) , Disodium hydrogen othophosphate (0.1M, 50ml) and EDTA(0.0125M,

50 ml) were slowly mixed drop wise into a conical flask and it is stirred well using a magnetic

stirrer . This process is to be done in one hour.The Cerium Molybdophosphate precursor

material was treated with 1N HCl.The acid treated Cerium Molybdophosphate precursor was

annealed 500oC for 2 hours to prepare nanoparticles of Cerium Molybdophosphate.

The sample code was assigned to the four samples along with annealing temperature

and duration of annealing is shown in Table.3.1.

Table.3.1

Sample

codeAnnealing Temperature Duration of annealing

CMI - -

CMI 500 500oC 2hrs

CMP - -

CMP 500 500oC 2hrs

38

3.3. Recording of X-ray Diffraction patternThe X-ray diffraction pattern of the samples CMI,CMI 500,CMP and CMP 500 were recorded

using XPERT-PRO powder diffractometer (PAN analytical, Netherlands) employing Cu- K

radiation .

Figure.3. 1 XRD pattern of CMIMeasurement Conditions: Dataset Name CMI 500File name C:\X'Pert Data\general\S N College\CMI 500.xrdmlComment Configuration=Flat Sample Stage, Owner=User-1, Creation date=10/9/2008 2:19:33 PM Goniometer=PW3050/60 (Theta/Theta); Minimum step size 2Theta:0.001; Minimum step size Omega:0.001 Sample stage=PW3071/xx Bracket Diffractometer system=XPERT-PRO Measurement program=General 10-90, Owner=User-1, Creation date=4/2/2009 12:03:19 PMMeasurement Date / Time 8/17/2011 3:11:11 PMOperator NIISTRaw Data Origin XRD measurement (*.XRDML)Scan Axis GonioStart Position [°2Th.] 10.0194End Position [°2Th.] 89.9874Step Size [°2Th.] 0.0170Scan Step Time [s] 10.3371Scan Type ContinuousPSD Mode ScanningPSD Length [°2Th.] 2.12

39

Offset [°2Th.] 0.0000Divergence Slit Type FixedDivergence Slit Size [°] 0.4354Specimen Length [mm] 10.00Measurement Temperature [°C] 25.00Anode Material CuK-Alpha1 [Å] 1.54060Generator Settings 30 mA, 40 kVDiffractometer Type 0000000011045531Diffractometer Number 0Goniometer Radius [mm] 240.00Dist. Focus-Diverg. Slit [mm] 100.00Incident Beam Monochromator NoSpinning No

Position [°2Theta] (Copper (Cu))

20 30 40 50 60 70 80

Counts

0

20

40

60

80

CMI 500

Figure.3. 2.XRD pattern of CMI 500

Peak List:

Pos. [°2Th.] Height [cts] FWHM [°2Th.] d-spacing [Å] Rel. Int. [%]28.2372 47.68 0.4080 3.15787 100.0056.3435 6.66 0.9792 1.63159 13.9774.7780 7.86 0.2040 1.26856 16.48

40

Figure.3. 3.XRD pattern of CMP

Measurement Conditions:

Dataset Name CMP 500File name C:\X'Pert Data\general\S N College\CMP 500.xrdmlComment Configuration=Flat Sample Stage, Owner=User-1, Creation date=10/9/2008 2:19:33 PM Goniometer=PW3050/60 (Theta/Theta); Minimum step size 2Theta:0.001; Minimum step size Omega:0.001 Sample stage=PW3071/xx Bracket Diffractometer system=XPERT-PRO Measurement program=General 10-90, Owner=User-1, Creation date=4/2/2009 12:03:19 PMMeasurement Date / Time 8/17/2011 3:26:46 PMOperator NIISTRaw Data Origin XRD measurement (*.XRDML)Scan Axis GonioStart Position [°2Th.] 10.0194End Position [°2Th.] 89.9874Step Size [°2Th.] 0.0170Scan Step Time [s] 10.3371Scan Type Continuous

41

PSD Mode ScanningPSD Length [°2Th.] 2.12Offset [°2Th.] 0.0000Divergence Slit Type FixedDivergence Slit Size [°] 0.4354Specimen Length [mm] 10.00Measurement Temperature [°C] 25.00Anode Material CuK-Alpha1 [Å] 1.54060Generator Settings 30 mA, 40 kVDiffractometer Type 0000000011045531Diffractometer Number 0Goniometer Radius [mm] 240.00Dist. Focus-Diverg. Slit [mm] 100.00Incident Beam Monochromator NoSpinning No

Position [°2Theta] (Copper (Cu))

