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Silicon oxynitride (SiOxNy) thin films are widely encountered in today’s major key enabling technologies. Exhibiting tunable properties dependent on the nitrogen content, they attract attention in applications requiring thermal stability, high dielectric constant, corrosion resistance, surface passivation, and effective ion diffusion barrier. Identification of the minimum desired level of nitrogen incorporation for each application is important for simultaneously optimizing material properties and the deposition process. In this context, we study the structural and functional properties of SiOxNy films deposited from tris(dimethylsilyl)amine (TDMSA), O2, and NH3, using conveniently scalable atmospheric pressure chemical vapor deposition (CVD) at moderate temperature (600−650 °C). A suite of characterization techniques including spectroscopic ellipsometry (SE), Fourier-transform infrared spectroscopy (FT-IR), ion beam analyses (IBA), nanoindentation, nanoscratch, Xray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HR-TEM), water wettability, surface roughness, and resistance to wet etching corrosion are implemented in order to establish the relevant structure−composition−properties correlations. The produced SiOxNy films are smooth and amorphous, exhibiting beyond state-of-the art corrosion resistance in standard though particularly aggressive hydrofluoric buffer oxide etchant (BOE) 6:1 solution, with remarkable near-zero etching rate values. Compositional trends reveal the presence of C and H atoms, yet their incorporation has insignificant effect on the films RMS roughness and wet etching corrosion resistance. Coupled SE, FT-IR, and XPS analyses reveal that the SiOxNy network appears to undergo a sharp transition between 4 and 6 atom % N, affecting hardness and Young’s modulus. Globally, material properties such as scratch resistance, surface roughness, and corrosion resistance are improved with increasing nitrogen content. Additionally, the asymmetric stretching silicon nitride (Si3N4) FT-IR absorption at ca. 850 cm−1 is used to track the binding configuration in the amorphous SiOxNy network. Correlation of the elemental environment and chemical bonding to the corresponding process conditions can aid in identifying the process margins for desired intrinsic and/or functional properties.

International audience; An apparent kinetic model is developed for a novel chemical vapor deposition (CVD) process of silicon oxynitride (SiO x N y) films from tris(dimethylsilyl)amine (TDMSA) and O 2 , operating at moderate temperature (600-650 • C) and at atmospheric pressure. The definition of reaction pathways and the extraction of kinetic information is based on recently reported results of the gas phase composition, complemented by solid phase characteristics obtained by spectroscopic ellipsometry (SE) and ion beam analyses (IBA). Incorporation of carbon (up to 20 at. %) is considered alongside nitrogen (up to 25 at.%) for variable O 2 flow rates (0.3-1.2 sccm). This combined gasand solid-phase analysis is utilized to identify the main gaseous species and provide insight into the deposition mechanism. A silicon-and a nitrogen-centered radical intermediates are considered as the primary species of the mechanism, based on evidence from gas phase characterizations. A third, fictitious, nitrogen-and carboncontaining molecule is also conceptualized to account for carbon incorporation. Eight chemical reactions are defined alongside their respective kinetic parameters and are implemented in the ANSYS® FLUENT® computational fluid dynamics (CFD) code. Upon validation, the model allows for the successful prediction of local deposition rates and SiO x N y film composition containing non-negligible carbon, marking it as the first kinetic model able to represent the main chemical mechanisms involved in the CVD of a four-component material. The reported combined approach could be applied to other existing or new CVD chemistries forming multicomponent thin films, favoring their implementation in original applications.

International audience; In a companion paper, it has been demonstrated the remarkably beneficial effect of palygorskite clay (Pal) fibers as support material coupled to appropriate thermal treatments and aging under CO2 atmosphere in monitoring the phase composition of Ag2CO3-Pal composite. In this new nanocomposite material, the structure of the functional component Ag2CO3 can be controlled from 100% stable monoclinic (m) to 100% metastable hexagonal β through an adjusted mixture of m- and β-Ag2CO3. The present study deals with the assessment of the visible photocatalytic properties of these various nanocomposite materials towards the removal of Orange G dye from aqueous solutions. It was found that the Ag2CO3-Pal nanocomposite in which Ag2CO3 was single-phased and crystallized with the stable monoclinic structure was more active than the one crystallizing entirely with the metastable β-Ag2CO3 structure. Nevertheless, the composite material containing a mixture of both Ag2CO3 phases with a relative content of 32% of β- and 68% of m-phase was found to be the most photoactive compound of the series. This behavior reveals likely a synergetic effect between both phases in the photocatalytic degradation of the dye under visible light.

The chemical or mechanical performance of amorphous SiO2 films depend on intrinsic physicochemical properties, which are intimately linked to atomic and molecular arrangements in the Si–O–Si network. In this context, the present work focuses on a comprehensive description of SiO2 films deposited from a well-established chemical vapor deposition process involving tetraethyl-orthosilicate, oxygen and ozone, and operating at atmospheric pressure in the range 400–550 °C. The connectivity of the silica network is improved with increasing the deposition temperature (Td) and this is attributed to the decreased content of hydrated species through dehydration-condensation mechanisms. In the same way, the critical load of delamination increases with increasing Td thanks to the silicon substrate oxidation. The utilization of a O2/O3 oxidizing atmosphere involving the oxidation of intermediates species by O2, O3 and O., allows increasing the deposition rate at moderate temperatures, while minimizing carbon, H2O and silanol contents to extremely low values (4.5 at.% of H). The SiOx stoichiometry and Td interplay reveals two distinct behaviors before and above 450 °C. The best corrosion resistance of these films to standard P-etching test is obtained for the minimum silanol content and the best network molecular ordering, with an etching rate of 4.0 ± 0.1 A/s at pH = 1.5. The elastic modulus and hardness of the films remain stable in the investigated range of deposition temperature, at 64.2 ± 1.7 and 7.4 ± 0.3 GPa respectively, thanks to the low content in silanol groups.

