ivanda eucmos 2004 last

Apr 15, 2023 Ruđer Bošković Institute, Physics of Materials Division, Laboratory for Molecular Physics, Zagreb, Croatia

Determination of Size Distribution of Oxide and Semiconductor Nanoparticles by HRTEM and

Raman Spectroscopy

M. Ivanda

Ruđer Bošković Institute

Zagreb, CROATIA


Outline

Introduction History of Raman scattering on nanosized

particles Theoretical background Experimental Procedure for evolution of particle size

distributions from the Raman scattering data and comparison to the electron microscopy distributions

Some examples of application Conclusion


Croatia


Zagrebcapital of Croatia 900,000 inhabitants 900 years old.


Institute is situated in Zagreb - capital city of Croatia


Structure of Ruđer Bošković Institute

Division of experimental physics Division of materials physics Division of electronics Division of physical chemistry) Division of organic chem. And biochemistry Division of materials chemistry Division of molecular genetics Division of molecular medicine Centre for marine research Centre for marine and environmental

research Division of laser and atomic research and

Development Library Computer centre

• 700 emplyies

• 400 PhD scientist

• 80 physicist


INTRODUCTION

• NANOSIZED PARTICLES HAVE ATTRACTED ATTENTION FROM A FUNDAMENTAL POINT OF VIEW DUE TO DIFERENCES IN THE BASIC ELECTRONIC AND VIBRATIONAL PROPERTIES WITH RESPECT TO BULK SYSTEMS.

• THE SIZE DEPENDENCE OF THE VIBRATIONAL PROPERTIES OF NANOSIZED PARTICLES IS IMPORTANT FOR A BASIC UNDERSTANDING OF THESE MATERIALS AND TO DETERMINE THEIR POTENTIAL APPLICATIONS.

• HIGH RESOLUTION TRANSMISSION ELECTRON MICROSCOPY (HRTEM) IS USUALLY USED FOR A DIRECT EVALUATION OF THE PARTICLE SIZE DISTRIBUTION ON A LOCAL SCALE WITHIN NANOMETER REGIONS. UNFORTUNATELY, THIS TECHNIQUE IS DESTRUCTIVE, TIME CONSUMING, AND GIVES RELATIVELY POOR STATISTICS. IN ADDITION, IT IS INADEQUATE FOR AN IN SITU ANALYSIS.

• HERE, WE WILL SHOW THAT LOW FREQUENCY RAMAN SCATTERING (LFRS) CAN BE A SIMPLE AND POWERFUL TECHNIQUE FOR THE DETERMINATION OF THE PARTICLE SIZE DISTRIBUTION THAT OVERCOMES DIFFICULTIES ASSOCIATED WITH HRTEM TECHNIQUE.


METHODS OF PREPARATION

TiO2 by sol-gel

CdSe by sol-gel in organic matrix CdS in glass matrix


NANO PRECIPITATES FORMED BY ION BEAMS


HISTORY OF RAMAN SCATTERING ON NANOSIZED PARTICLES

First theoretical work by Lamb Proc. London Math. Soc. 13, 189 (1882)

The theory was extended Tamura et al., J. Phys. C 15, 4975 (1982)Montagna and Dusi, Phys. Rev. B 52,

10080 (1995)Duval, Phys. Rev. B 46, 5795 (1992)

The first experimental evidence Duval et al., Phys. Rev. Lett. 56, 2052 (1986)

nc-Ag in alkali halidesG. Mariotto et al., Europhys. Lett. 6, 239 (1988)

nc-Ag in silicaM. Fuji et al., Phys. Rev. B 12, 6243 (1991)

nc-CdSxSe1-x in glass matrix, Tanaka et al., Phys. Rev. B 47, 1237 (1993); K.E. Lipinska-Kalita, G. Mariotto, and E. Zanghellini,Phil. Mag. B 71, 547 (1995); T. Bishof and M. Ivanda, J. Raman Spectr. 27, 297-302 (1996);

nc-TiO2 - free particles, M. Gotic, M. Ivanda, et al., Mater. Lett. 28, 225 (1996), M. Ivanda et al., J. Mol. Struct. 480&481, 645 (1999).

Theory

Experimetal


THEORY Two types of modes, spheroidal and torsional,

were found. The modes are classified according to the symmetry group of the sphere by the labels (l,m) as for the spherical harmonic function Ylm.

The angular number l=0,1,2,... measures the number of wavelengths along a circle on the surface of the particle.

The each mode l is (2l+1) times degenerate. This degenerate modes are marked by the number m.

The l=0 spheroidal modes are purely radial with spherical symmetry.

