Alumina-silica nanolaminates are promising candidates for diffusion barriers on carbon and in harsh environments, providing that their conformal deposition in mild oxidative conditions can be achieved. Recently, an adaptation of rapid atomic layer deposition (Catalytic ALD), has been developed to deposit alumina-silica thin films directly on carbon surfaces, but suffers from limitations in silica chemistry control. Intermixing alumina-silica CatALD with amorphous alumina ALD diffusion barrier layers enabled to resolve issues of interfacial diffusion of silanol precursor and to maintain a regular silica growth independently of the number of deposition cycles. In this study, the generated alumina-silica nanolaminates by process combination were varied in terms of Al content, ALD layer thickness and interspersion frequency. Four alumina-silica ALD/CatALD nanolaminates benchmarked against an alumina-silica CatALD film were further investigated with regards to the formation of alumino-silicate clusters and alumina in silica migration upon annealing following different thermal routes. Thin film open pore and defect analysis by means of positron annihilation lifetime spectroscopy (PALS) showcased the role of ALD in the tuning of film nanoporosity. PALS further highlighted the relationship between the propensity in internal defects and the annealing temperature, related to concomitant events of carbide bond cleavage, silica densification, and alumina dehydration.

This study provides an in-depth analysis of the DGEBA (Diglycidyl Ether of Bisphenol A.)-DETA (Diethylenetriamine)/TA6V alloy (Titanium 90 m%, Aluminum 6 m%, Vanadium 4 m%), aiming to comprehensively describe the interactions (term encompassing all events leading to a final state, commonly used in the field of calorimetry) governing the formation of the polymer-metal interphase, thus implying a region with properties (physico-chemical or thermal) distinct from those of the bulk polymer. By integrating multiple analytical techniques - including mixing microcalorimetry, DSC, TEM/STEM/EDX, Karl Fischer titration, NIR, UV-Vis spectrophotometry, and XPS - the mechanisms involved were further elucidated. Key findings include the kinetically favorable (40 degrees C) character of the DETA/TA6V interaction versus the polyaddition process itself, as well as the crucial role of the surface chemistry and structure of the Ti-based alloy substrate in determining active site availability, and finally the quantification of water formation during the interaction. Additionally, using an analytical UV-Vis methodology with hydrogen peroxide as complexing agent, the amount of dissolved titanium ions was titrated from the Ti-based substrate surface when contacted with DETA, and checked its dependence on surface properties and microstructure. XPS results suggest that amine/Ti complexes in the final polymer/TA6V system predominantly involve N-Ti-O bonding rather than N-Ti. By shedding light on the formation of interphases involving metal-amine surface complexes and chelates, this contribution is expected to offer valuable insights for both academic and industrial users of TA6V and epoxy-based formulations.

Poly(3,4-ethylenedioxythiophene) (PEDOT) thin films are promising transparent conductors for electrodes and represent a potential alternative to indium tin oxide (ITO), which is costly and depends on critical raw materials. Optimizing PEDOT properties through careful control of processing parameters is essential for tailoring structure–property relationships in next-generation electronic devices. This study systematically investigates the influence of the oxidant-to-monomer ratio (OMR) on PEDOT films deposited by oxidative chemical vapor deposition (oCVD). The monomer 3,4-ethylenedioxythiophene (EDOT) and the oxidant antimony pentachloride (SbCl5) were used. By varying only the SbCl5/EDOT vapor-phase ratio while keeping the deposition temperature (150 °C) and film thickness (∼100 nm) constant, the effect of OMR on film morphology, molecular structure, and electrical properties was isolated. Films deposited at lower OMR values (0.1) exhibited higher electrical conductivity, attributed to reduced structural disorder. These effects were further confirmed in diode devices fabricated on both rigid and flexible substrates. PEDOT films deposited at an OMR of 0.1 produced bottom electrodes with superior electrical performance, demonstrated by higher current density and improved rectification ratio. The PEDOT films were also integrated into printed flexible zinc oxide (ZnO) Schottky diodes, achieving good rectification ratios and favorable ideality factors. Overall, the results demonstrate that the oxidant-to-monomer ratio is a critical parameter for tuning PEDOT film properties. This approach enables the fabrication of PEDOT electrodes with application-specific electronic characteristics, supporting their use as potential ITO alternatives while facilitating scalable vapor-phase processing for flexible electronic devices.

