As the slowest species, the diffusion of silicon controls the deformation of olivine and plays a crucial role in Earth dynamics. The diffusion of silicon in olivine remains controversial as literature diffusivities spread over several orders of magnitude. Furthermore, the extent of enhancement by hydrogen, observed in both olivine and forsterite (iron-free olivine) remains unclear. We performed experiments of volume diffusion of silicon in dry forsterite. We conclude to a significant effect of hydrogen as diffusivities from previous hydrous experiments with up to 1000 wt. ppm H2O are up to 3 log unit higher than our anhydrous experiments. We analyze our results together with literature data for both forsterite and olivine, and provide laws for silicon volume diffusion in olivine (Ol) D_Si^Ol = ( 10^ - 10.50 + 10^ - 8.78 C_H_2 O^0.42)e^ - 316000 + 1460 P/8.314 T , and in forsterite (Fo) D_Si^Fo = ( 10^ - 11.64 + 10^ - 9.38 C_H_2 O^0.42)e^ - 316000 + 1460 P/8.314 T , where the diffusivity DSi is in m2/s, temperature T in K, pressure P in GPa and hydrogen concentration C_H_2 O in wt. ppm H2O. Hydrogen starts enhancing the diffusion of silicon in olivine at very low concentrations. Diffusivity is already increased by 1.7 log unit at 1 wt. ppm H2O. Consequently, the diffusion of silicon virtually always occurs in the hydrous regime in mantle olivine. However, variable mantle hydration is not expected to result in drastic variation in diffusivity. A change in olivine hydrogen concentration by a factor 10 modifies diffusivity by a factor 2.6 only. As the deformation mechanism of olivine that should prevail in the asthenosphere, i.e. dislocation creep, depends linearly on silicon diffusivity, olivine viscosity will primarily relate to temperature rather than hydration.

Electronic correlations and chemical disorder play a pivotal role in the emerging class of perovskite transparent conducting oxides (TCOs). These materials exhibit charge carrier densities typical of metals, yet achieve optical transparency through the enhanced effective mass, which shifts the plasma frequency beyond the visible range. In this study, we systematically tune the electronic and structural disorder of epitaxial thin films on (001) substrates by annealing treatments. The controlled variations modulate the electronic correlations, leading to gradual changes in optical transparency and electrical resistivity. By analyzing these modifications of the functional properties, we elucidate the role of electronic correlations and disorder in , and propose the design strategies for optimizing the TCO performance of the perovskite oxides.

PrNiO3 and Pr0.8Sr0.2NiO3 epitaxial thin films were deposited by pulsed laser deposition (PLD) on different substrates and studied for Hall effect and resistivity behavior. Conductive behavior is observed in the doped composition, and a normal Hall effect allows to determine charge carrier’s density and mobility. The doped compositions show a high concentration of charge carriers (≈1023 cm−3 at 300 K), and it appears that they can be controlled by the strains. Sr doping enhances the transport properties, leading to a transition from semiconducting to metallic behavior. The impact of the reduction process on charge carrier concentration and mobility is also studied.

In the growing field of low-cost electronics, the epitaxy of complex oxide thin films on a Si substrate requires significant technical means. Therefore, a large attention is paid to the release of a freestanding oxide of interest from its deposition support which is then placed onto a low-cost substrate, via the etching of an intermediate sacrificial layer. The use of a sacrificial layer offers several advantages since the flexible polymer exploited for the transfer can also be fully utilized to design a flexible heterostructure. For green technology, more and more research investigations are being undertaken on these sacrificial layers etched by water. While Sr3Al2O6 and SrVO3 are archetypical examples, the need to find new materials with different lattice parameters and symmetry is critical to reach the epitaxy of numerous materials of interest. In this study, the possibilities of an A-site cationic variation in AVO3 with A = Sr and/or Ca thin films are highlighted to expand the water-soluble material's family reaching the smallest lattice parameter ever presented up to now. In addition to bring various compounds with different ageing properties to the literature, optical spectrophotometry operando characterizations to follow the chemical etching of the sacrificial layers in real-time are exploited.

