Transcript Document

IMNR
Radu R. Piticescu, Roxana M. Piticescu,
National R&D Institute for Non-Ferrous and Rare Metals,
Pantelimon, Ilfov, ROMANIA
Al 5-lea Seminar "Nano" 2 martie 2006
Presentation content
 Introduction
Problems and barriers in development and
applications of hydrothermal procedures for electronic
materials
 Applications in BST ceramics
Applications in Al-doped ZnO
Conclusions and future works
Al 5-lea Seminar "Nano" 2 martie 2006
INTRODUCTION
Nanomaterials market: 490 billion dollars in 2004 and 900 billion dollars in 2005 and 11
trillion dollars in 2010 (annual average grown rate > 10%)
The primary of nanomaterials companies material product types and primary market focuses of
nanomaterials companies
Nanomaterials – the driving force, by Michael J. Pitkethly, Market Report, December 2004.
Al 5-lea Seminar "Nano" 2 martie 2006
INTRODUCTION
Hydrothermal reactions: chemical processes at high pressures and temperatures
over the boiling temperature in aqueous solutions
Solvothermal reactions: chemical processes at high pressures and temperatures in nonaqueous solutions
Hydrothermal reactions between species in hydrothermal solutions
One element
M(II)2+(aq) + 2OH-(aq) = MO+H2O; M(II)=alcaline-earth metals: Mg, Ca, Sr, Ba
2M(III)3+(aq) + 6OH-(aq) = M2 O3 + 3H2O; M(III)= Al, Ga, Ln
M(IV)4+(aq) + 4OH-(aq) = M O2 + 2H2O; M(IV)= Si, Ge, Ti, Zr, Hf, Mn,...
Two elements (ABO3, ABO4,....compounds)
xM(II)2+(aq) +y M(IV)4+(aq) +6(x+y)OH-(aq) = M(II)xM(IVy)O3 + 3(x+y)H2O;
xM(III)3+(aq) + yM’(III)3+(aq) +6(x+y)OH-(aq) =
xM(III)2 yM’(III)2 O3(x+y) + 3(x+y)H2O
Hydrothermal crystallisation: transformation of amorphous species in crystalline
ones (under the influence of temperature and pressure):
M(OH)n = MOn/2 +(n/2) H2O
Al 5-lea Seminar "Nano" 2 martie 2006
Problems and barriers in development and applications
of hydrothermal procedures for electronic materials
STRENGTHS OF HYDROTHERMAL SYNTHESIS
•One step process
•Minimize energy consumption
•Closed systems, low environmental impact
•Products with much higher homogeneity than solid state processing
M.Yoshimura, W.Suchanek, Solid State Ionics 98 (1997), pp. 197-208
Al 5-lea Seminar "Nano" 2 martie 2006
Problems and barriers in development and applications
of hydrothermal procedures for electronic materials
STRENGTHS OF HYDROTHERMAL SYNTHESIS
Any shape, any size (combining with other external driving forces, e.g. electrochemical)
U/I
Hydrothermal deposition
120
PT; PZ; ST; BT
80
60
log K
100
40
20
500
0
400
Cathode
Reference
Anode
Te
300
m
pe
200
ra
tu
re
100
,d
eg
.C
0
Electrophoretic deposition
PT; PZ; ST; BT
R.R. Piticescu, R.M. Piticescu, Workshop
COST D30, Turin, 26-28 Feb. 2004
Al 5-lea Seminar "Nano" 2 martie 2006
Problems and barriers in development and applications
of hydrothermal procedures for electronic materials
WEAKNESSES
• Prediction: Lack of thermodynamic data (only for ideal solutions, low valence ions)
T, p
m[M(OH) n ]z  
 [M(OH2 ) mnq (OH) q ]( mzq )   qH
nJ
 RT ln K j    G (A )
i 1
J
i
0
f
J
i
KJ 
nJ
 (m
 Ai )i , J log Ai = Hi +BZi + Pi
Ai
i 1
Ji is the stoechiometric coefficient of species “i” in the reaction “j”
G0f is the standard free enthalpy of formation of reacting species AJi
mAi is the molar concentration of species Ai the solution
i is the activity coefficient
Lencka and Riman (Rutgers Univ), J.Am.Ceram.Soc, 76, 10, 2649-59 (1993)
Al 5-lea Seminar "Nano" 2 martie 2006
Problems and barriers in development and applications
of hydrothermal procedures for electronic materials
WEAKNESSES
100
70
• Prediction:
Kinetic limitations
t
50

tf
Fc ( t )
100
Fc ( t )
t
 1  3(1   ) 2 / 3  2(1   )
tf
50
150C
0
0
125C
0
0
0
100
Fc ( t )
5000
1 10
t
4
1 10
t
1.5 10
15000
4
4
4
50
