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Nanomaterials for solar energy conversion and storage
Members: Thomas Cottineau, Chia Erh Liu, Mireille Richard, Hélène Terrisse, Luc Brohan, Boryana Todorova, Thomas Beuvier, Aurelian Popa

Summary:
Aims :

The aim of the /OxTi-MiB /project is to provide technological breakthroughs in the field of both conversion and storage of solar energy by the development of a IIIrd generation solar cell (metallic intermediate band (MIB)) with high conversion efficiency and a rechargeable photobattery. *These devices are *required to be efficient, inexpensive, environmentally friendly and in agreement with the sustainable development. The /OxTi-MiB/ pluridisciplinary project involves French scientists: experimental chemists (IMN/CESES, Nantes) and physicists (LPEC, Le Mans; GMCM, Rennes), chemical theorists (CTMM, Montpellier), interface specialists (LACE, Toulouse), in thin films (IMN/LPCM, Nantes), in photovoltaics (POMA, Angers) and also industrial partners.

Results :

From the polycondensation of titanium oxides… to the setting-up of a photobattery!

 

Due to the potential applications in the field of environmental protection,the photochemistry of TiO2 is a fast growing area both in terms of research and commercial activity[1].Over the past decade, the level of research activity concerning TiO2 can be appreciated through the exponential increase of relevant research literature produced [2][3][4 (11 500 publications between 1993 and 2003) and the number of patents regarding, for instance, photocatalysis (3000 between 1996 and 2001, and more recently 2500 in Japan and 500 in USA). These features account for the intense fundamental research activity involving the scientific community. This particular interest is related to the remarkable photoactive properties of TiO2 and therefore to its numerous applications, which are related to two main environmental priorities: environmental protection through heterogeneous catalysis (water purification, air cleaning, self cleaning materials), and renewable energy production in photoelectrochemical solar cells, dye sensitised solar cells (DSSC1). In addition to this high added value, titanium dioxide is non toxic and biocompatible and therefore it is also used as a coating layer in bone reconstruction surgery but also in the cosmetic industry and as a white mineral charge in painting.

1 A low cost, high efficiency solar cell based on dye-sensitized colloidal TiO2 films” B. O’Regan and M. Grätzel, Nature, 353, (1991).

Our activity, in the field of titanium oxides obtained by chimie douce, relies on sound and long term knowledge. Some highlights deserve to be mentioned:

- Identification of two original varieties of titanium dioxides: TiO2(B), (L. Brohan’s Ph.D, 1986) TiO2(H) (M. Latroche’s Ph.D 1989)

- Characterisation of several metastable titanates. Their optical and photocatalytical properties were studied by M. Richard (Ph.D, 1994)

- Interpretation and modelling of the TiO2(B) to anatase transformation and the transition from 2D to 3D titanates.

- Evidence of order-disorder transitions associated to a charge density wave in titanium bronzes (D. Brunet’s Ph.D, 1994)

- Origin of fatigue in ferroelectric materials (Bi4-xLaxTi3O12) (M. W. Chu’s Ph.D, 2002)

In a « Bottom up » approach, work performed in our group (IMN, UMR 6502, Nantes M. Mancini-Le Granvalet’s Ph.D (1994), H. Sustrisno’s Ph.D (2001), A. Rouet’s Ph.D (2005)) has shown that it is not only possible to control the cristalline structure, the morphology and crystal size of the three TiO2 varieties, anatase, brookite and rutile but we are also able to obtain new varieties of nano-meso-structured titanium oxo-hydroxides. Their crystalline structures only differ by the way the octahedral are connected either by sharing edges and/or corners. Their nanometric dimensions provide them original optical and redox properties. Here are reported recent results concerning these new photosensitive nanomaterials and their potential advantages in highly efficient photoelectrochemical cells and photobatteries.

References

[1]    A. Mills, S.-K. Lee, Journal of Photochemistry and Photobiology A: Chemistry 152 (2002) 233–247

[2] D. M. Blake, NREL/TP-570-26797 (1999) Report ; www.osti.gov/bridge

[3]    Ulrike  Dielbold, “The surface science of titanium dioxide”, Surface Science Reports 48 (2003) 53-229.