RE 0.8 Sr 0.2 NiO 3 epitaxial thin films (with RE = Pr or Nd) are grown by pulsed laser deposition on SrTiO 3 and (LaAlO 3 ) 0,3 (Sr 2 TaAlO 6 ) 0,7 (001) (LSAT). Thin films are reduced in RE 0.8 Sr 0.2 NiO 2 and studied in transport properties. In preliminary transport measurements, the transport behavior is close to superconductivity. A study of the chemical composition of the perovskite phase as well as the infinite phase is carried out to determine the impact of the reduction process. In particular, a reduction in the cationic ratio is visible after the completion of the topotactic reduction. In the second part, the study of the impact of strains on the homogeneity of thin films after reduction is carried out. The control of homogeneity by modulating strains depending on the substrate is discussed.

In orthorhombic perovskite oxides (RMO_3), substituting R^3+ rare-earth cations tailors the spin, orbital, and charge degrees of freedom of the central M^3+ transition metal cations through lattice distortions. In turn, these modify also the surrounding environment of R^3+. When both R^3+ and M^3+ exhibit magnetic properties, phenomena such as spin reorientation and magnetization reversal can occur. In fact, the underlying exchange interactions between M-3d spins and R-4f magnetic moments enrich the multifunctional character of RMO_3, particularly when combined with structural distortions. They play a crucial role in achieving appealing properties such as robust magnetoelectricity with non-collinear magnetic orders. Here, we explore the exchange coupling in epitaxial PrVO_3 thin films, selectively probing the magnetism of cation sublattices, and uncovering simultaneous V^3+ 3d spin reorientation and Pr^3+ 4f magnetization reversal using spectroscopy techniques. By strain engineering, we manipulate the lattice distortions to rationalize their role in coupling 3d spins and 4f magnetic moments. Theorectical calculations show that octahedral rotations and Jahn-Teller distortions act as tuning mechanisms, promoting competition between orbital and spin orders. The observed coupling between magnetic cations and lattice distortions can be extended to other orthorhombic RMO_3 systems, advancing the understanding of controlling spins in engineered perovskite heterostructures and superlattices.

Nanosheets (NS) provide an innovative method for growing perovskite thin films on diverse substrates like glass and silicon, serving as germination seeds and offering a cost-effective alternative to expensive monocrystalline substrates. According to the NS transfer process onto the substrate, more than 85-90 % of the substrate is covered. However, a small fraction of the perovskite film grows directly on the substrate. This raises several questions: Is the perovskite film grown on glass conductive? How does the NS network influence electrical properties at macroscopic and submicron scales? To address these questions, we investigated the impact of thickness on the transport properties of transparent conductive SrVO3 vanadate deposited on glass coated with [Ca2Nb3O10]- nanosheets (CNO NS). Macroscopic measurements revealed significant degradation of transport properties at thicknesses below 15 nm. In-plane local electrical properties were examined using Scanning Spreading Resistance Microscopy. Our findings indicate that local transport remains nearly constant when SrVO3 is grown on NS, while a strong thickness dependence is observed when SrVO3 is directly deposited on glass. These results contribute to a better understanding of the growth process, the integration of functional oxides on NS and open new perspectives for tuning the properties of vanadate films as transparent electrodes.

Correlated transparent conducting oxides (TCOs) have gained great attention, because of their unique combination of transparency and metallic character. SrVO3 (SVO) was identified as a high-performance TCO in the visible range. Few studies have investigated band structure engineering through chemical doping to enhance the optical properties of SVO. Here, we use two different strategies by exploiting the band-filling and width of the bands derived from Vanadium to tune the screened plasma frequency omega(p)* and the interband transition Ep-d energy, corresponding to the optical transparency window edges. For control of the band-filling strategy, it is found that Titanium doped SVO has a wide transparency window, but such a composition does not maintain the high electrical conductivity required for TCO applications. Concerning the bandwidth strategy, the doping of SrVO3 by Calcium shows that omega(p)* remains located in the IR range (1.12 eV), while Ep-d is blue-shifted into the UV region (3.43 eV) due to reinforced electronic correlations. By an appropriate choice of dopant, we successfully increased the size of the transparency window by around 11% from 1.94 eV (SVO) to 2.30 eV (Calcium-doped SVO), while retaining high conductivity of around 2.30 x 10(4) (Scm(-1)) and high charge carrier density of 2.93 x 10(22) cm(-3).