100
40
t
 1  (1   )1 / 3
tf
50
200C
0
5000
1.5 10
15000
D (nm)
0
0
0
0
0
0
5000
30
-ln (1-)= kt m
20
10
1 10
t
4
1.5 10
15000
4
0
0
2
4
6
8
10
Time (h)
R.R. Piticescu, C. Monty, D. Taloi, D. Millers,
Sensor and Actuators B, 109 (1), 102-6 (2005)
Roxana M. Piticescu, R. R. Piticescu, D.Taloi, V. Badilita,
Nanotechnology vol. 14 (3), pp. 312-17 (2003)
Al 5-lea Seminar "Nano" 2 martie 2006
Problems and barriers in development and applications
of hydrothermal procedures for electronic materials
OPPORTUNITIES
VERSATILITY:Oxides, non-oxides, organic/biologic materials; hybrid materials
HYDROTHERMAL SYNHTESIS IS ONE OF THE VERY FEW METHODS ABLE
TO GENERATE NEW MATERIALS OR MATERIALS WITH RADICALLY NEW
PROPERTIES
Recent examples: new ultra-hard materials (e.g. BC2N)[1] some of which can be doped for
semiconductor (e.g. p- and n- doped cubic-BN)[2] or opto-electronic (e.g. cubic-Si3N4)[3]
applications,. ANi3+0.98Fe0.02O3 (A=Nd, Lu) perovskites [4] New physical phenomena may be
found, for example the perovskite BiNiO3 (prepared at 60 kbar, 1000 °C) shows a unique transition
between a metallic state, with charge distribution Bi3+Ni3+O3, and a valence disproportionated and
charge ordered insulating state, Bi3+Bi5+(Ni2+)2O6.[5]
[1] Solozhenko,V. L., Dub, S. N. & Novikov, N. Diamond Relat.Mater. 10, 2228–2231 (2001)
[2] Taniguchi, T. et al. Jpn. J.Appl. Phys. 241, L109–L111 (2002).
[3] I.A.Presniakov, G.Demazeau, A.V.Baranov, A.V.Sobolev, K.V.Pokholok., Phys. Rev. B71, 2005, 054409
[4] Gryko, J. et al. Phys. Rev. B 62, 7707–7710 (2000).
[5] Ishiwata S, Azuma M, Takano M, et al, J. Mater. Chem. 12, 3733 (2002).
Al 5-lea Seminar "Nano" 2 martie 2006
Problems and barriers in development and applications
of hydrothermal procedures for electronic materials
Nucleation and growth
-surface diffusion
- continuous growth at the kinks
d
RT
j

(
)
0
dt
z 2 F 2 c cad
-Formation of clusters and critical nuclei
- Formation of monolayrers by layer to layer growth
W(t) = W0 ( 1 - ekt )
Types of morphologies
Unpredictible!
-Layer or platelate growth
- Pyramidal growth
-Whiskeres
-Dendrites
-Epitaxial growth on crystalline substrates
-Oriented growth on polycrystalline or amoprphous
substrates
Al 5-lea Seminar "Nano" 2 martie 2006
Problems and barriers in development and applications
of hydrothermal procedures for electronic materials
THREATS
Phase separation: additives for agglomeration/de-agglomeration (steric or
electrostatic effects)
Processing: fine, nanocrystalline powders require high pressures to be
compacted
special forming technologies
P
P

 
C ab
a
1
+kT
V repulsion
V total
Vt
H
-kT
V atraction
elastomer
fluid
lack of reliable and standardised characterisation methods;
anxiety of end-users vis-à-vis of environmental problems related to nanopowders
manipulation
Al 5-lea Seminar "Nano" 2 martie 2006
Center of Technological Transfer
for Advanced Materials
 Identify market requirements for new technologies, services and
products in the field of advanced biocompatible and smart metallic,
ceramic and composite materials;




Consultancy and expertise in the field of advanced materials;
Participation in elaboration of prognoses in the field;
Encouraging specialized studies for students, masters, PhD students;
Consultancy for SMEs and companies in the elaboration and
participation in national and European R&D projects;
 Support for SMEs in implementation of European standards for
materials
Al 5-lea Seminar "Nano" 2 martie 2006
Applications: hydrothermal synthesis of BST
Dielectric, piezoelectric and electro-optic properties for applications in the electronic industry: imaging
devices, optical memories, modulators, transducers, actuators, high-k dielectric constant materials.