[4]    H.A. Al-Abadleh, V.H. Grassian / Surface Science Reports 52 (2003) 63–161

 

 

From the polycondensation of titanium oxides…

Fig. 1: structure of the [Ti8O12(H2O)24]8+ octamer.

 

- Structural originality of titanium oxo-hydroxide sols and gels:

The structure of ([Ti8O12(H2O)24]Cl8•HCl•7H2O), is built of octameric polycations, Ti8O12(H2O)248+, connected to each other through hydrogen bonds. Each octameric unit derives from ReO3 structure and presents a pseudo-cubic symmetry (Fig.1). The cluster is formed by association of eight TiO3(H2O)3 distorted octahedra, sharing three of their corners. This 0D octamer can be used as a new interesting precursor of titanium dioxide because totally inorganic, soluble in polar solvents, it is easily handled. Its hydrolysis in aqueous medium and in soft thermal conditions (T<120°C) leads to the synthesis of different titanium oxides or titanates, depending on the R = Ti/OH ratio, with various dimensionalities, morphologies and preferential orientations.

 

Progress in the field of photocatalysis mainly depends on our ability to understand fundamental details concerning the correlation between chemical reactivity, during photocatalysis and the face orientation of crystals which are formed during nucleation-growth of TiO2. Improvement of photocatalytic properties requires us to control not only the allotropic variety of TiO2 and dimensionality of Ti-O framework: 0D, 1D, 2D or 3D but also self-assembling of the deposition and its adhesion to the appropriate substrate. A fine control of the different synthesis steps is necessary in order to reach the stage leading to titanium oxide nanoparticles with the required crystalline structure, defined shapes and sizes and even the most suitable crystallographic planes for a given application. These objectives imply better knowledge of polycondensation processes and physicochemistry of particle surface of the precursor in suspension.

Therefore, we recently studied the processes involved during polycondensation while hydrolysis of titanium salts takes place. We demonstrated that a control of polycondensation, at temperatures ranging from 25 °C to 120 °C, may allow the formation of sols, gels or solids with well defined framework dimensionality: 0D island or dots, 1D wires, 2D layers or 3D frameworks and even nanotubes. More precisely, a prominent role seems to be attributed to various parameters such as reactant concentration, solvent, ionic force of the solution, poly-ions charge and chemical nature of counter-ions, temperature or pH. All these parameters may influence the way the Ti-O framework is built in the material. The charge density by area unit and the volume fraction of species are also determinant factors concerning dimensionality and then self-organisation of materials (IMN, N. Fossé’s Ph.D 1998 ; T. Drezen’s Ph.D 1998).

In the case of hydrolysis and condensation is conducted in non aqueous solvent, XAS coupled to TEM analysis (Fig. 2 and 3) reveal that the so-obtained sols and gels present polymeric structures which may differ depending on the nature of titanium precursor but are formed by octahedra sharing edges and corners.

These preliminary encouraging results suggest that it is possible to finely tune the polycondensation advancement and also to favour crystallographic planes to the detriment of others.

Fig. 3 : Deposition of gel on glass slide, with control of adhesion and thickness. .

 

 

Fig. 2  : Polymeric structure of gel, spacing between fibres is 0.4 nm.

… to the setting-up of a photobattery !

- Original optoelectronic properties of titanium oxo-hydroxide sols and gels :

In comparison with bulk, sols and gels including semiconducting nanoparticles in strong interaction with solvent, exhibit unusual optical and electronic properties. The latter are related to charge transfer occurring at the interface between the semiconductor and the liquid. These semiconducting sols and gels present a high density of active sites because of their large surface/volume ratio due to their structuration at the nanometre level. Then, the surface states play a prominent role in the electronic structure. This particular situation may theoretically increase the efficiency of photoelectrochemical solar cells.

 

In oxidising conditions, the polymeric sols are photosensitive: originally transparent without illumination, they turn to yellow, and then to orange or red depending on the Ti concentration. From our first results we conclude that this coloration could be attributable to the formation of peroxo (O2)2- species. The intensity of absorbance depends on illumination time, on thermal treatment conditions, on partial pressure in oxygen above the sol and also on titanium concentration.