LaVO3 (LVO) is particularly interesting due to its optical band gap of around 1.1 eV, which is close to the one of silicon (1.12 eV) and can be an interesting light-absorbing material for photovoltaic and photocatalytic devices. In this context, we investigated the optical and transport properties of LaVO3 grown on SrTiO3 (STO) heterostructures under various growth conditions. The study of the optical properties shows significant variation in optical absorption with oxygen partial pressure during the deposition. Moreover, from the electrical point of view, the LaVO3/SrTiO3 deposited at low oxygen pressure reveals a metallic behavior with high mobility conduction. However, those grown at high oxygen pressure turn into an insulator showing a metal–insulator transition. Interestingly, the optical measurements combined with electrical sheet resistance confirm that the metallic behavior originates from the diffusion of oxygen vacancies within the SrTiO3 substrate during the deposition process of LaVO3 layers. These results open fascinating prospects to use LaVO3 as an efficient optical absorber for solar irradiance, whereas, the SrTiO3 substrate could be integrated as a bottom electrode to facilitate the collection of charge carriers. As a result, LaVO3/SrTiO3 system shows promising properties and might be potentially interesting for future integration in photovoltaic and photocatalytic applications.

Accurate structure analysis of epitaxial perovskite thin films is a fundamental step towards the ability to tune their physical properties as desired. Precession-assisted electron diffraction tomography (PEDT) has proven to be an effective technique for performing ab initio structure solutions and refinements for this class of materials. As the film thickness or the region of interest (ROI) decrease in size, the capacity to collect PEDT data with smaller electron beams is a key parameter and ROI tracking becomes a major issue. To circumvent this problem, we considered here an alternative approach to acquiring data by combining PEDT with a scan over an area, extracting the intensities collected at different positions and using them to perform accurate structure refinements. As a proof of concept, a Scanning Precession Electron Tomography (SPET) experiment is performed on a 35 nm thick perovskite PrVO3(PVO) film deposited on a SrTiO3 (STO) substrate. This way, it was possible to detect small changes in the PVO structure along the film thickness, from the variation in unit cell parameters to atomic positions. We believe that SPET has the potential to become the standard procedure for the accurate structure analysis of ROIs as small as 10 nm.

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.

SrVO3 (SVO) is a prospective candidate to replace the conventional indium tin oxide (ITO) among the new generation of transparent conducting oxide (TCO) materials. In this study, the structural, electrical, and optical properties of SVO thin films, both epitaxial and polycrystalline, are determined during and after heat treatments in the 150-250 °C range and under ambient environment in order to explore the chemical stability of this material. The use of these relatively low temperatures speeds up the natural aging of the films and allows following the evolution of their related properties. The combination of techniques rather sensitive to the film surface and of techniques sampling the film volume will emphasize the presence of a surface oxidation evolving in time at low annealing temperatures, whereas the perovskite phase is destroyed throughout the film for treatments above 200 °C. The present study is designed to understand the thermal degradation and long-term stability issues of vanadate-based TCOs and to identify technologically viable solutions for the application of this group as new TCOs.

Bacteria are commonly found in various environmental sources, such as soil and water. Among the different bacterial species, Pseudomonas aeruginosa is particularly known for causing infections in humans and can easily colonize surfaces. To address this issue, one approach is to modify the surface with antibacterial coatings. Thus, here, we investigate the effectiveness of Cu–Ti oxide coatings by fabricating Cu1−xTixO2 (0.25 < x < 0.75) thin films on glass substrates using the pulsed laser deposition technique. Microstructural analysis revealed that the films were amorphous and exhibited a smooth surface. In addition, the contact angle measurements demonstrated high hydrophilicity, as indicated by values below 90°. Subsequently, we examined the biofilm formation of Pseudomonas aeruginosa bacteria on both Cu1−xTixO2 coated and uncoated glass surfaces. The results revealed a 20% reduction in bacterial growth on Cu0.75Ti0.25O2-coated samples, as determined by calculating the biomass of the biofilm. These findings were further discussed in relation to the copper content present on the surface of the coating. Ultimately, the results contribute to our understanding of bacterial development on various surfaces. Consequently, this research may have practical implications for enhancing the antibacterial properties, preventing bacterial infections associated with different materials and surfaces, and improving implant performance.