Properties strongly dependent on the metallic elemental ratios, impurities, microstructure and grain sizes.
(1 0 1)
3000
5000
B2 P22
Ba0.77Sr0.23TiO3 44-0093
4500
4000
10
20
30
40
50
60
70
80
(2 1 1)
(2 0 0)
90
(2 2 2)
(3 0 2)
(2 1 2)
500
(3 1 1)
1500
(2 0 2)
2000
(3 1 0)
2500
1000
0
0
3000
(2 0 1)
(3 1 0)
(3 1 1)
(2 2 2)
(2 0 2)
(2 1 2)
500
(2 0 1)
(1 0 0)
1000
(2 0 0)
1500
(2 1 1)
2000
3500
(1 1 1)
Intensity [a.u]
2500
(1 1 1)
Intensity (a.u.)
B1 P27
Ba0.77Sr0.23TiO3 PDF#44-0093
(1 0 1)
5500
3500
0
20
2
30
40
50
60
70
80
90
100
2
HT synthesis 150 0C/3h; sintering 1250 0C
HT synthesis 200 0C/3h; sintering 1250 0C
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110
Applications: hydrothermal synthesis of BST
A
Non-stoichiometric; sintering 1250 0C
Stoichiometric composition
Nanodomains?
Al 5-lea Seminar "Nano" 2 martie 2006
Applications: hydrothermal synthesis of BST
BaSrTiO3_B2_P30
RT; electron beam excitation
0.25
0,16
5 ns
15 ns
0.20
Luminescence intensity
Luminescence intensity, a.u.
BaSrTiO3B2_P3
RT; e-beam excit.; no correction;
FEP100
0,18
0.15
0.10
0.05
0,14
0,12
5 ns
10. ns
20. ns
0,10
0,08
0,06
0,04
0,02
0,00
0.00
2.0
2.2
2.4
2.6
2.8
3.0
3.2
3.4
3.6
2,0
3.8
2,2
2,4
2,6
2,8
E, eV
E, eV
Cathodo-luminescence spectrum (electron beam excitation) with different delay times
BST_ ceremic
B7_P11
RT, e-beam excitation
FEP100, with correction
Luminescence intensity
0.08
0.07
FEP83
FEP100
0.06
0.05
0.04
0.03
Fundamental absorption
0.02
0.01
0.00
1.0
1.5
2.0
2.5
3.0
3.5
4.0
E, eV
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3,0
3,2
Applications: hydrothermal synthesis of BST
0.40
BST7P11
0.35
1
0.30
172
1-100 Hz
2-1000 Hz
3-10000 Hz
4-100000 Hz
5-1000000 Hz
170
168
166
2
3
B2P30
4
5
1-no
2-1000 Hz
3-10000 Hz
4-100000 Hz
5-1000000 Hz
164
0.25

tg
162
2
0.20
160
158
0.15
156
3
0.10
154
4
0.05
5
0.00
-20
0
20
40
60
80
100
120
152
150
-20
0
0
20
40
60
0
T, C
T, C
= (C*d)/(0*S)
0=8.85 810-12 farad/m,
C-capacity, farad
d-thickness, m
S-surface area, m2
Al 5-lea Seminar "Nano" 2 martie 2006
80
100
Applications: synthesis of Al-doped ZnO
•Non-stoichiometric (Zn1+xO)
•Semi-conducting transparent oxide with a large band gap (3.4eV). Doping with impurities such as Al
and In can increase the conductivity of ZnO (large values of electronic carrier density: n~1020cm-3,
and mobility: n ~ 1000 cm2V-1).