Increasing the illumination time means sols and gels change to a dark blue colour associated to reduction of Ti(IV) to Ti(III). This phenomenon induces a large absorption band in the visible range which extends to the IR domain (fig. 4). After air exposure, the gel becomes transparent again and may again be coloured under illumination. The reversible colour changing is associated to the charge and discharge of electrons in the nanomaterial (Fig. 5). Therefore we infer that new electronic devices, namely photobatteries, may be developed in which solar energy would be converted and stored.

Fig. 4: Absorption ranges of organic-inorganic Ti-O based sol and gel.

Fig. 5  : Influence of illumination of gel and reversibility phenomenon.

The rechargeable photobattery is a new solar device with two functions: opto-electrical conversion and storage as electrochemical energy. One advantage of such a set-up is to store solar energy without external batteries and control circuits.

As we could obtain new photosensitive nanomaterials based on titanium oxide, with original structural and optoelectronic properties (8 national and international patents since 2002) we are able to study in situ and at the atomic scale, the heterogeneities of surface and the oxydo-reduction phenomenon, that are formed under illumination.

Understanding the quantum-sized properties of these new photosensitive sols and gels requires not only a multidisciplinary approach but also the implementation of numerous characterisation techniques. In particular, we aimed to develop tools devoted to the study of the chemical nature of interface and the energetic nature of surface states. These tools would allow us to understand how the structure governs the energy transfers and losses. XAS, EPR, XPS, zetametry, photocorrelation and femto-second spectroscopies are particularly suitable for in situ and ex situ characterisation of our nanomaterials in their different shaping: from sol to gel, then to film and finally to device.

Research directions :

Optimising the conversion of solar energy to chemical energy certainly requires understanding photocatalytic phenomena at interfaces. If most authors agree that the catalysor takes part in the processes of photodegradation of organics, because atoms of its surface are incorporated in the products (19), then major improvements are still necessary. Among them, the main locking lye in understanding photochemical phenomena, precising the chemical and electronic nature of surface states and lastly identifying the structure of active sites.

 Our research orientations are divided into four axes :

-To gain a better understanding of emerging physical phenomena and in particular physicochemistry of oxide/electrolyte interfaces and interaction between oxide and UV light. In our photosensitive sols and gels, titanium oxide nanoparticles present a large surface/volume ratio and therefore we have the opportunity to study in situ structural and electronic modifications induced by illumination at the oxide/electrolyte interface.

- To exploit new physical phenomena associated to semiconducting particles with quantum size dimension and finalise original synthesis and deposition methods suitable for sol-gel technology.

- To implement analytical tools and theoretical methods aiming to understand photoelectrochemical processes and photocatalytical chemical reactions. Most of the theoretical tools undertaken in this project imply new fundamental approaches that will be validated by experimental proofs. Thus the image given by modelling these oxides and the oxide/electrolyte interface, at microscopic level, will allow us to correlate the effect of illumination to any change of their structural and electronic properties.

- To set up devices and optimise their performances in order to significantly overcome present limits.

(19)The surface science of titanium dioxide, Ulrike Diebold, Surface Science Reports 48, 53-229, (2003).

Expected scientific and technological spin off  :

Understanding the physicochemistry of interface between oxide and electrolyte and interaction between oxide and UV light in titanium oxides is expected to benefit several fields. Our conclusions will naturally lead to applications regarding two major environmental problems: renewable energy (highly efficient photovoltaic, photobattery, water photosplitting) and pollution (photocalysis: water treatment, depollution and purification of air, self-cleaning glasses, protection of buildings…). These conclusions will also be extended to other domains such as: photoelectrochromism, paintings, resin coating…these applications cover wide markets and the huge interest of industrials is reflected in the evolution of the number of patents regarding the applications of TiO2 in the field of photo-oxidation catalysis (PCO) or photo-superhydrophobicity (PSH).  