Bacteria is commonly found in the environment, like soil and water. Among the different species, Pseudomonas aeruginosa is the one that most commonly causes infections in humans and can be present on surfaces. To limit its development, the modification of the surface with antibacterial layers is one way to address this problem. Here, we test the bioactivity of Cu-Ti oxides by preparing a series of Cu1−xTixO2 (0.25 < x < 0.75) hin films on glass substrates using the pulsed laser deposition (PLD) technique. The microstructure analysis reveals the films are amorphous and smooth. Also, the contact angle is found less than 90◦ indicating a high hydrophilic nature. We further tested the biofilm formation of Pseudomonas aeruginosa bacteria (mPAO1)on (Cu,Ti) oxides coated and uncoated glass surfaces and discovered that bacterial growth was reduced by 20% on Cu0.75Ti0.25O2-coated samples by calculating biofilm biomass. These results are discussed with the Cu content presents at the surface of the layer. Finally, these findings could be useful for understanding the development of bacteria on various surfaces.

Due to its optical and electrical characteristics, SrVO3 is a strongly correlated metal that has received extensive research in recent years. This makes it a promising transparent conducting oxide (TCO) for a variety of optoelectronic applications. The most widely used TCO at the moment, indium tin oxide, suffers from resource depletion. By analyzing and improving these interesting properties, SrVO3 might be able to take its place [1]. Unfortunately, in order to obtain SrVO3 as a crystallized phase, non-compatible with microelectronic industry thin film growth techniques must be used. Moreover, they require specific substrates for achieving the crystalline state, such as SrTiO3, LaAlO3, and (LaAlO3)0,3(Sr2TaAlO6)0,7 (LSAT) [2]. Nevertheless, recent studies made by our groups have demonstrated that crystalline SrVO3 layers may be produced on less expensive substrates such as glass or silicon substrates, with the simple use of a TiO2 buffer layer. This recent finding is covered by a global patent [3]. In the present work, we report experimental investigations on the reactively co-sputtering of SrVO3 and ZnO targets in a H-rich plasma, on Si substrates, with and without a TiO2 buffer layer, to grow transparent and conductive films. TiO2 buffer layer has been deposited on Si Substrate by Atomic Layer Deposition as reported elsewhere [4]. We looked at the effects of growth temperatures (TG) and the hydrogen rate rH (the ratio of H2 to Ar) on the thin films’ structural, electrical, and optical characteristics. XRD, high-resolution TEM, and AFM techniques were used to examine the films’ structural characteristics. The 4 probes approach, Van der Pauw measurements using a PPMS, and Hall effect measurements were used to examine the electrical properties. Finally, spectroscopic ellipsometry was used to conduct optical characterizations. The structural analysis showed that it is possible to favor the growth of crystalline SrVO3 layers on top of the TiO2 buffer layer by optimizing TG and rH (Figure 1a). In some specific conditions, a partially crystallized layer of SrVO3 was also directly deposited on a Si substrate without the use of such a buffer layer, which has never been reported in the literature and thus is encouraging for the future growth of such material on-low-cost substrate (Figure 1b). The Zn concentration in the film is only 0.15 at% because the radio-frequency (RF) power density applied to the ZnO target is much lower than the one applied to the SrVO3 target. The presence of dopants during the development process may favor the crystallization of SrVO3, which may help to explain this partial crystallization. This finding might pave the way for buffer-free complete crystallization of SrVO3 on Si substrates. When the films are grown on a TiO2 buffer layer, measurements of the physical properties have evidenced that it is possible to form thin films with optical transparency ranging from 70 to 75%, between 475 and 800 nm (Figure 1c). The thin films’ electrical resistivities at ambient temperature reach values of 1.2 × 10−3 Ohm.cm, according to electrical characterizations performed on them using the 4 probes method. Moreover, the PPMS data reveal a decrease in resistivity as a function of temperature (Figure 1d) which is the signature of semiconductor behavior. Such a feature has never been reported elsewhere and is probably due to an excess of oxygen in the layer induced 2 by the reactive growth approach. The vanadate films detailed in this paper present a sufficiently low resistivity to be used for microelectronics applications since the films produced with optimal values of rH and TG are more conductive than the undoped semiconductor films typically used as TCOs, such as ZnO and SnO2. In addition, these films feature an optical band gap, and therefore offer the opportunity to create materials with photoluminescence properties by doping them with rare earth ions for example. This is extremely promising for the design of light-emitting diodes or sensors. [1] L. Zhang et al, “Correlated metals as transparent conductors,” Nature materials, vol. 15,12 2015. [2] A. Boileau et al, “Tuning of the optical properties of the transparent conducting oxide SrVO3 by electronic correlations,” Advanced Optical Materials, vol. 7, p. 1801516, 01 2019. [3] Patent FR3113185 [4] A. Jolivet et al, “Structural, optical, and electrical properties of TiO2 thin films deposited by ALD: Impact of the substrate, the deposited thickness and the deposition temperature,” Applied Surface Science, vol. 608, p. 155214, 2023. Figure 1