•Piezoelectric properties of zinc oxide thin films can be used in various transducers, acoustic wave
and acoustic-optical devices.
•Combination of high visible transparency and low electrical resistivity is very useful in applications
such as transparent electrodes in solar cells, luminescence display screens, ultraviolet diodes .
•When ZnO is in polycrystalline form, luminescence depends on the grain size; ZnO nanomaterials
offer from this point of view a new and promising field of investigations.
I, a.u.
4000
3000
2000
Exciton type and donor-acceptor
1000
luminescence
0
2,0
400
2,4
800
2,8
1200
t, n
s
1600
3,2
E, eV
Al 5-lea Seminar2000
"Nano" 2 martie 2006
1,6
0
Deffect associated luminescence
Applications: synthesis of Al-doped ZnO
1800
01AlZnO
41116004
Intensity [counts / sec ]
1600
1400
1200
1000
800
600
400
200
0
0
20
40
60
80
100
120
2 theta
0.1 % Al ZnO- hydrothermal precursor
1800
0,1AlZnO-vc5
41116005
Intensity [ counts / sec ]
1600
1400
1200
1000
800
600
400
200
0
0
20
40
60
80
100
120
2 theta [deg]
0.1 % Al ZnO vc5- solar furnace
R.R. Piticescu, R.M. Piticescu, C. Monty, L. Grjgorieva (under press in J.Eur.Ceram.Soc. 2006)
Al 5-lea Seminar "Nano" 2 martie 2006
Applications: synthesis of Al-doped ZnO
1000
Intensity [ counts / sec ]
0,5AlZnO
41116009
800
600
400
200
0
0
20
40
60
80
100
120
2 theta [ deg ]
0.5 Al% ZnO hydrothermal precursor
1200
Intensity [ counts / sec ]
0,5AlZnO-vc10
41116010
1000
800
600
400
200
0
0
20
40
60
80
2 theta [deg]
0.5 Al% ZnO vc10- solar furnace
Al 5-lea Seminar "Nano" 2 martie 2006
100
120
140
160
Applications: synthesis of Al-doped ZnO
Al 5-lea Seminar "Nano" 2 martie 2006
Applications: synthesis of Al-doped ZnO
[0002]
[1010]
[0002]
[1011]
[0002]
[1011]
[1010]
[1011]
[1010]
Al 5-lea Seminar "Nano" 2 martie 2006
Applications: synthesis of Al-doped ZnO
Al. contents from
chemical
analysis
[% weight]
Density
[g/cm3]
BET
[m2 / g]
Grain size
from BET
[nm]
01AlZn
41116004
Precursor
0,053
5,3932
9,3872
119
01AlZnOvc5
41116005
after SVC
0,025
5,6718
22,3151
05AlZnO
41116009
Precursor
0,45
5,3175
05AlZnOvc10
41116010
after SVC
0,15
025AlZnO
41116014
Precursor
10AlZnOvc3
41116019
after SVC
Sample
Grain size from
SEM pictures
[nm]
Grain size
from
XRD
[nm]
Morphology
Balls – dimensions
Length : 100 – 400 nm
Width : about 50 nm
[1010]- 50
[0002]- 55
[1011]- 45
Balls
57
Whiskers – dimensions
Length : about 100 nm
Thickness: about 50 nm
[1010]- 45
[0002]- 60
[1011]- 50
Whiskers
22,2015
66
Balls – dimensions
Length: 100 – 200 nm
Width: about 50 nm
[1010]- 35
[0002]- 45
[1011]- 35
Balls
5,5455
12,8577
59
Whiskers – dimensions
Length: about 200 nm
Thickness: about 50 nm
[1010]- 25
[0002]- 40
[1011]- 35
Whiskers
0,14
5,3083
17,1554
88
Plates – dimensions
Length: about 500 nm
Width: from 200 – 500 nm
Thickness: about 50 nm
[1010]- 45
[0002]- 60
[1011]- 45
Plates
0,16
4,7774
37,6204
43
Whiskers – dimensions
Length:from 200–1000 nm
Thickness: about 100 nm
[1010]- 40
[0002]- 60
[1011]- 45
Whiskers
Al 5-lea Seminar "Nano" 2 martie 2006
Applications: synthesis of Al-doped ZnO
1.5x10
0
(Bulk)
(#41116004 - 0,1%Al prekursor)
(#41116005 - 0,1%Al cienka warstwa)
0
Intensity, a.u.