International audience; Tris(dimethylsilyl)amine (TDMSA) is used in the presence of O2 and NH3 for the atmospheric pressure chemical vapor deposition (CVD) of conformal, corrosion barrier silicon oxynitride (SiOxNy) films at moderate temperature. Plausible decomposition pathways taking place during the process, as well as resulting gas-phase by-products, are investigated by an innovative methodology, coupling solid-state films characteristics with gas phase analysis. Liquid NMR, gas chromatography coupled with mass spectrometry (GC-MS) and electron spin resonance (ESR) allow probing stable compounds and radical intermediate species in the gas phase. At least fifteen by-products are identified, including silanols, siloxanes, disilazanes, silanamines, and mixed siloxane–silanamine molecules, in addition to more usual compounds such as water. The radical dimethylsilane, Me2HSi˙, is noted across all experiments, hinting at the decomposition of the TDMSA precursor. Deposition of SiOxNy films occurs even in the absence of NH3, demonstrating the judicious choice of the silanamine TDMSA as a dual source of nitrogen and silicon. Additionally, the presence of Si–H bonds in the precursor structure allows formation of SiOxNy films at temperatures lower than those required by other conventional silazane/silanamine precursors. Addition of NH3 in the inlet gas supply results in lower carbon impurities in the films. The identified by-products and formulated decomposition and gas-phase reactions provide stimulating insight and understanding of the deposition mechanism of SiOxNy films by CVD, offering possibilities for the investigation of representative chemical models and process simulation.

International audience; Silica and silica-based materials with tunable functionalities are frequently encountered in low-k material applications, porous membranes, and microelectonic devices. In the present study, an innovative O2 /O3 assisted CVD process for the deposition of such films at moderate temperature is presented, based on a dual precursor chemistry from hexamethyldisilazane (HMDS) and tetraethyl orthosilicate (TEOS). Films with tunable carbon content were obtained through variation of the HMDS flow ratio. A comprehensive FT-IR study reveals the transition of the material from a SiOxCyH type film containing-CH3 moieties, to a methyl-free SiOx film with the increase of the temperature. At the same time the water contact angle of 81.0° at 400 °C is decreased to 52.8° at 550 °C, related to the absence of methyl moieties in the latter. Ion beam analysis (IBA) confirms the lack of carbon in the films when deposition temperatures are equal to or exceed 500 °C. The resistance to liquid corrosion is investigated as a function of the deposition temperature; SiOx type films present a low Pliskin etching rate of 15 Å.s−1 , with this value increasing to 60 Å.s−1 for the SiOxCy:CH3 films produced at the lower temperatures. It is found that the addition of HMDS to a TEOS chemistry can be utilized to modulate the film composition from SiOx to SiOxCyH and by such, tune the film functional properties, in particular its etching rate, opening the way to the development of new sacrificial films.

International audience; Nanoindentation is a well-known technique to assess the mechanical properties of bulk materials and films. Despite that, nanoindentation of thin films is not straightforward, given that the measured properties are composite information from a film/substrate system and depend on the indentation depth. By using dynamic indentation experiments and analytical or empirical models, we assessed the intrinsic film properties of chemical vapor deposited silicon oxide (SiO x) and silicon oxycarbide (SiO x C y) thin films with thicknesses ranging from 60 to 700 nm. In this work, the Bec rheological model and several mixing laws were reviewed. Measured Young modulus appeared to be affected by the substrate properties more than hardness: for the thinnest films, moduli were measured at ca. 90 GPa whereas intrinsic moduli were calculated at ca. 50 GPa. Using calculated intrinsic film modulus and hardness, it was possible to establish correlations between these properties, the chemical composition and the structural organization of the films.

International audience; Coating complex surfaces by functional amorphous silica films for new applications including energy harvesting and health depends on the operating range and robustness of their deposition process. In this paper, we propose a new kinetic model for the atmospheric pressure chemical vapor deposition of SiO2 films from TEOS/O2/O3 valid in the 150−520 °C temperature range, thus allowing for treating thermally sensitive substrates. For this, we revisit reported chemical schemes in Computational Fluid Dynamics simulations considering original experimental data on the deposition rate of SiO2 films from a hot-wall reactor. The new model takes into account for the first time a thermal dependency of the direct formation of SiO2 from TEOS and O3 and yields excellent agreement in both shape and value between experimental and calculated local deposition rate profiles. The model provides non-measurable information such as local distributions of species concentration and reaction rates, which are valuable for developing optimized CVD reactor designs. Original solutions for the introduction of the reactants are proposed, to uniformly coat complex and/or large parts at a wide temperature range.

International audience; Keywords: Copper(I) cyclopentadienyl triethylphophine Copper Thin films Metal-organic chemical vapor deposition Coalescence Nucleation Morphology Image analysis A B S T R A C T The rough, even discontinuous morphology of vapor-deposited copper films inhibits their attractive electrical properties. In the present study, we investigate the influence of deposition time, deposition temperature, and the flow rate of the precursors on the morphology of Cu films deposited from metalorganic chemical vapor de-position. We show that it is necessary to purify the copper(I) cyclopentadienyl triethylphophine (CpCuPEt 3) precursor in order to improve its stability and volatility. We also determined its saturated vapor pressure law, logP sat (Pa) = 8.614-2272/T (K). The Arrhenius plot of the global deposition reaction of Cu films in the presence of hydrogen between 431 and 523 K shows a low apparent activation energy of 10 kJ/mol. Electron probe microanalysis, grazing incidence X-Ray diffraction, and image analysis of the micrographs obtained by top-down surface scanning electron microscopy reveal metallic films composed of Cu islands. Their size and packed density increase and, ultimately, the islands coalesce with increasing precursor flow rate and, to a lesser extent, with increasing deposition temperature.

International audience; Two new organiceinorganic materials based on MoePOM, namely (iPr2NH2)2.((CH3)2NH2)2.[Mo8O26] (1) and (Pr2NH2)4$[Mo8O26] (2), have been synthesized by a non-hydrothermal method at room temperature and characterized by single crystal X-ray diffraction, thermal gravimetric analysis (TGA) and vibrational spectroscopy. The compound (1) is a b-[Mo8O26]4- anion which crystallizes as a mixed salt of both dimethylammonium [(CH3)2NH2]þ and diisopropylammonium [iPr2NH2]þ. The interaction between anions and cations leads to an inorganic-organic band structure. Similarly, in compound (2), the interconnection of b-[Mo8O26]4- anions with dipropylammonium [Pr2NH2]þ cations gives an inorganicorganic band structure. In both compounds, the cations interact with two different sites of the cluster: a fundamental site formed by four highly nucleophilic terminal oxo ligands, and a second site which is composed of Ot, m2-O and/or m3-O oxygen groups. A remarkable difference between the two compounds is that in compound (2) interactions between the bands involve only Van der Waals forces, whereas in compound (1) the bands interact also through hydrogen bonds.