In the Combinatorial Substrate Epitaxy (CSE) approach, a thin film is grown at high temperature on a polycrystalline substrate. Those substrates induce a local film epitaxy on each substrate grain and an overall polycrystalline character on the macroscopic scale. Compared to single-crystalline films, this approach provides the possibility to introduce, in a controlled way, grain boundaries providing new functionalities. Therefore, controlling the microstructure and grain size of the substrates is an important step for tuning the film properties. In this paper, a complete study of the granular growth of the standard substrate material for the deposition of perovskite thin films, SrTiO3, has been carried out with different isothermal cycles highlighting the grain growth mechanisms. From these results, we are able to predict the sintering thermal cycle necessary for targeting very precisely a desired grain size and the corresponding physical properties. Indeed, highly restraint physical properties specifications are needed for advanced electronic applications. Since a classic granular growth model was used, this approach can be generalized to the broad family of oxides.

TiO2 films were deposited by ALD on Si and glass substrates. FTIR analysis reveals an incomplete process for deposition temperatures below 160 degrees C. The transition from the amorphous to the crystallized anatase phase is observed during the variation of the deposition temperature. Films were uniform and homogeneous, with a crystallization threshold temperature depending on the substrate's nature. This delay in crystallization tem-perature was highlighted by many characterization techniques and found higher by about 50 degrees C on glass compared to Si substrate. We have also identified the determining role of the deposition temperature and the thickness in the crystallization process and we propose a growth model, independently of the substrate's nature, using different structural analyses. TiO2 refractive index (n) and extinction coefficient (k) were studied at various deposition temperature. The evolution of the TiO2 polarizability (alpha opt) with material density was determined from n values, showing a large variation of polarizability as a function of material density, in agreement and complementary with other studies. The investigation of the dielectric properties at low frequency shows that the losses and relaxation in TiO2 decrease with deposition temperature, reaching at 300 degrees C a high and frequency -independent dielectric constant, close to the one reported for polycrystalline anatase.

La0.67Sr0.33MnO3 (LSMO) thin films have been grown by pulsed laser deposition on SrTiO3 using combinatorial substrate epitaxy (CSE) approach, i.e. polycrystalline substrates with micrometer-size grains. The crystallographic domains size of those polycrystalline substrates can be controlled between 2 and 45 µm depending on the annealing temperature during synthesis. Each grain of the substrate acts as a single crystalline growth template promoting local epitaxy with a reproduction of the substrate grain structure in the thin film. Therefore, a fine-tuning of the substrate grain metrics and high crystalline quality of locally epitaxial LSMO film, allows to combine the advantages of polycrystalline, i.e. the presence of low field magnetoresistance (LFMR) and the possibility to use very thin films, with a pronounced magnetic shape anisotropy. For this, the magnetic and transport properties of the films are showing a strong influence with varying grain metrics of the substrate. High Curie temperatures, important values of the LFMR and anisotropy for optimized substrate grain metrics with the relative orientation of the magnetic field to the film plane underline the high quality of the films and the advantage of the CSE approach. The obtained LSMO thin films may have an interest for high-resolution low field magnetic sensors application.

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 CaVO 3 and SrVO 3 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.