Collaborations
  • J. M. Nunzi, E-mail :jean-michel.nunzi@univ-angers.fr, POMA, ERT Photovoltaïque,
    2, Bd. Lavoisier, 49045 Angers,
  • A. Gibaud, E-mail : Gibaud@univ-lemans.fr, UMR 6087 CNRS, Laboratoire de Physique de l’Etat condensé, Faculté des Sciences, Bd O. Messiaen, 72085 Le Mans Cedex 0
  • M. L. Doublet, E-mail :Marie-Liesse.Doublet@univ-montp2.fr ,CNRS - UMR 5253, Chimie Théorique Méthodologies Modélisations, (CTMM) , Université Montpellier II , Place Eugène Bataillon, 34 095   Montpellier Cedex 5,
  • E. Puzenat, E-mail :Eric.puzenat@univ-lyon1.fr, UMR-CNRS 5643, Laboratoire d’Application de la Chimie à l’Environnement (LACE), Université Claude Bernard Lyon1,  43 Boulevard du 11 Novembre 1918, 69622 Villeurbanne Cedex,
  • M. Lorenc , E-mail :maciej.lorenc@univ-rennes1.fr, CNRS - UMR 6626, Groupe Matière Condensée et Matériaux (GMCM) 35042 Rennes ,
  • F. Villain, Laboratoire pour l’Utilisation du Rayonnement, Electromagnétique (LURE), Centre Universitaire Paris-Sud, BP34, 91898 Orsay Cedex,
  • C. Alonso, E-mail: corinne.alonso@laas.fr, Laboratoire d’Analyse et d’Architecture des Systemes, (LAAS) - CNRS - UPR 8001,
    31077 Toulouse,
  • Vermeersch M. Total, Direction Energies Renouvelables, 2, Place de la Coupole – La Défense 6, 92078 Paris La Défense CEDEX,
  • Benabdelkarim M. Vaillant Group Program Manager Saunier Duval Eau Chaude Chauffage Industrie, 17 rue de la petite baratte BP 41535 , 44315 Nantes Cedex 03
Patents
  1. Propriétés photovoltaïques d’un thiospinel dopé au sodium.
    Brevet Français numéro 01.09020 en date du 6 juillet 2001
    N. Barreau, J. C. Bernede, C. Deudon, L. Brohan.
  2. Polymère sol-gel à base de TiO2, Brevet Français CNRS priorité N° 0201055 (29/01/2002)
    L. Brohan, H. Sutrisno, Y. Piffard, M. Caldes, O. Joubert.
  3. Polymère sol-gel à base d’oxyde de titane
    L. Brohan, H. Sutrisno, Y. Piffard, M. Caldes, O. Joubert, E. Puzenat, A. Rouet.
    Demande internationale du 14.01.2003 n° PCT/FR03/00106
    - Publication Internationale N° WO 03/064324 A3 (07/08/2003).
    - Européen (EP) n° 03 734 737.4 du 14.01.2003
    Pays couverts: Allemagne, Autriche, Belgique, Bulgarie, Chypre, Danemark,  Espagne, Estonie, Grèce, Hongrie, Finlande, France, Gde Bretagne, Irlande, Luxembourg, Monaco, Pays-bas, Portugal, République Tchèque, Slovaquie, Slovénie, Suède, Suisse,/Liechtenstein, Turquie.
    - Etats-Unis (US) n° non encore attribué
    - Japon (JP) n° 2003-563956 en date du 03/08/2004
  4. Aquo-oxo chlorure de titane, procédé pour sa préparation. Brevet Français CNRS priorité N° 0305619 (09/05/2003). L. Brohan, H. Sutrisno, E. Puzenat, A. Rouet, H. Terrisse.
  5. Titanium aquo-oxochloride and preparation method thereof.
    L. Brohan, H. Sutrisno, E. Puzenat, A. Rouet., H. Terrisse.
    Demande internationale du 29/04/2004 CNRS patent PCT/FR04/01038.
    - Publication internationale n° WO 2004/101436 A2 en date du 25/11/2004.
    - Européen (EP) n° 04 742 604.4 (29/04/2004).
    Pays couverts: Allemagne, Autriche, Belgique, Bulgarie, Chypre, Danemark,  Espagne, Estonie, Grèce, Hongrie, Finlande, France, Gde Bretagne, Irlande, Luxembourg, Monaco, Pays-bas, Portugal, République Tchèque, Slovaquie, Slovénie, Suède, Suisse,/Liechtenstein, Turquie.
    - Etats-Unis (US) (en cours)
    - Japon (JP) (en cours).
Theses
  1. Synthèse et caractérisation d’oxydes de titane (TiO2) micro-mésostructurés à dimensionalité controlée, (0D, 1D , 2D, 3D).
    Hari SUTRISNO – 24 octobre 2001. (SFERE)
  2. De la polycondensation des oxydes de titane à la génération d’une photobatterie.
    Annabelle Rouet – 19 septembre 2005. (Bourse de thèse co-financée IMN-Région)
  3. Oxydes de titane nanostructurés : nanofils, nanotubes, nanofeuillets.
    Ming Wen Peng (juin 2006) (Collaboration Taïwan)
  4. Propriétés photoélectrochimiques de polymères oxygénés du titane
    Thomas Cottineau (Juin 2007). (Allocation de recherche BDI CNRS-Région).
  5. De la nanostructuration des oxydes de titane.
    Chia Erh Liu (Juin 2008) (Absence de financement)
Contracts - Distinction