International audience; Three new dinuclear molybdenum(VI) oxalate (Pr2NH2)4·[Mo2O6(C2O4)2] (1), (iPr2NH2)4·[Mo2O6(C2O4)2] (2) and (HDabco)4[Mo2O6(C2O4)2]·2H2O (3) compounds, have been prepared by one pot-synthesis at room temperature and characterized by single crystal X-ray diffraction and vibrational spectroscopies. Each compound contains the binuclear [Mo2O6(C2O4)2]4− anion where each molybdenum is in an octahedral MoO6 environment. In compound (3), the interconnection between [Mo2O6(C2O4)2]4− anions, [HDabco]+ cations and water molecules (H2O) leads to an infinite inorganic-organic chain structure. Similarly, in compounds (1) and (2) the interactions between [Mo2O6(C2O4)2]4− anions and respectively [Pr2NH2]+ and [iPr2NH2]+ cations leads to an infinite inorganic-organic chain structure. A remarkable difference between the compounds is that in compounds (1) and (2) interactions between the chains involve only Van der Waals forces giving rise to layer-like structures, which also interact between them only by Van der Waals forces, whereas in compound (3) the chains interact also through hydrogen bonds giving a 3D supramolecular structure. The thermal properties of the compounds were investigated through thermogravimetric and differential thermal analyzes. The differences in the thermal decomposition of the compounds in the solid state are discussed in relation with their crystal structure. Cyclic voltammetry shows that the [Mo2O6(C2O4)2]4− anion can be reduced in both aprotic solvent and water.

International audience; This study reports an original remarkable effect of fibrous palygorskite clay mineral in the stabilization at the ambient temperature of the metastable hexagonal β-phase of Ag2CO3 along with the stable monoclinic one (m-Ag2CO3) and the refinement of their particles size (≈5–10 nm). These structural and microstructural features likely arise owing to heterogeneous nucleation induced by the surface of palygorskite fibers between CO32– anions in solution and Ag+ exchanged palygorskite (Ag+-Pal) as reactants kept maturing for short periods, which should not exceed 1 h. Besides, the phase composition of Ag2CO3 supported on palygorskite, namely β- and m-structures can be monitored by carrying on appropriate low temperature treatments under CO2 atmosphere coupled with aging during several months in such a way that either pure β or m single-phases as well as biphased mixtures with controlled composition can be obtained. Taking into account experimental results and literature data, a growth mechanism is discussed.

International audience; This study aims at determining suitable conditions for the preparation of the best organobeidellite starting material used for the development of efficient mesoporous TiO2 supported beidellite (Bd) photocatalysts. For this purpose, organo-modifications of natural Bd from Agadir Basin (Morocco) were achieved. The influence of (i) the length of alkyl chains Cn (n = 8, 12, 14 and 16) of n-alkyl ammonium surfactants CH3(CH2)n-1NH3+ and (ii) the amount of C16 surfactant ranging from 1 to 5 times the smectite (Sm) cation exchange capacity (CEC) on the structure of organo- Bd was studied. XRD, TEM, TG-DTA and FTIR results are consistent with the intercalation of cationic surfactants species in Bd interlayer spaces according to different conformations yielding to their expansion. The interlayer expansion magnitude increased both with the length of alkyl chain and the amount of C16 surfactant. Organomodification with increasing surfactant load beyond 1CEC besides yielded to the adsorption of increasing excess on external surfaces of Bd particles. These controlled structural modifications will be used further in the functionalization of this Bd by TiO2 nanoparticles to produce efficient supported TiO2-Bd photocatalysts.

TiO2/stevensite nanocomposite photocatalysts were synthesized by a solvothermal method using TiCl3/HCl as reactants and the stevensite clay mineral extract as support. The prepared photocatalyst samples were then characterized using various techniques such as X-ray diffraction (XRD), Infrared spectroscopy (IR) and Transmission Electron Microscopy (TEM). The Points of Zero Charge (PZC) of the various samples were evaluated by titration of the non-modified and the Ti-modified clay aqueous dispersions, with cationic surfactant solutions. The photocatalytic activity of the resulting nanocomposites samples were evaluated for the removal of Orange G (OG) from aqueous solution as a model dye pollutant. The data indicate that the formation of Na+-stevensite by the TiO2 particles leads to TiO2/stevensite nanocomposites having higher specific surface areas and mesopore volumes, and lower PZC values. Further, the photocatalytic activity was greater for the TiO2/stevensite nanocomposites having the greatest Ti amount, as compared to a pure TiO2 sample, and increased with the increase of the TiO2 content in the TiO2/stevensite nanocomposites.

This study deals with the immobilization of mixtures of two semiconductor oxides CuO and TiO2 on fibrous palygorskite clay mineral in order to evaluate their photocatalytic activity for removing Orange G dye as model pollutant from aqueous solutions. The elaboration of CuO–TiO2/Palygorskite nanocomposites was carried out by impregnation with Cu2+ of before hand synthesized TiO2 supported palygorskite (Pal) followed by air annealing for 5 h at 550 °C. In the composite materials, different CuO to CuO + TiO2 molar ratios were used in order to obtain a CuO content in the range 13–30 mol.%. XRD, SEM and TEM equipped with elemental EDS analysis are concordant for showing the crystallization of anatase TiO2 along with CuO whose average size of nanoparticles (NPs) are in the range 6 to 20 nm as determined by TEM. By increasing the CuO content the average size of this oxide remains constant at about 10 nm while that of TiO2 NPs is slightly decreasing from 8.4 to 5.1 nm. Both oxide NPs were successfully attached on palygorskite fibers where they form CuO–TiO2 heterojunctions (grain boundaries like). The CuO–TiO2/Pal supported photocatalyst containing 23% of CuO was found to be the most photoactive material but itremained less active than TiO2/Palygorskite supported photocatalyst. The photocatalytic activity of the mixed nanocomposites is not readily correlated with only one of their main features as CuO content or the average crystallite size of functional oxides indicating that if there are synergistic effects there are also antagonistic effects in particular for high CuO contents.

We present first experimental results obtained with a newly patented high-temperature resistivity measurement apparatus. This technique is of great interest for monitoring the behaviour of a surface layer submitted to high temperature, either during its processing or while the functional surface is used. The innovation resides in the combination of features that are available commercially or have previously been reported by research groups worldwide, but isolated. Resistivity measurements can be performed under vacuumor controlled atmosphere, fromroomtemperature to 1250°C, on samples as low as 10*10mm2 in size. Technical details about the apparatus are presented. Then, we show that high-temperature resistivity measurements performed on a platinum sheet compare well with available data, and validate the prototype measurement head. Finally, we explore the monitoring of phase transitions occurring in an Al/Cu bilayer processed by metallorganic chemical vapour deposition, while a temperature ramp is applied. The high-temperature resistivity plot is very well explained by the following sequence of phase formation: Al + Cu!θ-Al2Cu+ Cu+ Al!d-Al2Cu3 + g-Al4Cu9+Cu!d-Al2Cu3 + g-Al4Cu9+Cu+a-(Cu), as determined by hightemperature X-ray diffraction.

