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Antibacterial coatings are becoming increasingly attractive for application in the field of biomaterials. In this framework, we developed polymer coating zirconia with antibacterial activity using the "grafting from" methodology. First, 1-(4-vinylbenzyl)-3-butylimidazolium chloride monomer was synthesized. Then, the surface modification of zirconia substrates was performed with this monomer via surface-initiated photo atom transfer radical polymerization for antibacterial activity. X-ray photoelectron spectroscopy, ellipsometry, static contact angle measurements, and an atomic force microscope were used to characterize the films for each step of the surface modification. The results revealed that cationic polymers could be successfully deposited on the zirconia surfaces, and the thickness of the grafted layer steadily increased with polymerization time. Finally, the antibacterial adhesion test was used to evaluate the antibacterial activity of the modified zirconia substrates, and we successfully showed the antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa strains. [ABSTRACT FROM AUTHOR]

In the search of low cost and more efficient electronic devices, here the properties of SrVO3 transparent conductor oxide (TCO) thin film are investigated, both visible‐range optically transparent and highly conductive, it stands as a promising candidate to substitute the standard indium‐tin‐oxide (ITO) in applications. Its surface stability under water (both liquid and vapor) and other gaseous atmospheres is especially addressed. Through the use of spectroscopy characterizations, X‐ray photoemission and operando X‐ray absorption measurements, the formation of a thin Sr‐rich V5+ layer located at the surface of the polycrystalline SrVO3 film with aging is observed, and for the first time how it can be removed from the surface by solvating in water atmosphere. The surface recovery is associated to an etching process, here spectroscopically characterized in operando conditions, allowing to follow the stoichiometric modification under reaction. Once exposed in oxygen atmosphere, the Sr‐rich V5+ layer forms again. The findings improve the understanding of aging effects in perovskite oxides, allowing for the development of functionalized films in which it is possible to control or to avoid an insulating surface layer. This constitutes an important step towards the large‐scale use of V‐based TCOs, with possible implementations in oxide‐based electronics. [ABSTRACT FROM AUTHOR]

Although vanadium compounds are well recognized for their ability to change from insulator to metal, they may also be used therapeutically to address significant medical issues. In this study, we used vanadium oxide thin films synthesized by the pulsed laser deposition (PLD) technique to examine human stem cells generated from bone marrow. According to x-ray reflectivity (XRR) measurements, the films' thickness ranged from 6 to 26 nm. The water contact angle method has been employed to probe the surface energy and wettability of the films, which influence the cell behavior significantly. We also used a variety of techniques, such as differentiation staining, phase contrast microscopy, and real-time reverse transcription-polymerase chain reaction (RT-PCR), to examine the growth, adhesion, proliferation, and differentiation of human bone marrow mesenchymal stem cells (hBMMSCs) on these oxide films over time. Our results indicated that vanadium oxide films alter hBMMSCs adhesion and growth and affect their differentiation. The application of VOx films in biological and medical materials, as well as future research on cells, is all made possible by these findings, which also improve our understanding of the biological actions of vanadium compounds. [ABSTRACT FROM AUTHOR]

Indium‐tin‐oxide (ITO) is a widely employed transparent conducting oxide (TCO), but the indium scarcity and price encourage developing some alternatives. The correlated metals CaVO3 and SrVO3 have been recently identified as new TCOs with functional properties being comparable to ITO. However, their technological potential is limited by the critical requirement of a perovskite structure of the film, impossible to achieve via direct growth on substrates commonly used for applications. In this article, the authors tackle this limitation by demonstrating the crystalline growth of vanadate TCOs on glass at temperatures below 600 °C, with the help of 2D nanosheets as transparent seed layers. The functional properties do not suffer from the textured structure of the films, as confirmed by an in‐depth spectroscopic ellipsometry study, allowing for an industrially viable approach to integrate vanadate TCOs on virtually any surface and to exploit their promising performances as a new generation TCO. [ABSTRACT FROM AUTHOR]