- Action Concertée Incitative Energie (2003-2004): « Nanopolymères oxygénés du titane pour cellules Photovoltaïques et développement de Photobatteries » (Coordinateur : L. Brohan).

- Contrat plan état-région (2000-2006) CER-M4 intitulé « matériaux à propriétés électroniques spécifiques  dont l’objectif consiste à renforcer l’activité Nanomatériaux-Nanotechnologies à l’Institut des Matériaux de Nantes (Coordinateur : S. Lefrant).

- Action Concertée Incitative Nano (Juin 2004 – Juin 2007) Ox-Ti Photobatterie (Coordinateur : L. Brohan).
DGA, Ministère de la recherche : N° du projet : NR043

- Projet ANR-06-PSPV-015 (2006-2009) Titre : OxTiMIB (Coordinateur L. Brohan),

- Projet PERLE (Pole Emergent de Recherche Ligérienne en Energie) (Coordinateurs : G. Ouvrard, C. Castelain),

- BDI CNRS-Région 2004-2007: thèse T. Cottineau ,

- Total, Energies Renouvelables : BDI Total-CNRS 2006-2009: thèse T. Beuvier

- Vaillant Group (Saunier-Duval) CIFRE 2006-2009: thèse Boryana Todorova.

1er Prix dans la catégorie Environnement des 12èmes Carrefours de la Fondation Rhône−Alpes Futur,(Lyon) (2005).

 