Intensity, a.u.
1.0x10
5.0x10
-1
4.5x10
0
4.0x10
0
3.5x10
0
3.0x10
0
2.5x10
0
2.0x10
0
1.5x10
0
1.0x10
0
5.0x10
-1
(Bulk)
(#41116010 - 0,5%Al prekursor)
(#41116014 - 0,5%Al cienka warstwa)
0.0
0.0
350
400
450
500
550
600
650
700
750
350
400
450
500
550
600
650
700
750
Wavelength, nm
Wavelength, nm
PL spectra: two bands – band edge emission (likely of free excitonic and band-to-band and free-to-bound
origin) peaked at about 380 nm and a broad band emission (defect related band) peaking at about 520 nm to
600 nm. The broad PL band clearly is due to an overlap of two known ZnO defect related bands – ZnO red PL
emission and ZnO green PL emission. The latter dominates in samples with a higher Al fraction. Further
studies are required to get a better insight to origin of these two bands and in order to determine conditions of
their observations. We noticed that band edge emission is red shifted in nanopowders, as compared to a
spectral position of a relevant band in the reference sample.
Al 5-lea Seminar "Nano" 2 martie 2006
Applications: synthesis of Al-doped ZnO
1 0 0
% T5 0
UV-VIS spectra of 4Al
ZnO films
0
3 1 0 5 0 0
1 0 0 0
1 5 0 0
W a v e le n g th [n m
2 0 0 0
2 3 0 0
]
Pure and Al doped ZnO has been produced using the hydrothermal method. Lattice constant
increased while the density decreases with an increase of Al content. Enhancement of
luminescence with increase of Al content (related to a surface passivation or impurityrelated defect reaction?) The morphology of the product varied strongly with the synthesis
parameters.
The vaporisation-condensation technique in a solar reactor from hydrothermal precursors
lead to a change of morphology and creation of whiskers. The so-obtained
powders/whiskers show brighter light emission, even though the solubility limit of Al
decreased comparing to the precursor made using the hydrothermal method.
Al 5-lea Seminar "Nano" 2 martie 2006
CONCLUSIONS
• Hydrothermal synthesis is a versatile method for producing many nanomaterials
with controlled stoichiometry and doping elements concentrations
•Hydrothermal + electrochemical: producing of thin/thick films
•Hydrothermal + PVD : increase dopant level of elements with low vapour
pressure and control morphology
FUTURE PROSPECTS
•BST nanomaterials (sintered pellets, thin films): study the role of nanodomains
on PL spectra and electrical properties, modeling the device
•Al-ZnO nanomaterials (p-type, powders and thin films): electro-optical properties
•N-doped (n-type nanomaterials) ?
Al 5-lea Seminar "Nano" 2 martie 2006
Future prospects
Al 5-lea Seminar "Nano" 2 martie 2006
CONTACT PERSONS
 Dr.Teodor Velea, General Director
e-mail : [email protected]
 Dr. Roxana Piticescu, Lab. Head
e-mail : [email protected]
 Dr. Robert Piticescu, Director Center for Technology
Transfer in Advanced Materials
e-mail: [email protected]
 Phone/fax : 0040-21-352.20.48 / 352.20.45
 Address: 102 Biruintei Blvd., Pantelimon, judet Ilfov, Romania
Al 5-lea Seminar "Nano" 2 martie 2006
Acknowledgements
 Nanostructured Materials Group – INCDMNR Pantelimon
 Dr. C;l;aude Monty –CNRS /PROMES France
 Prof. Witold Lojkowski and Dr. Pielaszeck-UNIPRESS Warsaw
 Dr. Larisa Grjgorieva and Dr. Vismants Zaulus– Inst.
 Solid State Physics Riga
Dr. I. Sajin and Dr. M. Dragoman-Nat. Inst. Mycrotechnologies
Dr. Eugeniu Vasile – METAV CD Bucharest
dr. eng. Maria Giurginca – CNC-UPB, Bucharest
EGIDE France – supporting the ECO-Net “Fun-Nanos” project
Thank you for your attention !
Al 5-lea Seminar "Nano" 2 martie 2006