1. Al 5-lea Seminar "Nano" 2 martie 2006 Radu R. Piticescu, Roxana M. Piticescu, National R&D Institute for Non-Ferrous and Rare Metals, Pantelimon, Ilfov, ROMANIA IMNR

2. 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

3. Al 5-lea Seminar "Nano" 2 martie 2006 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%)INTRODUCTION

4. 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 non- aqueous 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 : transformation of amorphous species in crystalline ones (under the influence of temperature and pressure): Hydrothermal crystallisation: transformation of amorphous species in crystalline ones (under the influence of temperature and pressure): M(OH)n = MOn/2 +(n/2) H2O

5. 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

6. 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 Cathode ReferenceAnode 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

7. 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) J i is the stoechiometric coefficient of species i in the reaction j G 0 f is the standard free enthalpy of formation of reacting species A J i m Ai is the molar concentration of species A i the solution i is the activity coefficient log Ai = H i +BZ i + P i Lencka and Riman (Rutgers Univ), J.Am.Ceram.Soc, 76, 10, 2649-59 (1993)

8. Al 5-lea Seminar "Nano" 2 martie 2006 Problems and barriers in development and applications of hydrothermal procedures for electronic materials WEAKNESSES Prediction: Kinetic limitations 125C 150C R.R. Piticescu, C. Monty, D. Taloi, D. Millers, Sensor and Actuators B, 109 (1), 102-6 (2005) -ln (1- )= kt m Roxana M. Piticescu, R. R. Piticescu, D.Taloi, V. Badilita, Nanotechnology vol. 14 (3), pp. 312-17 (2003) 200C

9. 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][2][3][5] [1][1] Solozhenko,V. L., Dub, S. N. & Novikov, N. Diamond Relat.Mater. 10, 2228–2231 (2001) [2][2] Taniguchi, T. et al. Jpn. J.Appl. Phys. 241, L109–L111 (2002). [3][3] I.A.Presniakov, G.Demazeau, A.V.Baranov, A.V.Sobolev, K.V.Pokholok., Phys. Rev. B71, 2005, 054409I.A.Presniakov, G.Demazeau, A.V.Baranov, A.V.Sobolev, K.V.Pokholok., Phys. Rev. B71, 2005, 054409 [4][4] Gryko, J. et al. Phys. Rev. B 62, 7707–7710 (2000). [5][5] Ishiwata S, Azuma M, Takano M, et al, J. Mater. Chem. 12, 3733 (2002).

10. Al 5-lea Seminar "Nano" 2 martie 2006 Nucleation and growth -surface diffusion - continuous growth at the kinks -Formation of clusters and critical nuclei - Formation of monolayrers by layer to layer growth W(t) = W0 ( 1 - e kt ) Types of morphologies -Layer or platelate growth - Pyramidal growth -Whiskeres -Dendrites -Epitaxial growth on crystalline substrates -Oriented growth on polycrystalline or amoprphous substrates Unpredictible! Problems and barriers in development and applications of hydrothermal procedures for electronic materials

11. Al 5-lea Seminar "Nano" 2 martie 2006 Problems and barriers in development and applications of hydrothermal procedures for electronic materials V t +kT -kT H V repulsion V atraction V total 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 lack of reliable and standardised characterisation methods; anxiety of end-users vis-à-vis of environmental problems related to nanopowders manipulation fluid elastomer

12. 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; 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; 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 participation in national and European R&D projects; 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 Support for SMEs in implementation of European standards for materials

13. 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. HT synthesis 150 0 C/3h; sintering 1250 0 CHT synthesis 200 0 C/3h; sintering 1250 0 C

14. Al 5-lea Seminar "Nano" 2 martie 2006 Applications: hydrothermal synthesis of BST A Non-stoichiometric; sintering 1250 0 CStoichiometric composition Nanodomains?