International audience; Cette étude porte sur la fonctionnalisation par TiO2 d'une argile marocaine de type beidellite et sur l'évaluation de son activité photocatalytique pour l'élimination d'un colorant anionique : l'orange G (OG), utilisé dans l'industrie textile. Les échantillons argileux ont été caractérisés, avant et après fonctionnalisation, par DRX, MEB et MET couplé à l'analyse EDX, TG-ATD, FTIR, ICP et RMN du solide. La beidellite est aluminifère, dioctaédrique, de formule chimique (Si7,57Al0,43)8 (Al2,75Fe0,73Mg0,38Ti0,14)4 (Na0,37K0,23Mg0,01) avec une CEC, une surface spécifique et un volume poreux total de l'ordre de 48 méq/100 g, 72 m2/g et 0,128 cm3/g respectivement. Les matériaux argileux nanocomposites obtenus sont constitués de nanoparticules de TiO2 (taille moyenne 10 nm) supportées par les feuillets de la beidellite. Leurs surfaces spécifiques sont quasiment du même ordre de grandeur que celle de la beidellite tandis que leurs volumes poreux augmentent pour atteindre 0,226 cm3/g. L'échantillon calciné à 600 ◦C, dans lequel TiO2 est sous forme d'anatase, manifeste une activité photocatalytique remarquable vis-à-vis de l'élimination de l'OG en milieu aqueux.

Chemical vapour deposition and atomic layer deposition using precursors that are solids at ambient temperature and pressure present challenges due to the often low saturating vapour pressure of these compounds. Additional concerns arise from the difficulty to maintain a reproducible and stable precursor flow rate to the deposition chamber and from the possible particle contamination if suitable safeguards are not built into the precursor delivery line. In the present contribution, SUBLIBOX, a pilot industrial scale sublimator is presented. SUBLIBOX is based on a new sublimation process involving gas-solid fluidization technology. Aluminum acetyl–acetonate [Al(acac)3], a promising precursor for the processing of alumina films despite its low saturated vapour pressure, is used as a model, though technologically interesting system. Mass balance measurements, involving trapping of the sublimed precursor at the exit of the sublimation chamber, reveal that SUBLIBOX ensures (a) stable, (b) efficient, (c) reproducible and (d) long term precursor vapour flow rates. The process is particularly well adapted for delivering vapours to CVD reactors for coatings on glass and stainless steel or for producing optical fibbers preforms by various techniques.

5 páginas, 9 figuras.-- et al., Well-dispersed nanoparticles of molecule-based conductors, namely TTF·TCNQ and TTF[Ni(dmit)2]2, have been prepared in organic solution using 1-butyl-3-metylimidazolium tetrafluoroborate as a stabilizing agent. TTF·TCNQ nanoparticles (prepared at room temperature) exhibit sizes ranging from 2 to 5.5 nm, whereas those of TTF[Ni(dmit)2]2 (prepared at −80 °C) are larger (sizes in the 16–45 nm range). Nanoparticle powders have been characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and by transport measurements., This work was supported by the Centre National de la Recherche Scientifique (France), by the Ministerio de Ciencia y Tecnologia (Spain), through project FIS2006-12117-C04-01, and by the Generalitat de Catalunya (SGR 00909).

Various reactive gas phase treatments have been investigated as surface functionalization dry processes with the goal to improve the wettability of parylene C films, keeping good optical properties in the visible range. The films were grown on different substrates by chemical vapor deposition with thicknesses ranging from 300 to 1630 nm. The polymer surface was treated under ultra violet (UV) irradiation at 254 nm in reactive atmospheres including He, H 2 O, H 2 O 2 , O 2 and ambient air. The UV/O 2 treatment is the most efficient since the water contact angle decreases from 100° to 6° while the transmittance is maintained at 90% in the visible wavelengths. Furthermore it exhibits long life stability. The functionalization mechanism is discussed in relation with previous reports.

This paper reports on the use of a novel copper(I) amidinate compound [Cu(i-Pr-MeAMD)]2 to produce copper films in conventional low pressure CVD using hydrogen as reducing gas-reagent. Copper films were deposited on steel, silicon and SiO2/Si substrates. Their composition, morphology, conductivity and growth rate were investigated in the temperature range 200 - 350 oC at total pressure of 10 Torr. XRD and EPMA confirmed that the films are composed of polycrystalline copper metal without carbon and nitrogen impurities.

International audience; Decomposition of CpCuPEt3 (Cp=NNN(η5-C5H5)) and MOCVD of Cu films from CpCuPEt3 have been investigated in the frame of an ongoing project on the processing of Cu-containing coatings. The behaviour of CpCuPEt3 vapours under heating conditions was studied by in situ mass spectrometry. It was established that this compound is monomeric in gas phase. Its decomposition mechanism on hot surface was proposed. From mass spectroscopy experiments, it was established that decomposition in vacuum begins at 150 °C with evolution of PEt3. Beyond 270 °C, formation of cyclopentadiene is observed, indicating that a change in decomposition mechanism occurs. The saturating vapour pressure of CpCuPEt3 was estimated through static method, in order to optimize transport conditions and to control the molar fraction of the precursor in the gas phase. Finally, growth rate and microstructure of MOCVD processed Cu films from CpCuPEt3 have been investigated.

This work deals with the study of the effect of the amount of cethyltrimethylammonium bromide (CTAB) surfactant, used in the preparation of starting organobeidellites, on physico-chemical properties and photocatalytic activity of TiO 2 supported beidellite (Bd) nanocomposites against the removal of Orange G (OG) dye from aqueous media. A structural study of organobeidellites used as starting materials was reported in a companion paper. Here, physico-chemical characterizations of the nanocomposite photocatalysts show that TiO 2 supported on Bd beforehand organomodified with an amount of CTAB equivalent to 3 CEC of smectite (3CTA + –Bd) exhibits thin fine grained (≈ 10 nm) features which remarkably remained stable in the form of photoactive anatase up to 750 °C. Comparatively, the TiO 2 coating grown on Bd previously rendered organophilic by using an amount of CTAB equivalent to 5 CEC of Clay mineral (5CTA + –Bd) appears thicker and more porous with larger nanoparticles (≈ 25 nm) which is prone to be readily converted into less photoactive rutile as observed near 700 °C. This is likely due to its development mainly outside Bd interlayer spaces promoted by outer organophilic environment created by the adsorption of CTA + excess. In both cases, anatase is still present as minor phase up to 900 °C. As a result of these differences a significant improvement of the photocatalytic activity of TiO 2 supported Bd nanocomposite prepared starting from 3CTA + –Bd is observed compared to that from 5CTA + –Bd. For instance, the total elimination of the pollutant from the aqueous solution occurs within about 45 min when using the 3CTA + –Bd–TiO 2 photocatalyst instead of 90 min using the 5CTA + –Bd–TiO 2 sample. Furthermore, the best TiO 2 –Bd supported photocatalyst is also found more efficient than a pure TiO 2 xerogel sample.