Publications
  1. TiO2(B) a new form of titanium dioxide and the potassium octatitanate K2Ti8O17.
    R. MARCHAND, L. BROHAN, M. TOURNOUX. 
    Mat. Res. Bull., Vol. 15, pp. 1129-1133, 1980.
  2. La transformation TiO2(B)  ®   TiO2 Anatase.
    L. BROHAN, A. VERBAERE, M. TOURNOUX, G. DEMAZEAU.
    Mat. Res. Bull., Vol. 17, pp. 355-361, 1982.
  3. Layered K2Ti4O9 and the open metastable TiO2(B) structure
    M. TOURNOUX, R. MARCHAND and L. BROHAN
    Prog. Solid State. Chem., 17, 1-32, 1986.
  4. Order-disorder transition in Na0.25TiO2 bronze : thermodynamic and crystallographic studies
    L. BROHAN, R. MARCHAND and M. TOURNOUX
    J. Solid State Chem., 72, 145-153, 1988.
  5. New hollandite oxides : TiO2(H) and K0.06TiO2
    M. LATROCHE, L. BROHAN, R. MARCHAND and M. TOURNOUX
    J. Solid State Chem., 31, 78-82, 1989.
  6. Structures incommensurables modulées par des défauts dans la transition de phase du bronze Na1-xTi4O8. Etude par diffraction et microscopie électronique.
    D. COLAÏTIS, W. COENE, S. AMELINCK, L. BROHAN, R. MARCHAND.
    Journal of Solid State Chemistry 1989.
  7. Structural origin of the electronic instability in Na0,25TiO2.
    M. EVAIN, M. H. WHANGBO, L. BROHAN, R. MARCHAND.
    Inorg. Chem.Vol 29 n°7, 1990.
  8. CsxTiO2 bronzes with hollandite structure : cationic ordering and physical properties
    M. LATROCHE, L. BROHAN, R. MARCHAND, and M. TOURNOUX
    Mat. Res. Bull., 25, 139-148, 1990.
  9. Electron and X-ray diffraction study of K2SrTi10O22
    M. LE GRANVALET-MANCINI and L. BROHAN
    J. Solid State Chem., 107, 127-133, (1993).
  10. Investigations on layered perovskites : Na2Nd2Ti3O10, H2Nd2Ti3O10 and Nd2Ti3O9.
    M. RICHARD, L. BROHAN and M. tournoux. Soft Chemistry International Symposium.
    Materials Science Forum Vols. 152-153 pp. 245-250 (1994).
    Ed. : J. Rouxel.
  11. Synthesis, characterization and acid exchange of layered perovskites : A2Nd2Ti3O10, (A=Na,K).
    M. RICHARD, L. BROHAN and M. tournoux.
    J. Solid State Chem. 112, 345-354 (1994)
  12. Structural relationship in layered and tunnel alkali-titanates. A new form of potassium octatitanate.
    M. LE GRANDVALET-MANCINI, L. BROHAN, A. M. MARIE and M. TOURNOUX.
    Eur. J. Solid State Inorg. Chem.t.31, p. 767-777 (1994).
  13. Electron Diffraction and HREM of K2Ti8O17, an Ordered Intergrowth of K2Ti6O13 and "K2Ti10O21". M. MANCINI-LE GRANVALET, A. M. MARIE, C. ROUCAU and L. BROHAN.
    Electron Microscopy Vol 2B, p 901-902 (1994).
  14. Contribution to the structural characterization of a sodium yttrium titanate layered perovskite and its protonated forms.
    M. RICHARD, G. GOGLIO and L. Brohan.
    Mater. Res. Bull, Vol 30, No 8 pp 925-931 (1995).
  15. Structural Study of the layered perovskite Na2Nd2Ti3O10 by neutron Diffraction and transmission electron microscopy.
    M. RICHARD, L. BROHAN, A.M. MARIE, C. ROUCAU and M. TOURNOUX.
    J. Solid State Chem. (1995).
  16. Photoconductivity properties of the layered perovskite Nd2Ti2O9r.
    B. DULIEU, J. BULLOT, J. WERY, M. RICHARD, L. BROHAN.
    Physical Review B.Vol 53, Number 16, p 10641-10651 (1996).
  17. X-Rays, Electron Diffraction and H.R.E.M. studies of KHTi4O9, x H2O thermolysis: characterization of K4Ti16O34.
    M. MANCINI-LE GRANVALET, A. M. MARIE, M. CALDES, C. ROUCAU and L. Brohan.
    Microscopy Microanalysis Microstructures Vol. 8, n°3, 203-225, (1997).
  18. (NH3 (CH2)8 NH3)3 (V15O36 Cl) (NH3 )6 (H2O)3 : synthesis and structure determination of a novel centered tricosahedral cluster compound related to the A. Müller-type structure.
    T. Drezen, O. Joubert, M. Caldes, M. Ganne, L. Brohan.
    Journal of Solid State Chemistry. 136, 298-304,  (1998).
  19. Electron diffraction and HRTEM studies of K2Ti8O17 to K4Ti16O34 phase transformation.
    M. MANCINI-LE GRANVALET, A. M. MARIE, M. CALDES, C. ROUCAU and L. Brohan.