Gadolinium zirconate Gd2Zr2O7 coatings were deposited by an original route based on Direct Liquid Injection Metal Organic Chemical Vapor Deposition (DLI-MOCVD) at the relatively low temperature of 550 degrees C. By using the heteroleptic precursor [Zr(OiPr)2(tbaoac)2] combined with tris(2,2,6,6-tetramethyl-3,5-heptanedionato) gadolinium(III) [Gd(thd)3] and O2, polycrystalline coatings of Gd2Zr2O7 of columnar structure composed of the pyrochlore and fluorite phases were deposited on silicon and steel substrates. Deposition rates as high as 1 mu m/h were obtained, allowing to produce coatings reaching 25 mu m in thickness, with mean roughness lower than 1 mu m. Their thermal characterization was performed using modulated photothermal radiometry (MPTR). The coating thermal resistances appeared to be influenced by several factors, in particular the crystalline quality related with the presence of the pyrochlore and fluorite phases and the Gd/Zr ratio. The most crystallized coatings presenting the smallest column width and the highest Gd/Zr ratio provided the lowest apparent thermal conductivities, competing with the best results of the literature. This DLI-MOCVD route was developed with the objective to coat the internal surface of thermosensitive steel substrates of interest for plastic injection molding. By delaying heat transfer at the molten polymer/mold interface, such ceramic coatings could prevent premature solidification of the polymer melt, contributing to reduce part rejection. They could also be of interest for other applications needing efficient thermal barrier coatings for mild temperature use (energy, electronics, automotive, ...).

Due to the ease of supply, it has become usual for investigations of carbon fiber coatings to be carried out on high resistance carbon fibers, for intended applications at high temperatures in air. Yet, medium modulus and high modulus carbon fibers, for which carbon fiber coatings serves further purpose or are initially designed for, present significant variation in surface roughness and graphite plane stacking from their HR counterparts. As such, this study focuses on the transposition of the deposition of an environmental barrier coating onto HR, MM and HM carbon fibers, and further compares the coated fibers following a thermal cycle. To do so, a 20 nm bilayer thin film of amorphous alumina/alumina-silica was deposited using both atomic layer deposition (ALD) and catalytic ALD, and further annealed in inert atmosphere at 1100 degrees C. It was demonstrated that the HR fibers required a prior annealing to outgas the fiber core, while residual elements in the surface region of HR and HM fibers impeded the integrity of the film. Furthermore, the density of grooves at the carbon fiber surface was shown to hold substantial impact on the kinetics of crystallisation of the thin films, being determinant to the fiber surface O/C atom ratio.

Deposition of silica-based thin films on carbon microfibers has long been considered a challenge. Indeed, the oxidation-sensitive nature of carbon microfibers over 550 K and their submicron-textured surface does not bode well with the required conformity of deposition best obtained by atomic layer deposition (ALD) and the thermal oxidative conditions associated with common protocols of silica ALD. Nonetheless, the use of a catalytic ALD process allowed for the deposition of amorphous alumina–silica bilayers from 445 K using trimethylaluminium and tris(tert-pentoxy)silanol (TPS). In this study, first undertaken on flat silicon wafers to make use of optical spectroscopies, the interplay between kinetics leading to a dense silica film growth was investigated in relation to the applied operation parameters. A threshold between the film catalyzed growth and the complete outgassing of pentoxy-derived compounds from TPS was found, resulting in a deposition of equivalent growth per cycle of 1.1 nm c−1, at a common ALD rate of 0.3 nm min−1, with a flat thickness gradient. The deposition on carbon microfiber fabrics was found conformal, albeit with a thickness growth capped below 20 nm, imparted by the microfiber surface texture. STEM-EDX showed a sharp interface of the bilayer with limited carbon diffusion. The conformal and dense deposition of alumina–silica thin films on carbon microfibers holds great potential for further use as refractory oxygen barrier layers.