Since SrVO3 (SVO) can be used as a highly conductive material for perovskite heterostructures, the control of surface morphology and chemistry of such thin‐films are essential. Using pulsed laser deposition, two distinct topographies can be produced. Thus, by tuning oxygen pressure in the growth chamber during cooling, smooth or partially covered by self‐oriented Sr3V2O8 nanorods surfaces can be grown. This study manages to correlate the two typical topographies, revealed by atomic force microscopy (AFM), with their chemical compositions obtained by X‐ray photoelectron spectroscopy (XPS). At first, a model describes their initial surface chemistry through the Sr/V cationic ratio and the (Sr+V)/Oox ratio. Furthermore, using sputter‐depth profiling, post‐thermal treatments and wet chemical etching, SVO thin‐film chemical compositions are extensively studied. We demonstrate that they are composed of stoichiometric SVO phase covered by Sr‐rich layer on top. Finally, treatment in water for 180 seconds helps to remove Sr‐rich phases. Sr3V2O8 nanorods are found selectively dissolved leaving a surface nano‐imprint. Moreover, on smooth SVO surfaces, a balanced Sr/V cationic ratio of 1.0±0.1 is obtained. These results appear very promising for SVO thin‐films surface preparation and further development as electrodes for electronic devices. [ABSTRACT FROM AUTHOR]

SrVO3 (SVO) is a model system for strongly correlated oxides and is highly promising as conductive layer in heterostructures. Therefore, the control of electronic properties and morphology are essential for the advanced applications. Here, the oxygen stability during and after the deposition is explored, as SVO film is expected to undergo different postdeposition thermal and atmosphere treatments during its integration in a heterostructure. Hence, the influence of oxygen stability on morphology and electrical properties of the metallic SrVO3 grown by pulsed laser deposition has been investigated. Films grown under vacuum (SrVO3− δ ) exhibit a very smooth surface while films grown under higher oxygen pressure roughen and present nanostructures at the surface. These nanostructures are found to be of Sr3V2O8 phase and their apparition can be controlled by the oxygen supply. Subsequent thermal treatments at different temperatures under same oxygen pressure prevent formation of the Sr3V2O8 phase, lead to the stoichiometric SrVO3, and thus improve the transport properties. In this study is shown the extreme sensitivity of SVO to oxygen and the conditions to obtain high quality smooth SVO films with improved electrical properties for electrode application. [ABSTRACT FROM AUTHOR]

We have studied the chemical and electronic properties of LaAlO3/SrVO3 (SVO) ultrathin films by combining hard x-ray photoemission spectroscopy and transport measurements. We compare single SrVO3 (SVO) ultrathin films and SrVO3 buried below a polar LaAlO3 (LAO) thin layer, both epitaxially grown on SrTiO3. While ultrathin films (4 unit cells) of SVO do show insulating behavior over the entire temperature range, the LAO/SVO interface has a resistivity minimum at 250 K. When increasing the SVO layer thickness, the minimum is observed to shift to higher temperatures, but the resistivity always stays smaller than that of comparable SVO single films. Hard x-ray photoemission spectroscopy reveals a surface or interface related V5+ component in the V 2p spectra for SVO films and LAO/SVO heterostructures, respectively, attributed to a strongly oxidized component. This chemical reconstruction is weaker in LAO/SVO heterostructures compared to single SVO films. We show that this dead layer in SVO ultrathin films has to be considered when the film thickness reaches the few unit-cells limit and propose solutions on how to prevent this detrimental effect. [ABSTRACT FROM AUTHOR]

In situ optical characterizations of metal-insulator (MI) transition have been developed in a pulsed laser deposition (PLD) chamber. It consists of associating a spectroscopic ellipsometer and an infrared camera. The first one is sensitive to modifications of the optical indexes and the second one to the emissivity changes. We focus onto the metallic LaNiO3 and the insulating SrTiO3, which present opposite electrical properties as a function of their oxygen content. Using a combinatorial synthesis approach during fabrication by PLD onto LaAlO3 substrate, we observe the evolution of the apparent temperature for different area corresponding to single LaNiO3 or SrTiO3 layers and heterostructures during reduction and reoxygenation process at constant temperature. Thus, the possibility to grow off-stochiometric samples by PLD or to reduce them by heating under high vacuum, associated to the ability of injecting controlled quantity of oxygen by pulsed valve, provide us an original tool in order to study the (MI) transition. [ABSTRACT FROM AUTHOR]