Duval has shown that only the spheroidal modes of l=0 and l=2 are Raman-active modes. The estimated wave numbers of these modes are

0=S0vl/dc for l=0 2=S2vt/dc for l=2

and vt are the longitudinal and transversalsound velocities, c is the light velocityS0 and S2 are the proportionality coefficient

Shuker and Gammon relation,

- g() is VDOS- C() light-to-vibration coupling coefficient- n(n)+1 is the boson occupation factor C()~-1 by Montagna and Dusi, Phys. Rev. B

52, 10080 (1995) Since each nanocrystal of diameter d vibrate

with its eigen frequency /d, the excess VDOS g() of LFRS peak corresponds to the particle size distribution N(/d):

N(/d)=g()=IR()2

where IR()=ILFR()/(n()+1), and Sv/c

)()(1)(

)( gCn

I


Experimental

TiO2 and SnO2 powder particles were synthesised by sol-gel technique

In order to obtain larger diameters, particles were thermally treated for one hour at the temperatures between 300 and 600 oC

Nc-Si particles were prepared by the LPCVD technique and ion implatation The Raman scattering experiments were carried out under 514.5 nm and 647 nm excitation lines

in the back scattering configuration using a DILOR Z-24 triple monochromator High-resolution transmission electron microscopy (HRTEM) measurements were performed by

using a JEOL JEM 2010, 200 kV microscope with point resolution of 0.19 nm. Dark field micrographs at magnification of 100.000 times, and HRTEM images at magnification of 300.000 and 600.000 times are used for determination of the particles sizes distributions


1. Raman scatterening on powder TiO2 nanoparticles


Procedure for determination of the particle size distribution from the Low Wavenumber Raman Scattering (LWRS)

M. Ivanda, A.M. Tonejc, I. Djedj, M. Gotić, S. Musić, G. Mariotto and M. Montagna, Determination of nanosized particles distribution by low freqyency Raman scattering: Comparison to electron microscopy, In Lecture Notes in Physics: Nanoscale Spectroscopy and Its Applications to Semiconductor Research, Eds.Y. Watanabe, S. Heun, G. Salviati, and N. Yamamoto, Springer Verlag 2002, pp16-27.


TEM of TiO2 nanoparticle – dark field


HRTEM of TiO2 nanoparticles


Comparison of the RAMAN and HRTEM results


Distribution of the size parameter =Sv/c taking the values from the last figure

•From the fit with Normal distribution: =(1.590.14)x105

• Expected values: =1.51x105 for l=2 =2.39x105 for l=0 •The reasons for dissipation of :• poor statistic of HRTEM measurements• the volume of the Raman probe is estimated to 1011 times larger than those of HRTEM• local inhomogenities of the samples that mainly reflects on the HRTEM measurements• since =Sv/c, it could be influenced with the sound velocity inside particles due to surface effects, defects inside particles, etc.

+-


2. nc-SnO2 prepared by sol-gel metodom, TEM

6x


SnO2 – comparison of Raman (line) and TEM (squares) distributions

LFR of nc-SnO2

0 50 100 150

Wavenumber / cm -1

Ram

an I

nt.

/ A

rb.U

.

38

17

LFR of nc-SnO2

0 50 100 150

Wavenumber / cm -1

Red

uced

Ram

an In

t. / A

rb.U

.

Particle distribution of nc-SnO2

0

10

20

30

40

50

60

70

80

0 2 4 6 8 10 12

Diameter / nm

Par

ticle

freq

uenc

y / A

rb.U

.

Expected values: =2.25x105 for l=0 =1.01x105 for l=2

L/T(calc.)=2.23L/T(exp.) =2.24

Result from the fit: =2.10x105

l=0 mode is active


RAMAN SCATTERING FROM NANOPARTICLES IN MATRIX

2/)(

2/ln(5.0 0

D

eDN

DD

C(D)~D, g()~N(1/D)

Assumption of Log-normal distribution for the particle sizes:

dDDNDCn

EI exc )(),(1)(

),(


3. Raman scattering on nc-TiO2 in quartz glass

M. Montagna, E. Moser, F. Visintainer, L. Zampedri, M. Ferrari, A. Martucci, M. Guglielmi and M. Ivanda, J. Sol-Gel Science and Techn. 26, 241-244 (2003).


4. Raman scattering on nc-CdS in quartz glass (Schott glass)

-60 -40 -20 0 20 40 60 80 100 1200

OG 550

OG 570

OG 590

OG 530

GG 495

OG 515

Ram

an In

tens

ity (

Arb

. Uni

ts)

Wavenumber / cm-1

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

0.0 0.1 0.2 0.3

0.4

0.6

0.8

1.0

0.4

0.6

0.8

1.0

/

o

FW

HM

/ o

Ra

ma

n I

nte

nsi

ty (

Arb

. U

nits

)

/o

0 20 40 60 80 100 0 20 40 60 80 100 120

Wavenumber (cm-1)

GG 495D

o=3.8 nm

=0.15

OG 530D

o=3.9 nm

=0.175

OG 550D

o=8.4 nm

=0.15

OG 517D

o=7.1 nm

=0.175 OG 590D

o=5.5 nm

=0.175

OG 515D

o=2.9 nm

=0.175

I VV -

1.8

*IV

H (

Arb

. Un

its)

Fig. 3, Ivanda et al.

M. Ivanda, K. Babocsi, C. Dem, M. Schmitt, M. Montagna, W. Kiefer, Low Wavenumber Raman Scattering From

Nanosized CdSxSe1-X Crystals Embeded In Glass Matrix, Phys. Rev. B 67, 235329-235337 (2003).