    Electron Microscopy, Materials Science 2,Vol. III, p 311-312 (1998).
  20. X-Ray powder diffraction study of LiLaTiO4 (Ln=La, Nd): a lithium-ion conductor.
    V. THANGADURAI, A. K. SHUKLA, J. GOPALAKRISHNAN, O. JOUBERT, L. BROHAN, M. TOURNOUX, Proceeding of the 6th European Powder Diffraction Conference (EPDIC), Budapest, Hungary, 22-25 august 1998. Materials Science Forum by trans tech. (1998)
  21. Layered alkyltrimethylammonium chromates: Thermal and structural investigations, Crystal structure of the anhydrous bis-octadecyltrimethylammonium dichromate.
    N. FOSSÉ, M. CALDES, O. JOUBERT, M. GANNE and L. BROHAN.
    Journal of Solid State Chemistry. 139, p. 310-320 (1998).
  22. Evidence of liquid crystal phase transition in mesostructured alkyltrimethylammonium chromates
    N. FOSSÉ, L. BROHAN.
    Molecular Crystals and Liquid Crystals. 330, P. 129-141 (1999).
  23. Thermal and Structural Investigations of the bis-Hexadecyldimethylammonium Dichromate.
    N. FOSSÉ, L. BROHAN.
    Journal of Solid State Chemistry. 145, p. 655-667 (1999).
  24. Thermal and structural study on liquid-Crystalline Phase Transitions in bis-Alkyl trimethyl ammonium dichromates.
    N. FOSSE, J. Y. MEVELLEC, L. BROHAN
    Molecular Crystals and Liquid Crystals. Vol. 352, p.283-299 (2000).
  25. X-Ray powder diffraction study of LiLaTiO4 (Ln=La, Nd): a lithium-ion conductor.
    V. THANGADURAI, A. K. SHUKLA, J. GOPALAKRISHNAN, O. JOUBERT, L. BROHAN, M. TOURNOUX, Mater. Science Forum Vols. 321-324, p. 965-970 (2000).
  26. Crystal structure and thermal analysis of the tetramethylammonium dichromate and trichromate
    N. FOSSE, O. JOUBERT, M. GANNE , L. BROHAN.
    Solid State Sciences Vol. 3, N°1-2, p. 121-132 (2001).
  27. Synthesis and Structural Characterization of the New Defect Pyrochlore Nd1,68Ti2O6,52
    Ming-Wen CHU, M. Caldes, O. Joubert, M. Ganne, Y. Piffard and L. Brohan,
    Solid State Sciences, 4, p. 167-173 (2002).
  28. X-ray Photoelectron Spectroscopy and High Resolution Electron Microscopy Studies of Aurivillius Compounds : Bi4-x LaxTi3O12 (x=0, 0.5, 0.75, 1.0, 1.5, and 2.0). M.W. CHU, M. GANNE, M.T. CALDES and L. BROHAN. Journal of Applied Physics. Vol. 91, N°5, p. 3178-3187 (2002).
  29. Study of new (–In2S3 containing Na thin films Part I : Synthesis and structural characterization of material. N. BARREAU, J. C. BERNEDE, C. DEUDON, L. BROHAN, S. MARSILLAC, Journal of Crystal Growth 241, p. 4-14, (2002).
  30. Evidence for The Monoclinic Distortion of Ferroelectric Aurivillius Phase:Bi3LaTi3O12
    Ming-Wen CHU, M. T. Caldes, Y. Piffard, A. M. MARIE, E. GAUTIER, O. Joubert, M. Ganne, and L. Brohan,Journal of Solid State Chemistry, Volume 172, Issue 2, p. 389-395 (2003).
  31. X-ray Photoemission Spectroscopy characterization of the electrode-ferroelectric interfaces in  Pt/Bi4Ti3O12/Pt and Pt/Bi3,25 La0,75 Ti3O12 /Pt capacitors : Possible influence of defect structure on fatigue properties. M.W. CHU, M. GANNE, M.T. CALDES E. GAUTIER and L. BROHAN, Physical Review B, 68, 014102-1, (2003).
  32. Bulk and Surface Structures of the Aurivillius Phases: Bi4-x LaxTi3O12 (0 < x < 2.00)
    Ming-Wen Chu, Maria-Teresa Caldes, Luc Brohan, Marcel Ganne, Anne-Marie Marie, Olivier Joubert, and Yves Piffard. Chemical Mater.,16 ,31- 42 (2004).
  33. Characterization of perovskite systems derived from Ba2In2O5¨. Part II : the proton compounds Ba2In2(1-x)Ti2xO4+2x(OH)y (0 £ x £ 1 ; y £ 2(1-x)).V. Jayaraman, A. Magrez, M. Caldes, O. Joubert, F. Taulelle, J. Rodriguez-Carvajal, Y. Piffard and L. Brohan. Solid State Ionics, 170, 25-32 (2004).
  34. Polymère sol-gel à base d’oxyde de titane
    L. Brohan, H. Sutrisno, Y. Piffard, M. Caldes, O. Joubert, E. Puzenat, A. Rouet
    International Publication CNRS patent N° WO 03/064324 A3 (07/08/2003)