International audience; Cu/Pd alloys were deposited onto Si(100) and SiO2 (fused silica) substrates by MOCVD from PdL2×CuL2, (L=2-methoxy-2,6,6-trimethylheptane-3,5-dionate), a new single source bimetallic precursor. Deposition was performed at 10 Torr in a temperature range between 200 °C and 350 °C and was assisted by vacuum ultraviolet (VUV) irradiation of the precursor vapor from an excimer Xe-lamp. It was shown that the elemental and phase composition of the films can be controlled by varying the deposition temperature and by stimulating by VUV the precursor decomposition. The bulk compositional properties of the obtained films confirmed the feasibility of proposed approach and precursor to prepare Pd alloy membrane materials by the CVD method.

International audience; Due to attractive surface properties and to intrinsic brittleness of Complex Metallic Alloys (CMAs), most of their potential applications involve materials with high surface-to-volume ratios, including thin films and coatings. While physical vapor deposition techniques are efficient for the processing of CMA films on line-of-sight surfaces, chemical vapor deposition (CVD) is well positioned for their application on complex surfaces. However, for CVD process to be implemented efficiently in the processing of CMA films a number of challenges must be addressed. Because numerous CVD reagents, commonly called precursors, are low vapor pressure liquids or solids, one of these challenges is the production of vapors of such precursors, which are decomposed in the deposition chamber to provide the desired film. Such a production has to be ensured at high rate and must be reproducible and stable during the whole process. Actual solutions to this question involve (i) bubbling inert gas through thermally regulated liquid precursors, (ii) leaching the surface of fixed precursor powder beds, and (iii) in situ generating the precursor flow by passing a reactive gas through a thermally regulated bed of the metallic element to be transported. Such solutions neither may be satisfactory for actual R&D needs nor may be transferable to industrial environments. These reasons are in part responsible for the limited implementation of advanced materials (including CMA-based ones) in numerous industrial and hence societal needs. More recently, innovative solutions have been proposed to feed deposition systems based on vapor phase chemical techniques (CVD and Atomic Layer Deposition, ALD). Such solutions are Direct Liquid Injection (DLI) of dissolved solid precursors and also sublimation of the latter in fluidized beds or in elaborated fixed beds. Such technological responses show promise for industrial applications of CVD, especially for the deposition of metals and ceramic compounds for which the available molecular and inorganic precursors present low vapor pressures. This review provides an overview of the methods by which precursor vapors are transported to the deposition chamber. Early and recent patents dedicated to such technologies will be revisited and considered in the light of the deposition of multimetallic alloy coatings.

TiO2 thin films were deposited under atmospheric pressure by chemical vapor deposition using metal organic precursors (AP-MOCVD) in the temperature range 350–700 °C on Si(100) and stainless steel substrates. Titanium tetraisopropoxide (TTIP) was used as metal source. The influence on the growth process of an oxidant co-reagent (O2 and H2O) has been investigated. TTIP mole fraction and the substrate temperature are the major parameters which permit a good control of the morphology, the microstructure, the composition and the growth rate of these functional oxide thin films. Addition of O2 in the input gas phase does not change significantly the main features of the layers. By contrast, TTIP/H2O gas mixtures exhibit a higher reactivity leading to the deposition of TiO2 at lower temperature and with a higher growth rate. For instance, the deposition rate at 450 °C is approximately 440 and 90 nm/min with and without H2O vapor, respectively. Single-phased (anatase or rutile) and bi-phased coatings with a controlled composition can be deposited depending on the temperature and the TTIP mole fraction.

Nanoparticles of nickel have been obtained in solution through reaction of an organometallic precursor, Ni(COD)2 (COD=cycloocta-1,5-diene), with dihydrogen, in the presence of various stabilizing agents. X-ray diffraction studies evidence a face-centered-cubic structure for all samples. Spherical isolated superparamagnetic nanoparticles (d∼4.5 nm) are produced in the presence of poly(N-vinylpyrrolid-2-one). They display a magnetization value comparable to that of bulk nickel, as determined from superconducting quantum iinterference device (SQUID) measurements. Exposure of the surface of the nanoparticles to CO, leading to CO coordination as monitored by infrared spectroscopy, or to methanol, strongly reduces their magnetization. This reduction corresponds respectively to one or two magnetically inactive layers of nickel atoms at the nanoparticles surface. The production of elongated nanoparticles was favored when either trioctylphosphineoxide or hexadecylamine (HDA) were used as stabilizing agents. In thi...

The synthesis and characterisation (X-ray structure and magnetism) of metal complexes (Ni, Au) with the [Mn(Cp*)2]+ cation and the dmit2− and dmid2− ligands are reported. [Mn(Cp*)2][Ni(dmit)2] (1) and [Mn(Cp*)2][Au(dmit)2] (2) exhibit the same structural arrangement, built on stacks of [Ni(dmit)2]− pairs separated by two [Mn(Cp*)2]+ cations, showing a ···D+D+A−A−D+D+A−A−··· motif. On the contrary, the dmid2− derivative [Mn(Cp*)2][Ni(dmid)2]·CH3CN (3) exhibits a totally different structure, built on mixed layers composed of one [Ni(dmid)2]− unit separated by two [Mn(Cp*)2]+ cations, showing a ···D+D+A−D+D+A−···motif. The layers are separated from each other by perpendicular [Ni(dmid)2]− units and solvent molecules. Compound 2 exhibits antiferromagnetic interactions, whereas 1 and 3 exhibit ferromagnetic interactions at low temperature. Moreover, as confirmed by AC and DC magnetic susceptibility measurements, 1 is a ferrimagnet, the first ever derived from a 1,2-bis-dithiolene ligand. The ferromagnetic interactions in 1 and 3 are explained using the McConnell I mechanism. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

Decomposition of the organometallic precursor [In(η5-C5H5)] in toluene in the presence of methanol (8 vol.-%) at room temperature leads to the immediate formation of aggregates of indium nanoparticles of 15 ± 2 nm mean diameter. The aggregates are roughly spherical with a mean size of 400 ± 40 nm. The particles were characterized by means of transmission electron and high-resolution transmission electron microscopies (TEM and HRTEM), and X-ray diffraction (XRD) studies indicate that the powder consists of the tetragonal phase of indium. The thermal oxidation in air of these nanoparticles yields well-crystallized nanoparticles of In2O3 with unchanged morphology (aggregates of nanoparticles of 16.6 ± 2 nm mean diameter with aggregate mean size of 400 ± 40 nm) and without any sign of coalescence. XRD pattern shows that the powder consists of the cubic phase of In2O3. The electrical conductivity measurements demonstrate that this material is highly sensitive to an oxidizing gas such as nitrogen dioxide and barely sensitive to a reducing gas such as carbon monoxide. Its association with SnO2-based sensors allows the selective detection of carbon monoxide (30 ppm) and sub-ppm amounts of nitrogen dioxide (400 ppb) in a mixture at 21 °C and at a relative humidity of 60 %.

