al 5-lea seminar "nano" 2 martie 2006 radu r. piticescu, roxana m. piticescu, national...

Al 5-lea Seminar "Nano" 2 martie 2006Al 5-lea Seminar "Nano" 2 martie 2006

Radu R. Piticescu,Radu R. Piticescu, Roxana M. Piticescu,Roxana M. Piticescu,

National R&D Institute for Non-Ferrous and Rare Metals, National R&D Institute for Non-Ferrous and Rare Metals,

Pantelimon, Ilfov, ROMANIAPantelimon, Ilfov, ROMANIA

IMNR


Presentation contentPresentation content

IntroductionProblems and barriers in development and

applications of hydrothermal procedures for electronic

materials Applications in BST ceramicsApplications in Al-doped ZnOConclusions and future works


Nanomaterials – the driving force, by Michael J. Pitkethly, Market Report, December 2004.

The primary of nanomaterials companies material product types and primary market focuses of nanomaterials companies

Nanomaterials market: 490 billion dollars in 2004 and 900 billion dollars in 2005 and 11 trillion dollars in 2010 (annual average grown rate > 10%)

INTRODUCTIONINTRODUCTION


INTRODUCTIONINTRODUCTION

Hydrothermal reactions: chemical processes at high pressures and temperatures over the boiling temperature in aqueous solutionsSolvothermal reactions: chemical processes at high pressures and temperatures in non-aqueous solutions

Hydrothermal reactions between species in hydrothermal solutionsHydrothermal reactions between species in hydrothermal solutions One elementM(II)2+(aq) + 2OH-(aq) = MO+H2O; M(II)=alcaline-earth metals: Mg, Ca, Sr, Ba2M(III)3+(aq) + 6OH-(aq) = M2 O3 + 3H2O; M(III)= Al, Ga, LnM(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 transformation of amorphous species in crystalline ones (under the influence of temperature and pressure): ones (under the influence of temperature and pressure):

M(OH)n = MOn/2 +(n/2) H2OM(OH)n = MOn/2 +(n/2) H2O


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



STRENGTHS OF HYDROTHERMAL SYNTHESISAny shape, any size (combining with other external driving forces, e.g. electrochemical)

U/I

Cathode

Reference Anode 0

100

200

300

400

500 0

20

40

60

80

100

120 PT; PZ; ST; BT

Electrophoretic deposition

Hydrothermal deposition

PT; PZ; ST; BT

R.R. Piticescu, R.M. Piticescu, Workshop COST D30, Turin, 26-28 Feb. 2004



WEAKNESSES

• Prediction: Lack of thermodynamic data (only for ideal solutions, low valence ions)

Ji is the stoechiometric coefficient of species “i” in the reaction “j”

G0f is the standard free enthalpy of formation of reacting species AJ

i

mAi is the molar concentration of species Ai the solution

i is the activity coefficient

qH])OH()OH(M[])OH(M[m )qmz(qqmn2

p,Tzn

nJ

1i

Ji

0f

Jij )A(GKlnRT

nJ

i

JiAiAiJ mK

1

,)( log Ai = Hi +BZi + Pi

Lencka and Riman (Rutgers Univ), J.Am.Ceram.Soc, 76, 10, 2649-59 (1993)



WEAKNESSES

• Prediction: Kinetic limitations

0 5000 1 104

1.5 104

0

50

70

0

Fc t( )

150000 t

125C

ft

t

0 5000 1 104

1.5 104

0

50

100100

0

Fc t( )

150000 t

150C

)1(2)1(31 3/2 ft

t

R.R. Piticescu, C. Monty, D. Taloi, D. Millers, Sensor and Actuators B, 109 (1), 102-6 (2005)

0

10

20

30

40

50

0 2 4 6 8 10

Time (h)

D (n

m)

-ln (1-)= kt m

Roxana M. Piticescu, R. R. Piticescu, D.Taloi, V. Badilita, Nanotechnology vol. 14 (3), pp. 312-17 (2003)

0 5000 1 104

1.5 104

0

50

100100

0

Fc t( )

150000 t

200C

3/1)1(1 ft

t



OPPORTUNITIES

VERSATILITY:Oxides, non-oxides, organic/biologic materials; hybrid materialsHYDROTHERMAL 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).


Nucleation and growth-surface diffusion- continuous growth at the kinks

)(022adc c

j

Fz

RT

dt

d

-Formation of clusters and critical nuclei- Formation of monolayrers by layer to layer growth

W(t) = W0 ( 1 - ekt )

Types of morphologies

-Layer or platelate growth- Pyramidal growth-Whiskeres-Dendrites-Epitaxial growth on crystalline substrates-Oriented growth on polycrystalline or amoprphous substrates

Unpredictible!