    - European (EP) CNRS patent n° 03 734 737.4 (14/01/2003)

    - Japan (JP) CNRS patent n° 2003-563956 (03/08/2004)
    - United States (US) patent n° (in progress)

  35. Aquo-oxo chlorure de titane, procédé pour sa préparation.
    L. Brohan, H. Sutrisno, E. Puzenat, A. Rouet, H. Terrisse
    French CNRS patent priority N° 0305619 (09/05/2003)
  36. Titanium aquo-oxochloride and preparation method thereof.
    L. Brohan, H. Sutrisno, E. Puzenat, A. Rouet., H. Terrisse
    - International Publication n° WO 2004/101436 A2 ( 25/11/2004)

    - European CNRS patent (EP) n° 04 742 604.4 (24/11/2005)

    - Japan (JP) CNRS patent n°2006-530327 (16/10/2006)

    - United States (US) CNRS patent n° 018344/0578 (04/02/2006)

  37. Photosensitive titanium oxo-polymers: synthesis and structural characterization. Thomas Cottineau, Mireille Richard-Plouet, Annabelle Rouet, Eric Puzenat, Hari Sutrisno, Yves Piffard, Pierre-Emmanuel Petit and Luc Brohan. Chem. Mater. 2008, 20, 1421-1430.5,1
  38. Evidence of interfacial charge transfer upon UV-light irradiation in novel titanium oxide gel, T. Cottineau, L. Brohan, M. Pregelj, P. Cevc and M. Richard-Plouet, D. Ar?on, Advanced Functional Materials, 2008, 18, 1-9. 6,8
  39. (101)-Exposed Anatase TiO2 Nanosheets, C.-W. Peng, T.-Y. Ke, L. Brohan, M. Richard-Plouet, J.-C. Huang, E. Puzenat, H.-T. Chiu, and C.-Y. Lee, Chem. Mater. 2008, 20, 2426-2428. 5,1
  40. Interconversion of Rutile TiO2 and Layered Ramsdellite-Like Titanates: New Route to Elongated Mesoporous Rutile Nanoplates Peng Chih-Wei; Richard-Plouet Mireille; Tsai Min-Chiao; Lee Chi-Young; Chiu, Hsin-Tien; Petit Pierre-Emmanuel; Sheu Hwo-Shuenn; Lefrant S.; Brohan Luc, Crystal Growth & Design, 2008,  8(10),  3555-3559. 4,34
  41. Low Temperature Synthesis of Nanocrystallized Titanium Oxides with Layered or Tridimensional Frameworks, from [Ti8O12(H2O)24]Cl8 · HCl ·7H2O Hydrolysis, C.-E. Liu, A. Rouet, H. Sutrisno, E. Puzenat, H. Terrisse, L. Brohan and M. Richard-Plouet. Chem. Mater. 2008, 20, 4739–4748.5,1

  42. Chimie-Douce route to Sodium Hydroxo Titanate Nanowires with Modulated Structure and Conversion to Highly Photoactive Titanium Dioxides. Peng, C-W; Richard-Plouet, M; Ke, T-Y; Lee, C-Y; Chiu, H-T; Marhic, C; Puzenat, E; Lemoigno, F; Brohan, L. , Chem. Mater. 2008, 20(23),  7228-7236. 5,1
 
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