20 30 40 50 60 70 80

Counts

0

20

40

60

CMP 500

Figure.3. 4.XRD pattern of CMP 500

Peak List:

Pos. [°2Th.] Height [cts] FWHM [°2Th.] d-spacing [Å] Rel. Int. [%]25.1729 9.12 0.9792 3.53490 24.1028.8952 33.49 1.1424 3.08744 88.5131.3014 37.84 0.4896 2.85537 100.0041.9456 17.84 0.6528 2.15213 47.1448.1860 17.00 0.6528 1.88697 44.93

42

3.4. DETERMINATION OF AVERAGE CRYSTALLITE SIZE USING

SCHERRER EQUATIONIn this section, the average crystallite size of sample CMI 500 and CMP 500 are

determined from X-ray diffraction line broadening, without taking instrumental correction to

line broadening. Scherrer equation is the simplest method of determining the average size of

nanocrystalline samples from X-ray diffraction line broadening.

Scherrer equation8 is,

t = kλ/ (βhkl) measured*cos Ѳhkl

Here, t -is the average crystallite size normal to the reflecting planes, k- is the shape factor

which lies between 0.95 and 1.15 depending on the shape of the grains (k=1 for spherical

crystallites), λ-is the wavelength of X-ray used and (βhkl) measured is the measured FWHM of the

diffraction line in radians and Ѳhkl is the Bragg angle corresponding to the diffraction line arising

from the planes designated by Miller indices (hkl).9

Table :3.2. Average crystallite size of CMI 500 determined using Scherrer equation

2θ θ βhkl

Crystallite

Size(nm)

Average

Crystallite

Size(nm)

28.2372 14.1186 0.408 2.00773E-0826.097456.3435 28.17175 0.9792 9.20306E-09

74.778 37.389 0.204 4.9012E-08

43

Table :3.3. Average crystallite size of CMP 500 determined using Scherrer equation

2θ θ βhkl

Crystallite

Size(nm)

Average

Crystallite

Size(nm)

25.1729 12.58645 0.9792 8.3126E-09

11.741428.8952 14.4476 1.1424 7.18094E-0931.3014 15.6507 0.4896 1.68504E-0841.9456 20.9728 0.6528 1.30327E-08

48.186 24.093 0.6528 1.33305E-08

RESULTS AND DISCUSSION

The XRD pattern of the samples of both CMI and CMP shows no well-defined peaks,

reveals the particles synthesized was amorphous in nature. The annealed samples of both

materials show some well-defined peaks in the XRD pattern, confirms the crystalline nature of

the samples. The average crystallite sizes of CMI 500 and CMP 500 were calculated from X-ray

diffraction line broadening using Scherrer equation. The average crystallite size obtained for

Cerium molybdoiodate heated at 5000C for2 hours(CMI 500) is 26.0974 nm and that for Cerium

molybdophosphate heated at 5000C for 2 hours(CMP 500) is 11.7414 nm.

3.5. SEM images with EDAX

The surface morphology of the powder samples was characterized by scanning electron

microscope (SEM) JEOL/EO JSM-6390. The energy dispersive analysis of X- rays (EDAX) was

carried out on the samples to ascertain the chemical composition.

44

3.5.1. SEM image of CMI

Figure.3.5

3.5.2. SEM image of CMP

Figure.3.6

45

3.5.3. EDAX of CMI

Figure.3.7

3.5.3. EDAX of CMP

Figure.3.8

RESULTS AND DISCUSSION

The SEM image of the CMI and CMP are reproduced in Figure: 3.5 & 3.6. The

morphology obtained from the SEM image indicates that nanoparticles are agglomerated to

46

spherical shape. The EDAX spectrum of the sample CMI and CMP are shown in Figure: 3.7 &

3.8. From the figure, it is clear that the prepared sample contain no other impurities. The

SEM with EDAX spectrum of CMI contains elements such as Ce, Mo, I and O but CMP

contains elements such as Ce, Mo, O, and P.

3.6.RECORDING OF FTIR SPECTRUM OF THE SAMPLES The infrared spectroscopic (IR) studies of the samples CMI,CMI 500,CMP and CMP 500

were maderecorded using Perkin- Elmer FTIR Spectro Photo Meter in the wavenumber

range 500 and 4000cm-1 by KBr disc method.

404.

8541

9.95

482.

1554

3.2080

9.61

996.

6710

79.3

5

1181

.05

1335

.75

1407

.29

1446

.08

1612

.71

3398

.04

-10

0

10

20

30

40

50

60

70

80

90

100

%T

500 1000 1500 2000 2500 3000 3500 4000

Wavenumbers (cm-1)

Figure.3.9.FTIR SPECTRUM OF CMI

47

606.