Deposition of uniform coatings on relatively large size and/or complex shaped pieces require generally isothermal rather than cold-wall chemical vapor deposition (CVD) reactor. After a review of the state-of-the-art of Ir CVD processes aiming the selection of the starting materials, Ir thin films were deposited on W substrates by thermal decomposition of Ir(COD)(MeCp) either in presence of H2 or O2. The growth was carried out in a horizontal hot-wall metal–organic chemical vapor deposition reactor under reduced pressure and low temperature (573–673 K). Using this CVD reactor the process is more difficult to control using H2 rather than O2 as co-reagent. The purity, the microstructure, the growth rate and the thickness uniformity depend on the deposition conditions. Oxygen avoids carbon incorporation in the layers and enhances significantly the growth rate. However, co-deposition of Ir and IrO2 was observed using a high excess of O2. Polycrystalline, compact, untextured and pure Ir coatings were deposited with a satisfactory thickness uniformity over a length of approximately 15 cm and with a typical thickness of 1–2 μm. These coatings have attractive properties to be used as oxidation barriers at high temperature. Optimal deposition conditions were found using the trends predicted by a kinetic model simulating the growth rate along the CVD reactor. A good thickness uniformity along the reactor requires a very short residence time of the reactive species. As a result, the conversion rate is low leading to a poor efficiency of the process.

SnO2 coatings have been deposited by metal-organic chemical vapor deposition (MOCVD) on Ti plates using SnEt4 and O2 as reactive gas mixture. The thickness, morphology and microstructure of these coatings are controlled by the growth conditions. The deposition process has been used for the preparation of Ti/IrOx/SnO2 electrodes that were tested for the anodic oxidation of organic pollutants in industrial wastewater. These anodes exhibit a high overpotential for oxygen evolution and a good efficiency for the elimination of total organic carbon (TOC) from wastewater. Electrochemical impedance measurements were used to characterize the activity of the interface SnO2/aqueous media as a function of time during the oxidation process. The influence of the grain size, thickness and surface pre-treatment of the Ti substrate on the electrocatalytic properties is discussed.

Nickel nanoparticles of tunable shape have been synthesized in THF, in the presence of hexadecylamine (HDA) or trioctylphosphineoxide (TOPO), in mild conditions and characterized by HREM and SQUID measurements. The formation of nanorods is promoted by a high amine content in the reaction medium. In contrast to what is observed for TOPO-protected nickel particles, the saturation magnetization of HDA-capped nanoparticles is comparable to that of bulk nickel, which demonstrates that the coordination of an amine ligand does not alter the magnetic properties of nickel.

Decomposition of the organometallic precursor [Sn(NMe 2 ) 2 ] 2 in a controlled water/anisol mixture leads to the formation of monodisperse nanocomposite particles of Sn/SnO x . Full oxidation of the particles into SnO 2 occurs at 600°C without size or morphology change. These particles can be deposited onto silicon nitride covered microelectronic platforms and used as sensitive layers of gas sensors. Doping of the sensors with palladium can be achieved either by co-decomposition of organometallic precursors (doping in volume) or by deposition of palladium on preformed SnO 2 nanoparticles (doping in surface). The doped sensors display an unusually high sensitivity for CO sensing.

In this study results are reported on the transport and decomposition behavior of a trifluoroacetato complex of formula Ni(dmen) 2 (tfa) 2 , in view of its use as a precursor for the MOCVD of Ni. It is shown that Ni(dmen) 2 (tfa) 2 can be sublimed up to 190 °C without decomposition with, however, a relatively low partial pressure MOCVD of Ni films from this precursor on silicon and on silica are also reported, performed at temperatures varying between 275°C and 350°C. It was found that the process is kinetically controlled. Films are crystalline, present a granular morphology and, depending on operating conditions, are composed of Ni, of metastable nickel carbide Ni 3 C or of mixtures thereof. The carbon content decreases with decreasing deposition temperature and with increasing hydrogen flow rate. It is also higher in the first deposited layers, revealing a different decomposition mechanism of the precursor on an inert relatively to a metallic surface. Although processing conditions have not been optimized, MOCVD of Ni films from this family of complexes appears promising, However, modifications of the structure of Ni(dmen) 2 (tfa) 2 are necessary to increase its volatility and consequently the growth rate of the films.

A solvent-free synthesis and the properties of esters of starch from different sources (maize, waxy maize, Eurylon 7, potato, wheat, rice, amylose, and amylopectin) and higher fatty acids are described. Higher fatty acid esters (C 8 -C 18 ) of potato starch were synthesized by chemical gelatinization using formic acid, followed by treatment with fatty acid chlorides. Esterification was readily carried out at 105 °C and a reaction time of 40 min. Formic acid permits esterification of starch by long-chain acid chlorides with minimum degradation. The results indicated that the degree of substitution of the starch esters diminishes with increase in fatty acid chain length. All starch esters have a hydrophobic character which rises with length of the fatty side chain. X-ray and Differential Scanning Calorimetry (DSC) showed that the fatty acid side 1 chains (C n > 16) grafted onto starch form cristallites between them. This phenomenon provokes the decrease of elongation at break for these starch esters. On the other hand, the tensile strength at break and thermal stability of fatty esters of starch increase both with a higher fatty chain grafted onto starch.

Ni(en)2(tfa)2 (1) and Ni(deen)2(tfa)2 (2) were prepared and submitted to crystal structure determinations, thermal analyses and sublimation tests. 1 proved to sublime under vacuum without decomposition, whereas 2 decomposed to give a volatile compound which has not been investigated yet. These behaviours have been related tentatively to solid state structure features. Vapour pressures against temperature have been measured for 1 and for Ni(en)(hfa)2, whose structure and thermal behaviour have been reported previously (M. Urrutigoit, C. Cecutti, F. Senocq, J.-P. Gorrichon, A. Gleizes, Inorg. Chim. Acta 248 (1996) 15). This study is part of an investigation of new nickel precursors for MOCVD.