Comparison of Raman TEM distributions

0 2 4 6 8 10 12 140

10

20

30

40

50

600

20

40

60

80

100

0

10

20

30

40

0

5

10

15

20

OG 515

Particle Size (nm)

OG 515

TE

M P

artic

le F

req

uen

cy

OG 550

OG 590


SiO2

Silicon or Quartz

Thermal annealing 1h 1100oC

Si implantation 80 keV 1017 cm2

5. Si nanoparticles in glass matrix


Schemattic description LPCVD device

Deposition of silicon nanoparticles by the LPCVD technique


3 layers

HRTEM of nanosized silicon layers


Comparison of RAMAN and HRTEM distributions

LF RAMAN

0 50 100

WAVENUMBER / CM-1

REDU

CED

RAM

AN

INTE

NSIT

Y /

Arb

.u.

SIZE DISTRIBUTIONS

0 5 10 15 20

PARTICLE DIAMETER / NM

IR2

/ A

RB.

U.

A

A

B

B

HRTEM

IPL(B) ~ 1000 x IPL(A)

Expected values: =2.23x105 for l=0 =1.51x105 for l=2

From the fit:=1.50x105

l=2 mode is active


6. Nanoparticles of silicon in silicon matrix

•Bubbles formation in silicon by He-implantation

•With applied He-ion doses above 1x1016 ions/cm2 clusters of vacancies and He atoms are formed

• What happens at lower ion doses ?

100 keV 1x1016 cm-2

40 keV 3x1016 cm-2


Raman scattering on the samples implanted with heliumion doses of 5x1015 cm-2 (below the critical value for bubbles formation)

200 400 600 800 10001

10

100

1000

Lo

g(C

He)

, L

og

(I L

WR)

/ A

rb.

Un

its

Temperature / K

0 100 200 300 400 500 600 7000

20

40

60

80

100

120

140

160

180

200

TO(W)+TA(W) or LO(X)+2TA(L)

TO(X)+TA(X)

i,j,kh

gfed

c

b

a

S

TO()

2TA(W),2TA()

2TA(L)

2TA(X)

Ram

an In

tens

ity (

Arb

. Uni

ts)

Wavenumber (cm-1)

0 100 200 300 400 500 600 7000

20

40

60

80

100

120

140

160

180

200

TO(W)+TA(W) or LO(X)+2TA(L)

TO(X)+TA(X)

i,j,kh

gfed

c

b

a

S

TO()

2TA(W),2TA()

2TA(L)

2TA(X)

Ram

an In

tens

ity (

Arb

. Uni

ts)

Wavenumber (cm-1)

90

100

110

120

130

140

150

200 300 400 500 600 700 800 900 1000

1.0

1.1

1.2

1.3

1.4

1.5

1.6

1.7

D

/ n

m

LW

R / A

rb. U

nits

Temperature / K


Formation of silicon-helium complexes of sizes 1.2~1.5 nm in diameter below the critical implatation doses


CONCLUSIONS

1. THE RAMAN SCATTERING SPECTRA OF FREE AS WELL AS OF NANOPARTICLES EMBEDDED IN GLASS MATRIX ARE POSSIBLE TO ANALYZE IN A MODEL OF CONFINED ACOUSTICAL VIBRATIONS

2. FOR EMBEDDED PARTICLES THE MODEL CALCULATION CONSIDERED HOMOGENOUS BROADENING OF THE CONFINED ACOUSTICAL MODES DUE TO INTERACTION OF PARTICLES WITH MATRIX AND INHOMOGENEOUS BROADENING DUE TO CONTRIBUTION OF RAMAN SCATTERING FROM PARTICLES OF DIFFERENT SIZES

3. THE RESULTS FOR DIFFERENT TYPE OF OXIDE AND SEMICONDUCTOR NANOPARTICLES SHOWED GOOD AGREEMENT WITH DISTRIBUTIONS DETERMINED BY TRANSMISSION ELECTRON MICROSCOPY

5. FOR THE BOTH CASES, OF FREE AND EMBEDDED NANOPARTICLES IN MATRIX,

THE RAMAN SPECTROSCOPY HAS SHOWN TO BE SIMPLE, FAST METHOD THAT MAKES IN SITU MEASUREMENTS POSSIBLE AND ALSO HAS SHOWN FAVORABLE STATISTICAL CHARACTERISTICS DUE TO THE MUCH LARGER PROBE VOLUME


COLLABORATIONS:

Home

Dr. K. Furić / Rudjer Boskovic Institute, Zagreb Dr. S. Musić / Rudjer Boskovic Institute, Zagreb Dr. U. Desnica / Rudjer Boskovic Institute, Zagreb Prof. P. Biljanović Faculty for Electronics and Computing, Zagreb Mr. O. Gamulin / Faculty of Medicine, Zagreb H. Gebavi / Bc.S. Student, Zagreb

Abroad

Prof. M. Montagna, prof. M. Ferrari, prof. G. Mariotto, prof. L. Pavesi, University of Trento, Italy

Prof. W. Kiefer, University of Wuerzburg, Germany

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