ZrO2 is a flagship material for the development of efficient thermal barrier coatings not only for aerospace applications but also on steel molds for plastic injection, especially to produce high quality miniaturized parts of low environmental impacts. In the present study, ZrO2 thin films of thicknesses ranging between 4 and 40 mu m were deposited on steel substrates by two key gas phase technologies, magnetron sputtering (PVD) and direct liquid injection metal organic CVD (DLI-MOCVD). The film morphology, structure and chemical composition were comparatively investigated and correlated to their heat transfer properties. All films were nearly stoichiometric and presented a columnar structure mainly formed of the monoclinic crystalline phase. The magnetron sputtering coatings were denser and smoother than the CVD ones, for which highly porous tree-like microstructures were observed without degradation of their mechanical properties. All films exhibited efficient thermal insulation properties, the thickest 40 mu m magnetron sputtering coating displaying the most significant reduction in heat transfer. The CVD films provided the highest thermal gradient decrease across their thickness, probably thanks to their higher porosity associated to a multi-angle tree-like columnar structure, both acting as scattering zones of phonons involved in heat flow diffusion. By controlling the local deposition conditions influencing the nucleation and growth mechanisms, the film porous microstructure can thus be tuned to optimize the coating thermal properties.

The hydrogen production from photo-electrocatalytic water splitting attracts extensive attention as a direct way to convert solar energy into chemical fuels. In this work, innovative photo-anodes composed of TiO2 which has a preferable growth orientation [211] conjugated with PEDOT as bi-layers are prepared by a dry process strategy, combining oxidative and metalorganic chemical vapor deposition (CVD). Pure anatase, dendritic TiO2 films of variable thickness are obtained at 500 degrees C by varying the deposition time. Increase of films thickness from 474 to 2133 nm results in morphologies that evolve from dense and angular structures to isolated and nanostructured tree-like columns with a concomitant decrease of the charge transfer resistance due to the enhancement of active facets of anatase structure. The PEDOT/TiO2 bi-layer with an overall thickness of 1350 nm and a 50 nm thick upper-PEDOT layer exhibits the highest photocurrent response (0.26 mA cm-2 at 1.8 V/RHE), a fast photocurrent response under illumination, and the best hydrogen yield up to 4.1 & mu;mol cm-2h- 1 with electronic conductivity being three order of magnitude higher than pristine TiO2.

Numerous industrial fields necessitate the development of advanced metallic materials presenting high corrosion resistance in aqueous media and being less expensive than classical high chromium steels. In the present work, amorphous zirconia, alumina and alumina/zirconia coatings have been deposited on 2 wt% chromium steel coupons using an innovative direct liquid injection metal organic chemical vapor deposition process. Scanning electron microscopy and X-ray diffraction reveal that the alumina sublayer acts as an efficient barrier against steel oxidation occurring during the amorphous zirconia deposition performed under O2 at 400 degrees C. They also show that the steel oxidation occurring concomitantly to the zirconia coating modifies the film morphology by increasing its roughness and thickness, in comparison with the same zirconia coating on alumina. The anticorrosive properties of the thin films have been studied by an immersion test of the bare and coated coupons in deionized water at 80 degrees C during 6 days and by electrochemical impedance spectroscopy in aqueous sodium chloride solution for 48 h. They reveal that, in contrast to alumina and zirconia monolayers alone, the alumina/ zirconia stack acts as a corrosion protection coating in pure water through a synergetic barrier effect against (i) oxidation by alumina and (ii) aqueous corrosion by zirconia.

Carbon microfibers make a promising candidate as textile reinforcement for high temperature composites provided that their limitation of thermal oxidation over 670 K in air is overcome. As such, this study explored the potential of atomic layer deposition (ALD) for the deposition of a substrate-nanolaminate interface layer for the design of a refractory oxygen barrier coating applied to individual carbon microfibers within a woven fabric. To this end, amorphous aluminum hydroxide was deposited at 350 K in a flow-type thermal ALD reactor operating at a pressure of 1.8 Torr, yielding a growth per cycle (GPC) of 1.0 & Aring;/cycle. The conformal aspect of the amorphous films was found to be well preserved below a thickness of 45 +/- 5 nm, above which reorganization of the substrate surface by junction of the previously deposited layers resulted in a uniform deposition. Furthermore, a minimal thickness of 20 +/- 2 nm was required to obtain self-standing films following the thermal oxidation of the carbon microfibers. Indeed, thermal treatment at 1380 K of the coated woven fabric induced multiple occurrences of neat cracks in the aluminum oxide films, attributed to the increased rigidity and mismatch between the respective thermal expansion coefficients. The dense network of nanograins of aluminum oxide was further characterized by using 4D-STEM, revealing multiple phases and orientations.