Vt

+kT

-kT

H

V repulsion

V atraction

V total

THREATSPhase separation: additives for agglomeration/de-agglomeration (steric or electrostatic effects) Processing: fine, nanocrystalline powders require high pressures to be compacted special forming technologies

lack of reliable and standardised characterisation methods;

anxiety of end-users vis-à-vis of environmental problems related to nanopowders manipulation

fluidelastomer

PC ab

P

a

1


Center of Technological Transfer Center of Technological Transfer

for Advanced Materialsfor Advanced Materials

Identify market requirements for new technologies, services and Identify market requirements for new technologies, services and

products in the field of advanced biocompatible and smart metallic, products in the field of advanced biocompatible and smart metallic,

ceramic and composite materials;ceramic and composite materials;

Consultancy and expertise in the field of advanced materials;Consultancy and expertise in the field of advanced materials;

Participation in elaboration of prognoses in the field;Participation in elaboration of prognoses in the field;

Encouraging specialized studies for students, masters, PhD students;Encouraging specialized studies for students, masters, PhD students;

Consultancy for SMEs and companies in the elaboration and Consultancy for SMEs and companies in the elaboration and

participation in national and European R&D projects;participation in national and European R&D projects;

Support for SMEs in implementation of European standards for Support for SMEs in implementation of European standards for

materialsmaterials


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.

0 10 20 30 40 50 60 70 80 900

500

1000

1500

2000

2500

3000

3500

(2 2

2)

(3 1

1)

(3 1

0)

(2 1

2)(2 0

2)(2

1 1

)(2

0 1

)

(2 0

0)

(1 1

1)

(1 0

1)

(1 0

0)

Inte

nsity

(a.u

.)

2

B1 P27 Ba

0.77Sr

0.23TiO

3 PDF#44-0093

HT synthesis 150 0C/3h; sintering 1250 0C

20 30 40 50 60 70 80 90 100 1100

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

5500

(3 0

2)(2 2

2)

(3 1

1)

(3 1

0)

(2 1

2)

(2 0

2)

(2 1

1)

(2 0

1)

(2 0

0)

(1 1

1)

(1 0

1)

B2 P22 Ba

0.77Sr

0.23TiO

3 44-0093

Inte

nsi

ty [

a.u

]2

HT synthesis 200 0C/3h; sintering 1250 0C



A

Non-stoichiometric; sintering 1250 0C Stoichiometric composition

Nanodomains?



2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4 3.6 3.80.00

0.05

0.10

0.15

0.20

0.25

BaSrTiO3_B2_P30

RT; electron beam excitation

Lum

ines

cenc

e in

tens

ity, a

.u.

E, eV

5 ns 15 ns

2,0 2,2 2,4 2,6 2,8 3,0 3,20,00

0,02

0,04

0,06

0,08

0,10

0,12

0,14

0,16

0,18 BaSrTiO3B2_P3

RT; e-beam excit.; no correction;FEP100

Lu

min

esc

en

ce in

ten

sity

E, eV

5 ns 10. ns 20. ns

Cathodo-luminescence spectrum (electron beam excitation) with different delay times

1.0 1.5 2.0 2.5 3.0 3.5 4.00.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08 BST_ ceremicB7_P11RT, e-beam excitationFEP100, with correction

Lu

min

esc

en

ce in

ten

sity

E, eV

FEP83 FEP100

Fundamental absorption



-20 0 20 40 60 80 100 1200.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40 1-100 Hz2-1000 Hz3-10000 Hz4-100000 Hz5-1000000 Hz

54

3

2

1

tg

T, 0C

BST7P11

-20 0 20 40 60 80 100150

152

154

156

158

160

162

164

166

168

170

1722

34

5 1-no2-1000 Hz3-10000 Hz4-100000 Hz5-1000000 Hz

T, 0C

B2P30

= (C*d)/(0*S)0=8.85 810-12 farad/m,C-capacity, faradd-thickness, mS-surface area, m2


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.

1,62,0

2,4

2,8

3,2

0400

8001200

1600

2000

0

1000

2000

3000

4000

I, a.u.