In the present work, we focus on an original study of metal-insulator transition in LaNiO (LNO) compound by IR camera mounted on a pulsed laser deposition chamber. IR thermometry is based on the measurement of the radiated energy that is a function of the surface temperature and the emissivity ( ε) of a material. Thus, at a fixed high temperature in an oxygen equilibrium state and by fixing arbitrary an emissivity value, we can follow the evolution of the 'measured temperature' linked to the change of the real emissivity value during a reduction/reoxygenation treatment. The variation of emissivity is correlated to the change in optical constants, e.g. to the conductivity measured simultaneously by an in situ spectroscopic ellipsometry. The combination of both techniques offers a convenient way to observe in situ and contactless changes from metallic to insulator behavior and vice versa. [ABSTRACT FROM AUTHOR]

Two-phase nanocomposite heteroepitaxial films with vertical microstructures hold great promise for various (multi)functional (e.g., multiferroic) electronic device applications. With the aim of creating addressable arrays, it is necessary to form spontaneously ordered structures over large areas. However, such structures have not, so far, been demonstrated. We have recently produced remarkable spontaneously ordered phase assemblies and find that these structures form concomitantly with 2-D vertical strain control, i.e., strain in the 2 phases is controlled along the vertical interface between them rather than being influenced by the substrate. In this paper, we report on our findings in the BiFeO3 and BaTiO3 ferroelectric systems. [ABSTRACT FROM AUTHOR]

Two-phase, vertical nanocomposite heteroepitaxial films hold great promise for (multi)functional device applications. In order to achieve practical devices, a number of hurdles need to be overcome, including the creation of ordered structures (and their formation on a large scale), achieving different combinations of materials and control of strain coupling between the phases. Here we demonstrate major advances on all these fronts: remarkable spontaneously ordered structures were produced in newly predicted compositions, vertical strain was proven to dominate the strain state in films above 20 nm thickness and strain manipulation was demonstrated by selection of phases with the appropriate elastic moduli. The work opens up a new avenue for strain control in relatively thick films and also promises new forms of ordered nanostructures for multifunctional applications. [ABSTRACT FROM AUTHOR]

This article reports on the magnetism of continuous and patterned bismuth iron garnet (Bi3Fe5O12 or BIG) thin films for magnetophotonic crystal (MPC) applications. The exact knowledge of the magnetic properties is crucial for the design of fully functional MPC. BIG thin films were grown on several types of isostructural substrates by pulsed laser deposition. The growth conditions and bismuth transfer were optimized to obtain good quality magneto-optically active films compatible with nanostructuring process. MPC were successfully fabricated from BIG/GGG(001) films with low roughness and high Faraday rotation. Magnetic characteristics (magnetization, anisotropy, magnetic domains, magnetization reversal) of the continuous BIG films and MPC were extensively studied and compared to the results of the micromagnetic simulations performed for MPC with different anisotropy. The present study shows that the fabrication of the MPC structure lowers the magnetocrystalline and uniaxial in-plane anisotropies and induces a partial out-of-plane magnetization. External field smaller than 2000 G is sufficient to ensure the out-of-plane saturation of magnetization for optimum device operation, in agreement with micromagnetic calculations. The experimentally determined magnetic properties of MPC are fully compatible with the device operation. [ABSTRACT FROM AUTHOR]

The vanadate SrVO3 is a transparent conductor perovskite with optical and electrical properties competing with those of the most‐used indium tin oxide material. Although its charge density is comparable to that of metals, SrVO3 shows a plasma frequency below the visible range due to strong electronic correlations characterizing the electronic transport in this material and enhancing the effective mass. Therefore, the well‐known interplay between the structure and the electronic properties of strongly correlated systems can be used in such transparent conductor to tune the optical properties, as the plasma frequency also depends on the effective mass. In this study, SrVO3 films are grown by pulsed laser deposition onto different lattice mismatched perovskite substrates such as SrTiO3, LaAlO3, and (LaAlO3)0.3(Sr2TaAlO6)0.7 at different growth temperatures. The structural, electronic, and optical properties are analyzed, illustrating the influence of the strain on the structure of the films and on a shift of the plasma frequency. The electronic correlations in this new group of transparent conducting oxides can be therefore used as a supplementary lever for the tuning of the functional properties. SrVO3 thins films are grown by pulsed laser deposition onto SrTiO3, LaAlO3, and (LaAlO3)0.3(Sr2TaAlO6)0.7. Both optical and electrical properties of the films are investigated and demonstrate that such strongly correlated system is competing with the indium tin oxide as new transparent conducting oxide. The plasma frequency of the films depends on the substrate and can be easily tuned toward the infrared region. [ABSTRACT FROM AUTHOR]