A new route to deposit alumina nanometric thin films on powders from the single source Aluminum Tri-Isopropoxide (ATI) precursor is developed using the Fluidized Bed Chemical Vapor Deposition (FBCVD) process. For this study, an easy-to-fluidize silica powder is used, as a first step to ultimately coat cohesive oxygen sensitive powders. The FBCVD process has been studied under mild temperature conditions (400–500 °C), without any containing oxygen co-reactant. The influence of the deposition parameters (temperature, total flow rate, precursor inlet molar fraction) on the process behavior (ATI vaporization rate, fluidized bed thermal profile, deposition yield) and on the coating characteristics (composition, thickness, morphology) is analysed in details. Results show that for all conditions tested, the fluidization is maintained and the bed remains almost isothermal all along the deposition experiments, allowing for a uniform coating of the whole particles of the bed. Continuous and conformal nanometric films are obtained, mainly formed of non-carbon contaminated alumina, containing however a small amount of hydroxyl bonds that could be due to air contamination. The proof of concept of using FBCVD from ATI to produce nanometric stoichiometric alumina coatings on powders is then demonstrated, opening the way for new applications.

Organic light-emitting diodes (OLEDs) are emerging technologies for potential lighting and display applications. Transparent conductive electrodes (TCEs) play a crucial role in enabling the functionality and increased performance of these particular devices. Despite their widespread use, indium tin oxide (ITO) thin films have several significant drawbacks, including material scarcity, high costs associated with both materials and fabrication processes, and limited flexibility. To address these issues, we thoroughly investigate the deposition of poly(3,4-ethylenedioxythiophene) (PEDOT) thin films as a promising alternative to ITO using a single-step and dry method named oxidative chemical vapor deposition (oCVD). The impact of increasing the substrate temperature from 110 to 190 degrees C on the film's structure and properties was revealed with an increase in the film conductivity to over 1600 S/cm at 170 degrees C and a total transmittance of 97% in the visible range. This increase was attributed to a change in the molecular structure of the conjugated polymer from benzoid to quinoid as revealed by Raman and FTIR measurements. The XPS results demonstrated an increase in the doping ratio with Cl-containing species and a reduction of impurities. GIXRD, HR-TEM, and AFM measurements indicated a smooth surface and a highly face-on orientation for all temperatures. The optimized TCE layers were successfully integrated into deep blue OLED devices emitting at 436 nm with stable color Commission Internationale de l'Energie (CIE) coordinates of (0.15, 0.08) under variation of the applied current. A satisfactory performance (72.1 cd/m(2) and 0.86 W/srm(2) at 10 mA cm(-2)) and an external quantum efficiency (EQE) of 1.04% were achieved. These results are quite promising, as OLEDs based on PEDOT as a TCE have demonstrated slightly better output performance in terms of luminance and radiance, with an increase in EQE by a factor of 1.7, compared to the reference device based on ITO.

Glass packaging of novel medicinal molecules is challenged by hydrolysis of the glass network from an interaction with the stored drug, likely to result in leaching of constituent elements of the glass into the solution. We have succeeded in applying chemical-vapor-deposited silicon oxynitride coatings from a highly reactive trisilylamine derivative molecule as a precursor, at a temperature below 580 degrees C, opening up the possibility utilizing such coatings on glass surfaces. We demonstrate that such silicon oxynitride coatings applied on the internal surface of pharmaceutical vials prevent degradation, providing chemical inertness and withstanding severe screening conditions of the United States Pharmacopeia USP <1660> chapter. Fine structural determination and atomistic modeling of the Si-O-N network of the films confirm the nitrogen substitution of oxygen and densification of the silicate network through the addition of the former. The achieved barrier properties and excellent performance of these coatings pave the way toward sustainable packaging with improved product shelf life, transferable to multiple applications of surface coatings.

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), O-2, and NH3, using conveniently scalable atmospheric pressure chemical vapor deposition (CVD) at moderate temperature (600-650 degrees C). A suite of characterization techniques including spectroscopic ellipsometry (SE), Fourier-transform infrared spectroscopy (FT-IR), ion beam analyses (IBA), nanoindentation, nanoscratch, X-ray 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.

An apparent kinetic model is developed for a novel chemical vapor deposition (CVD) process of silicon oxynitride (SiOxNy) films from tris(dimethylsilyl)amine (TDMSA) and O-2, operating at moderate temperature (600-650 degrees 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 gas and 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 carbon containing 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 (R) FLUENT (R) computational fluid dynamics (CFD) code. Upon validation, the model allows for the successful prediction of local deposition rates and SiOxNy 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 multi component thin films, favoring their implementation in original applications.