E, eV

Exciton type and donor-acceptor

luminescence

Deffect associated luminescence



0 20 40 60 80 100 1200

200

400

600

800

1000

1200

1400

1600

1800

Inte

nsi

ty [

cou

nts

/ se

c ]

2 theta

01AlZnO 41116004

0.1 % Al ZnO- hydrothermal precursor

0 20 40 60 80 100 1200

200

400

600

800

1000

1200

1400

1600

1800

Inte

nsi

ty [

co

un

ts /

sec

]

2 theta [deg]

0,1AlZnO-vc5 41116005

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)



0 20 40 60 80 100 1200

200

400

600

800

1000

Inte

nsit

y [

co

un

ts / s

ec ]

2 theta [ deg ]

0,5AlZnO 41116009

0.5 Al% ZnO hydrothermal precursor

0 20 40 60 80 100 120 140 1600

200

400

600

800

1000

1200

Inte

nsit

y [

co

un

ts / s

ec ]

2 theta [deg]

0,5AlZnO-vc10 41116010

0.5 Al% ZnO vc10- solar furnace



[0002]

[1010]

[1011]

[0002]

[1011]

[1010]

[0002]

[1011]

[1010]



Sample Al. contents from chemical analysis

[% weight]

Density[g/cm3]

BET [m2 / g]

Grain size from BET

[nm]

Grain size from SEM pictures

[nm]

Grain size from XRD [nm]

Morphology

01AlZn41116004Precursor

0,053 5,3932 9,3872 119 Balls – dimensionsLength : 100 – 400 nmWidth : about 50 nm

[1010]- 50[0002]- 55[1011]- 45

Balls

01AlZnOvc541116005after SVC

0,025 5,6718 22,3151 57 Whiskers – dimensionsLength : about 100 nmThickness: about 50 nm

[1010]- 45[0002]- 60[1011]- 50

Whiskers

05AlZnO41116009Precursor

0,45 5,3175 22,2015 66 Balls – dimensionsLength: 100 – 200 nmWidth: about 50 nm

[1010]- 35[0002]- 45[1011]- 35

Balls


0,15 5,5455 12,8577 59 Whiskers – dimensionsLength: about 200 nmThickness: about 50 nm

[1010]- 25[0002]- 40[1011]- 35

Whiskers

025AlZnO41116014Precursor

0,14 5,3083 17,1554 88 Plates – dimensionsLength: about 500 nmWidth: from 200 – 500 nmThickness: about 50 nm

[1010]- 45[0002]- 60[1011]- 45

Plates


0,16 4,7774 37,6204 43 Whiskers – dimensionsLength:from 200–1000 nmThickness: about 100 nm

[1010]- 40[0002]- 60[1011]- 45

Whiskers



350 400 450 500 550 600 650 700 7500.0

5.0x10-1

1.0x100

1.5x100

Inte

nsity, a

.u.

Wavelength, nm

(Bulk) (#41116004 - 0,1% Al prekursor) (#41116005 - 0,1% Al cienka warstwa)

350 400 450 500 550 600 650 700 7500.0

5.0x10-1

1.0x100

1.5x100

2.0x100

2.5x100

3.0x100

3.5x100

4.0x100

4.5x100

Inte

nsity, a

.u.

Wavelength, nm

(Bulk) (#41116010 - 0,5% Al prekursor) (#41116014 - 0,5% Al cienka warstwa)

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.



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 impurity-related 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.

0

100

50

310 2300500 1000 1500 2000

%T

Wavelength[nm]

UV-VIS spectra of 4Al ZnO films


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) ?


Future prospects


CONTACT PERSONS CONTACT PERSONS

Dr.Teodor Velea, General Director Dr.Teodor Velea, General Director

e-mail : e-mail : [email protected]@imnr.ro Dr. Roxana Piticescu, Lab. Dr. Roxana Piticescu, Lab. HeadHead

e-mail : e-mail : [email protected]@imnr.ro Dr. Robert Piticescu, Director Center for Technology Dr. Robert Piticescu, Director Center for Technology

Transfer in Advanced MaterialsTransfer in Advanced Materials

e-mail: [email protected]: [email protected] Phone/fax : 0040-21-352.20.48 / 352.20.45 Phone/fax : 0040-21-352.20.48 / 352.20.45 Address: 102 Biruintei Blvd., Pantelimon, judet Ilfov, RomaniaAddress: 102 Biruintei Blvd., Pantelimon, judet Ilfov, Romania


AcknowledgementsAcknowledgementsAcknowledgementsAcknowledgements

Thank you for your attention !

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

al 5-lea seminar "nano" 2 martie 2006 radu r. piticescu, roxana m. piticescu, national...

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