17

838.

90

1137

.38

1623

.19

3402

.86

-10

0

10

20

30

40

50

60

70

80

90

100

%T

500 1000 1500 2000 2500 3000 3500 4000

Wavenumbers (cm-1)

Figure.3.10.FTIR SPECTRUM OF CMI 500

Figure.3.11.FTIR SPECTRUM OF CMP

40

3.3

1

54

0.4

5

61

5.1

1

79

9.6

3

10

51.2

4

14

01.7

614

52.2

8

16

25.5

7

23

62.2

3

29

25.7

6

34

27.2

2

-10

0

10

20

30

40

50

60

70

80

90

100

%T

500 1000 1500 2000 2500 3000 3500 4000

Wavenumbers (cm-1)

48

537.

9556

1.83

614.

80

848.

42

949.

49

1047

.26

1626

.17

3407

.61

-10

0

10

20

30

40

50

60

70

80

90

100

%T

500 1000 1500 2000 2500 3000 3500 4000

Wavenumbers (cm-1)

Figure.3.12.FTIR SPECTRUM OF CMP 500

RESULTS AND DISCUSSION

The FTIR spectrum of samples CMI and CMI 500 was reproduced in Figures.3.8 & 3.9.

The broad absorption bands in the region 3398cm-1 ,1612 cm-1, 3402cm-1 & 1623 cm-1 is due to

the valance vibration of occluded/ entrapped water10. The bands around 809 cm-1,543 cm-1,482

cm-1 ,

410 cm-1,838 cm-1 and 606 cm-1 corresponds to the intrinsic stretching vibration of the metal

with oxygen atoms11.The additional weak bands and shoulders inthe spectrum due to the

microstructural formation of the samples.

49

The FTIR spectrum of samples CMP and CMP 500 was reproduced in Figures.3.11 & 3.12.

The broad absorption bands in the region 3427cm-1 ,1625cm-1, 3407cm-1 & 1626 cm-1 is due to

the valance vibration of occluded/ entrapped water10. The bands around 815 cm-1,799cm-1,540

cm-1 ,848 cm-1,614cm-1 , 561cm-1 and 537 cm-1 corresponds to the intrinsic stretching vibration

of the metal with oxygen atoms11.The additional weak bands and shoulders inthe spectrum due

to the microstructural formation of the samples.

3.7.ConclusionNanoparticles of Cerium molybdoiodate and Cerium molybdophosphate were prepared

by the chemical co-precipitation method using EDTA as the organic templating agent. The as

prepared samples was annealed at 5000C for two hours. The XRD pattern of the samples of

both CMI and CMP shows no well-defined peaks, reveals the particles synthesized was

amorphous in nature. The annealed samples of both materials show some well-defined peaks

in the XRD pattern, confirms the crystalline nature of the samples. The average crystallite sizes

of CMI 500 and CMP 500 were calculated from X-ray diffraction line broadening using Scherrer

equation. The average crystallite size of CMI 500 is 26.0974 nm and that for CMP 500 is

11.7414 nm. The SEM with EDAX spectrum of CMI contains elements such as Ce, Mo, O and I

but , SEM with EDAX spectrum CMP contains elements such as Ce, Mo, P and O. From the SEM

image of both samples reveals that the particles are agglomerated into spherical shapes and

the as prepared samples of CMand CMI contains no other impurities. The FTIR Spectrum of

CMI,CMI 500,CMP & CMP 500 were recored and the bands were identified.

50

3.8. Reference1. H Gleiter, Prog.Mater.Sci.33 (1989)223.

2. H Gleiter, Adv.Mater (1992)474.

3. C Suryanarayana, Bull.Mater.17 (1994)307.

4. M Mofitt, H Vali and A Einsenberg, Che.Mater.10 (1998)1021.

5. L Brus, J.Phys.Che.Solids.59 (1998) 459.

6. Ying Zhang, Yu Fang, Shan Wang, Shuya Lin, J.Cis.Elsevier, 272(2004), 321-325.

7. P.Pramanik, Bull.Mater.Sci.18 (1995)819.

8. Harol P Klung and Leroy Alexander, X-ray Powder Diffraction Procedure (John Wiley and Sons, New York) (1954).9. N F M Henry, H Lipson and W A bWooster, in Interpretation of X-ray diffraction

photographs, Mac Milan & Co Ltd., London (1961).10. Zawarch M F M and E I Kheshen A A, British Ceramic transitions, 101 (2002) 71.

11. S.Hafner, Zeit. Kristallogr. 115 (1961) 331.