Heterobimetallic [Ni(salen)Ln(hfa)3] species [H2salen and Hhfa being N,N′-ethylenebis(salicylideneimine) and hexa-fluoroacetylacetone respectively], where Ni(salen) acts as a neutral chelating ligand towards LnIII, form a series of isostructural compounds for Ln = YIII and any lanthanideIII cation from La to Yb. They are also isostructural with some of the [Cu(salen)Ln(hfa)3] compounds. They sublime without decomposition under vacuum which makes them potential single-source precursors in MOCVD. Sublimation, thermal behaviour, pressure and composition of the vapour phase versus temperature have been studied for the yttrium derivative, by means of thermal analyses, and mass spectrometry using a Knudsen cell. The dissociation process [Ni(salen)Y(hfa)3] = Ni(salen) + Y(hfa)3 has been thermodynamically investigated. Information on the solid-state intermolecular interactions in relation with volatility was obtained through the crystal structure determination of the gadolinium derivative. A comparative structural study of [Ni(salen)Gd(hfa)3] and [Cu(saloph)Y(hfa)3], [H2saloph is N,N′-o-phenylenebis(salicylideneimine)], allows to under-stand why the latter is less volatile than the former despite similar molecular and solid-state structures.

International audience; The present paper is a paradigm for the one-step formation of complex intermetallic coatings by chemical vapor deposition. It genuinely addresses the challenge of depositing an intermetallic coating with comparable contents of Cu and Al. Depending on processing conditions, a pure γ-Al4Cu9 and multi-phase Al-Cu films are grown with wetting properties of the former being similar to its bulk counterpart. The deposition process and its parametric investigation are detailed. Two metalorganic precursors are used taking into account their transport and chemical properties, and deposition temperature ranges. On line and ex situ characterizations enlighten the competition which occurs at the growing surface between molecular fragments, and which limits growth rates. Notably, introducing a partial pressure of hydrogen gas during deposition reduces Al growth rate from dimethylethylamine alane (DMEAA), by displacing the hydrogen desorption equilibrium. This Al partial growth rate decrease is not sufficient to achieve a Cu/Al atomic ratio that is high enough for the formation of intermetallics with close Al and Cu compositions. A fivefold increase of the flux of the gaseous copper(I) cyclopentadienyl triethylphosphine CpCuPEt3, whereas the DMEAA flux remains constant, results in the targeted Al/Cu atomic ratio equal to 44/56. Nevertheless, the global growth rate is rendered extremely low by the deposition inhibition caused by a massive phosphine adsorption (-PEt3). Despite these limitations, the results pave the way towards the conformal coating of complex surface geometries by such intermetallic compounds.

International audience; The present work is an evaluation of the most efficient pretreatments that are used in the field ofmetallization of poly-epoxies. In particular, we treat the case of MOCVD metallization with the constraints of limiting preparation steps and non-null, though limited thermal budget, and obtaining smooth, adherent, and highly conductive Cu coatings. Several results are presented after applying ex or in situ mechanical and chemical treatments. For the first time, transmission electron microscopy investigations illustrate the effect on the coating of H2O vapor addition during the first steps of the deposition process. In an originalmanner, we showthat the enhancement of surface reactivity displaces the center of mass of the deposit towards the gas entry in the hot-wall reactor. Additionally,with the particularity of the hot-wall configuration,we show that differences in the deposition conditions along the reactor locally place the deposition in different regimes, i.e. diffusional or kinetic, with a strong effect on the coating microstructure and properties. Therefore, for both controlling the film properties and tuning the MOCVD reactor and the processing conditions,surface reactivity must be considered, in addition to the classical macroscopic processing parameters.

International audience; This study is devoted to the physicochemical and mineralogical characterizations of palygorskite from Marrakech High Atlas, Morocco. The raw clay and its Na?-saturated\ 2 lm fraction were characterized using chemical, structural, and thermal analytical techniques. Measurements of specific surface area and porous volume are reported. The clay fraction was found to be made up of 95 %of palygorskite and 5 % of sepiolite. An original feature of this palygorskite is its deficiency in zeolitic H2O. The half-cell structural formula of its dehydrated form was determined on the basis of 21 oxygens to be (Si7.92Al0.08)(Mg2.15Al1.4Fe0.4Ti0.05h1)(Ca0.03 Na0.08K0.04)O21, while the hydrated form could be formulated as (Si7.97Al0.03)(Mg2.17Al1.46Fe0.40Ti0.05)(Ca0.03Na0.07K0,03) O20.18(OH)1.94(OH2)3.8812.43H2O. These formulas showthat the (Al3??Fe3?)/Mg2? ratio is around 0.84, revealing a pronounced dioctahedral character. Further, inside its octahedral sheet, it was determined that the inner M1 sites are occupied by vacancies, whereas the M2 sites are shared between 90 % of trivalent cations (78 % for Al3? and 22 % for Fe3?), 7.5 % of Mg2+, and 2.5 % of Ti4+, all of them linked to 1.94 of structural hydroxyls. The two remaining Mg2+ by half-cell occupy edge M3 sites and are coordinated to 3.88 molecules of OH2. Channels of this palygorskite are deficient in zeolitic H2O since they contain only 2.43 H2O molecules.A correlation was found between these results and the observation of very intense and well-resolved FTIR bands arising from dioctahedral domains (mainly Al2OH, Fe2OH, and AlFeOH) along with very small responses from a trioctahedral domain (Mg3OH). Accordingly, a schematic representation of the composition of the octahedral sheet was proposed. The cation exchange capacity, specific surface area, and total pore volume were also assessed to be ca. 21.2 meq/100 g, 116 m2/g, and 0.458 cm3/g, respectively.

There is interest in exploiting and developing natural resources, particularly deposits of natural clays. Senegal has several clay mineral deposits for which chemical and mineralogical compositions have been little studied. Some of these natural materials are nowadays used in pottery and ceramics. To extend applications, a better basic knowledge is required and, for this objective, the raw clay and separated 29Si and 27Al MAS-NMR spectra show the presence of silicon atoms linked to three other silicon atoms via an oxygen atom and six coordinated Al atoms. Significant increases in the specific surface area and cation exchange capacity were observed on purification, reaching a maximum of about 73.2 m2g–1 and 9.5 meq/100 g for the separated fine clay fraction while the values for the raw material were around 28.9 m2g–1 and 7.3 meq/100 g.