15. Al 5-lea Seminar "Nano" 2 martie 2006 Applications: hydrothermal synthesis of BST Cathodo-luminescence spectrum (electron beam excitation) with different delay times Fundamental absorption

16. Al 5-lea Seminar "Nano" 2 martie 2006 Applications: hydrothermal synthesis of BST = (C*d)/( 0 *S) 0 =8.85 810 -12 farad/m, C-capacity, farad d-thickness, m S-surface area, m 2

17. Al 5-lea Seminar "Nano" 2 martie 2006 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. Exciton type and donor-acceptor luminescence Deffect associated luminescence

18. Al 5-lea Seminar "Nano" 2 martie 2006 Applications: synthesis of Al-doped ZnO 0.1 % Al ZnO- hydrothermal precursor 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)

19. Al 5-lea Seminar "Nano" 2 martie 2006 Applications: synthesis of Al-doped ZnO 0.5 Al% ZnO hydrothermal precursor 0.5 Al% ZnO vc10- solar furnace

20. Al 5-lea Seminar "Nano" 2 martie 2006 Applications: synthesis of Al-doped ZnO

21. Al 5-lea Seminar "Nano" 2 martie 2006 Applications: synthesis of Al-doped ZnO [0002] [1010] [1011] [0002] [1011] [1010] [0002] [1011] [1010]

22. Al 5-lea Seminar "Nano" 2 martie 2006 Applications: synthesis of Al-doped ZnO SampleAl. contents from chemical analysis [% weight] Density [g/cm 3 ] BET [m 2 / g] Grain size from BET [nm] Grain size from SEM pictures [nm] Grain size from XRD [nm] Morphology 01AlZn 41116004 Precursor 0,0535,39329,3872119Balls – dimensions Length : 100 – 400 nm Width : about 50 nm [1010]- 50 [0002]- 55 [1011]- 45 Balls 01AlZnOvc5 41116005 after SVC 0,0255,671822,315157Whiskers – dimensions Length : about 100 nm Thickness: about 50 nm [1010]- 45 [0002]- 60 [1011]- 50 Whiskers 05AlZnO 41116009 Precursor 0,455,317522,201566Balls – dimensions Length: 100 – 200 nm Width: about 50 nm [1010]- 35 [0002]- 45 [1011]- 35 Balls 05AlZnOvc10 41116010 after SVC 0,155,545512,857759Whiskers – dimensions Length: about 200 nm Thickness: about 50 nm [1010]- 25 [0002]- 40 [1011]- 35 Whiskers 025AlZnO 41116014 Precursor 0,145,308317,155488Plates – dimensions Length: about 500 nm Width: from 200 – 500 nm Thickness: about 50 nm [1010]- 45 [0002]- 60 [1011]- 45 Plates 10AlZnOvc3 41116019 after SVC 0,164,777437,620443Whiskers – dimensions Length:from 200–1000 nm Thickness: about 100 nm [1010]- 40 [0002]- 60 [1011]- 45 Whiskers

23. Al 5-lea Seminar "Nano" 2 martie 2006 Applications: synthesis of Al-doped ZnO 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.

24. Al 5-lea Seminar "Nano" 2 martie 2006 Applications: synthesis of Al-doped ZnO 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. UV-VIS spectra of 4Al ZnO films

25. 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) ?

26. Al 5-lea Seminar "Nano" 2 martie 2006 Future prospects

27. Al 5-lea Seminar "Nano" 2 martie 2006 CONTACT PERSONS Dr.Teodor Velea, General Director Dr.Teodor Velea, General Director e-mail : tvelea@imnr.ro tvelea@imnr.ro Dr. Roxana Piticescu, Lab. Head Dr. Roxana Piticescu, Lab. Head e-mail : roxana@imnr.ro roxana@imnr.ro Dr. Robert Piticescu, Director Center for Technology Transfer in Advanced Materials Dr. Robert Piticescu, Director Center for Technology Transfer in Advanced Materials e-mail: rpiticescu@imnr.ro 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, Romania Address: 102 Biruintei Blvd., Pantelimon, judet Ilfov, Romania

28. Al 5-lea Seminar "Nano" 2 martie 2006 AcknowledgementsAcknowledgements 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