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Synthesis and Charaterization

of La1-xSrxMnO3 Perovskite

nanoparticles (x from 0 to 0.4)

Presenter : Tran Thi Mai – K55 IP

Supervisor: Dr. Nguyen Hoang Nam

Luu Manh Quynh

Content

Introduction

Experimental

Results and discussion

Conclusion

I. Introduction

1.1. The perovskite structure ABO3

perovskite has cubic structure and the cubic

unit cell has the network parameters is:

a = b = c ;

At the peak position of the cubic is the

cation A that around is the position of the

oxygen anion (located in the center of the

cubic face). The cation B is located in the

center cubic

The most important characteristic of the perovskite structure ABO3 is the

existence of the octahedral BO6

α = β = γ = 90o

I. Introduction

Crystal structure which can be changed from cubic to other formats such as

rhombohedral or orthorhombic when the ion A or ion B is changed by other

elements.

La1-xSrxMnO3 is a perovskite has the types

structure ABO3, in which the La ions are

replaced partially by Sr ions.

Due to structural differences have caused

lattice distortion and make the structure of

materials are changed from cubic to other

formats.

I. Introduction

2. Jahn – Teller distortion

When the doped or replacement, the ideal perovskite crystal structures will be

changed (occurs distortion)

Jahn – Teller effects occurs in a metal ions contained the odd number of the

electronic in the eg levels. However, this effect also occurs in compounds which

have the octahedral structure

Jahn – Teller distortion in the perovskite materials

When the octahedral structure change

will make to the length of association

changed according to the axis

I. Introduction

3. magnetic properties in the perovskite materials system La1-xAxMnO3

LaMnO3 compounds show antiferromagnetic properties due to the super-

exchange interaction (SE) between ions Mn3+. When doped ion alkanline metal

elements A2+ (Sr2+) into position of ions rare earth La3+, to ensure charge

neutralize conditions, the partial charge of ion Mn3+ transfer into ion Mn4+.

While the perovskite manganese not doped have dielectric anti –ferromagnetic

properties, the appearance of Mn4+ make the electrical conductivity increases

and appearance the ferromagnetic properties. When the doped concentration is

increased, the conductivity of the material also increases, up to a certain value,

the material will good conductivity as metal and to express strong ferromagnetic

properties

I. Introduction

5. The fabrication technology

The Solid phase reaction method (ceramic method)

The coprecipitation method

The hydrothermal method

The reaction Milling method

The sol – gel method

I. Introduction

The sol – gel method:

The process of creating materials by the sol - gel method consists of

4 main stages:

Creating solution (sol)

Gelled and shaped

Drying

Conglomeration

Các bước tạo vật liệu bằng phương pháp sol – gel

The main benefits of sol–gel processing are the high purity and uniform

nanostructure achievable at low temperatures.

II. Experimental

1. The instruments and chemicals

chemicals

Lanthanum oxide (La2O3)

Strontium carbonate (SrCO3)

Manganese nitrate (Mn(NO3)2.4H2O)

Citric acid (CA.1H2O)

Nitric acid (HNO3)

instruments

Glass, pipet, Thermometer

Magnetic stirrer (RH basic KTC)

Drying furnace (1350FX – 2E Model)

Calcining furnace (CD 1600X CHIDA

II. Experimental

some image of instruments are used in the process

Magnetic stirrer

(RH basic KTC)Drying furnace

(1350FX – 2E Model)

Calcining furnace

(CD 1600X CHIDA)

II. Experimental

CA

Sr(NO3)2 Mn(NO3)2

La(NO3)3

Stirring at 80oC

Sol gel compoundsxerogel

Fabrication process of material by sol – gel method

Drying Preheating Heating

at 1000o Cat 300o Cat 120o C

2. Fabrication process of material

II. Experimental

3. Some illustrative photos

a) b)

c)

Figure: a) sol is obtained after stirring at 80o C

b) and c) the product respectively obtained after

preheating at 300o C and heating at 1000o C

III. Results and discussion

10 20 30 40 50 60 70 80

0

100

200

300

400

500

x=0.4

In

ten

sit

y (

a.u

)

2(degree)

(102)

(110) (104)

(202)(006)

(204)

(212)(116)

(214) (300)

(220) (208)

XRD patterns of La0.6Sr0.4MnO3 nanoparticles.

1. Analysis of x-ray diffraction diagram (XRD)

III. Results and discussion

10 20 30 40 50 60 70 80

0

100

200

300

400

500

600

700

800

900

Inte

nsit

y (

a.u

)

2(degree)

x=0

x=0.1

x=0.2

x=0.3

x=0.4

(102)

(110) (104)

(202)(006)

(204)

(212)(116)

(214) (300)

(220) (208)

XRD patterns of La1-xSrxMnO3 nanoparticles with x = 0, 0.1, 0.2, 0.3 and 0.4

III. Results and discussion

Table 1. The lattice parameters of the La1-xCaxMnO3 samples

with x from 0 to 0.4

Lattice parametersVolume of cell

unit (Å3)Sample a(Å) b(Å) c(Å)

x=0 5.48 5.49 7.71 231.96

x=0.1 5.54 5.45 7.92 239.13

x=0.2 5.49 5.50 7.76 234.31

x=0.3 5.49 5.48 7.82 235.26

x=0.4 5.47 5.46 7.91 236.24

III. Results and discussion

From XRD using the Debye – Scherrer formula:

Sample d(102) d(110) d(202) d(204)d(212)

d(214)

x=0 29.6nm 17.5nm 30.9nm 28.4nm13.0nm

22.5nm 23.7nm

x=0.1 28.2nm 17.9nm 25.7nm 28.7nm14.7nm

21.3nm 22.7nm

x=0.2 26.7nm 19.3nm 19.5nm 25.5nm17.4nm

14.5nm 20.5nm

x=0.3 24.7nm 19.4nm 18.4nm 24.6nm16.5nm

14.1nm 19.6nm

x=0.4 27.0nm 22.7nm 19.0nm 25.0nm15.8nm

15.4nm 20.8nm

The size of crystallites of La1-xSrxMnO3 with x from 0 to 0.4 as the table 2.

Table 2: Size of crystallites of La1-xSrxMnO3

III. Results and discussion

2. Analysis of Scanning electron micrographs (SEM), and

energy dispersive x – ray spectra (EDS)

SEM image and EDS spectra of the sample without doped (LaMnO3)

III. Results and discussion

SEM image and EDS spectra of the sample La0.9Sr0.1MnO3

III. Results and discussion

SEM image and EDS spectra of the sample La0.8Sr0.2MnO3

III. Results and discussion

SEM image and EDS spectra of the sample La0.7Sr0.3MnO3

III. Results and discussion

SEM image and EDS spectra of the sample La0.6Sr0.4MnO3

III. Results and discussion

a)

d)c)

b)

SEM images of La1-xSrxMnO3

with x = 0.1, 0.2, 0.3 and 0.4

annealed at 1000˚C for 2 h

shown in order from left to

right and top to bottom

IV. Conclusion

In this thesis, we have successfully fabricated La1-xSrxMnO3

perovskite materials that nanoscale by the sol-gel method, doped

with Sr ratio from x = 0.1 0.4.

The structure analysis shows that the structure of samples is

typical perovskite structure and the Sr was successfully doped into

sample. The structure of sample have small changes with changing

doping ratio x.

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