International audience; Sequential processing of aluminum and copper followed by reactive diffusion annealing is used as a paradigm for the metalorganic chemical vapour deposition (MOCVD) of coatings containing intermetallic alloys. Dimethylethylamine alane and copper N,N'-di-isopropylacetamidinate are used as aluminum and copper precursors, respectively. Deposition is performed on steel and silica substrates at 1.33 kPa and 493–513 K. Different overall compositions in the entire range of the Al–Cu phase diagram are obtained by varying the relative thickness of the two elemental layers while maintaining the overall thickness of the coating close to 1 µm. As-deposited films present a rough morphology attributed to the difficulty of copper to nucleate on aluminum. Post-deposition annealing is monitored by in situ X-ray diffraction, and allows smoothening the microstructure and identifying conditions leading to several Al–Cu phases. Our results establish a proof of principle following which MOCVD of metallic alloys is feasible, and are expected to extend the materials pool for numerous applications, with innovative thin film processing on, and surface properties of complex in shape parts.

International audience; The mechanism of formation of detrital, beidellite-rich clay occurring in the Agadir basin (Morocco) is well documented, but its detailed characterization is incomplete which limits its application. The aim of the present study was to provide further details of the mineralogical and physico-chemical characteristics of this clay. Bulk raw clay and its Na+-saturated

This study deals with the synthesis of TiO2 supported Moroccan palygorskite fibers and their use as photocatalyst for the removal of Orange G pollutant from wastewater. The TiO2-palygorskite nanocomposite synthesis was accomplished according to a colloidal route involving a cationic surfactant as template (hexadecyltrimethylammonium bromide) assuring hence organophilic environment for the formation of TiO2 nanoparticles. The clay minerals samples were characterized before and after functionalization with TiO2. Anatase crystallizes above ca. 450 °C and remarkably remains stable up to 900 °C. In contrast, pure TiO2 xerogel obtained from titanium tetraisopropoxide (TTIP) showed before calcination a nanocrystalline structure of anatase. By increasing the temperature, anatase readily transforms into rutile beyond 600 °C. The remarkable stability at high temperature of anatase particles immobilized onto palygorskite microfibers was due to the hindrance of particles growth by sintering. Homogeneous monodisperse distribution of anatase particles with an average size of 8 nm was found by TEM and XRD onto palygorskite fibers. This anatase particle size remains below the nucleus critical size (ca. 11 nm) required for anatase–rutile transition. The TiO2 supported palygorskite sample annealed in air at 600 °C for 1 h exhibits the highest photocatalytic activity towards the degradation of Orange G compared to nanocomposite samples prepared under different conditions as well as pure TiO2 powders obtained from the xerogel route or commercially available as Degussa P25.

International audience; Iron bis(N,N-diisopropylacetamidinate) [Fe2(µ-iPr-MeAMD)2(2-iPr-MeAMD)2] and iron bis(N,N-di-tert-butylacetamidinate) [Fe(tBu-MeAMD)2] were used as precursors for the metallorganic chemical vapor deposition (MOCVD) of iron-containing compounds including pure iron, iron carbides, Fe3C and Fe4C, and iron nitrides Fe4C. Their decomposition mechanism involves hydrogen migration followed by dissociation of the Fe–N bond and the release of free hydrogenated ligand (HL) and radicals. Surface intermediates are either released or decomposed on the surface providing Fe–N or Fe–C bonds. MOCVD experiments were run at 10 Torr, in the temperature ranges of 350–450°C with Fe2(µ−iPr-MeAMD)2(2-iPr-MeAMD)2 and 280–350°C with Fe(tBu-MeAMD)2. Films prepared from Fe2(µ−iPr-MeAMD)2(2-iPr-MeAMD)2 contain Fe, Fe3C, and Fe4C. Those prepared from Fe(tBu-MeAMD)2 contain Fe, Fe3C, and also Fe4C or Fe4N, depending on the temperature and hydrogen to precursor ratio (H/P) in the input gas. The room-temperature coercive field of films processed from Fe(tBu-MeAMD)2 is 3 times higher than that of the high temperature processed Fe4N films.

Simply decomposing InCp at room temperature in the presence of hexadecylamine leads to the formation of indium nanowires with a crystalline bct structure, a mean diameter of about 200 nm, and lengths in the micrometer range. The method can be extended to the preparation of In3 Sn nanowires of about 100 nm in diameter (a transmission electron micrograph is shown in the picture). Cp=C5 H5 (-) .

This study aims at establishing a correlation between the electrical charge of Moroccan stevensite particles and ionic dyes adsorption. The electrophoretic mobility, (Ue), of the stevensite particles in water, was measured at pH 2.5–12 by microelectrophoresis. At pH between 2.5 and 8, Ue remained constant (Ue = − 1.6 10− 8 m2/(V s)), as resulting from the permanent charge of the clay mineral planar surfaces. At pH > 8, the magnitude of electrophoretic mobility increased (Ue = − 2.7 10− 8 m2/(V s)) due to the deprotonation of silanol groups on the surfaces. The anionic Orange G adsorption at the clay mineral–water interface was negligible whereas the methylene blue cations were strongly adsorbed due to the electrostatic attraction.

The structures of the oxide scale formed on a lamellar (gþ a2) Ti46Al8Nb alloy after heat-treatment in air at 700 C for 50 and 1000 h have been compared. Though the outer scale is thicker after 1000 h, both oxide scales are similarly layered with an outer aluminium-rich layer. The main difference is that the aluminium-rich oxide is amorphous after 50 h while it becomes cubic gamma alumina after 1000 h. After 50 h, the presence of TiN was detected at the interface between the scale and the base metal. After 1000 h of oxidation, the subscale region is divided into two clearly separated zones differing by their composition, with a thick TiN layer close to the oxide scale. From these observations, it appears that the development of the oxide scale at 700 C is similar to the scheme proposed in the literature for short times at higher temperatures, with the initial formation of a transient aluminium-rich oxide layer, which here is amorphous, and precipitates of TiN at the scale/metal interface that oxidise afterwards to rutile

Seven water-soluble complexes of ruthenium and TPPTS have been prepared and characterized (TPPTS is the trisodium salt of the tri( m -sulfophenyl)phosphine):[RuCl 2 (TPPTS) 2 ] 2 1 , RuHCl(TPPTS) 3 2 , RuH(OAc)(TPPS) 3 3 , RuH 2 (TPPTS) 4 4 , RuHI(TPPTS) 3 5 , RuCl 2 (CO) 2 (TPPTS) 2 6 and [Ru(OAc)(CO) 2 (TPPTS)] 2 7 . Spectroscopic investigations have shown that in solution they have the same structures as their organosoluble analogues containing the ligand PPh 3 .