Adrian‐Marie Philippe

Luxembourg Institute of Science and Technology

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Luca Cipelletti

Université de Montpellier

Laurent J. Michot

PHENIX laboratory

Isabelle Bihannic

Université de Lorraine

Christophe Baravian

Laboratoire Énergies et Mécanique Théorique et Appliquée

E. Barborini

Luxembourg Institute of Science and Technology

Erwan Paineau

Laboratoire de physique des Solides

Patrick Davidson

Laboratoire de physique des Solides

Florian Meneau

Brazilian Synchrotron Light Laboratory

J.E. Martinez Medina

University of Luxembourg

Domenico Larobina

Institute of Polymers, Composites and Biomaterials

Cooperative Institutions

Centre National de la Recherche Scientifique

Luxembourg Institute of Science and Technology

Laboratoire Charles Coulomb

University of Luxembourg

Université de Montpellier

Université de Lorraine

Université Paris-Sud

Forschungszentrum Jülich

Laboratoire Énergies et Mécanique Théorique et Appliquée

Université Paris-Saclay

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The interplay between vanadium and strontium doping in the photoelectrochemical performance of combinatorially deposited single- and dual-doped sodium tantalate thin films

Sustainable materials and technologies (2024)

Corrado Garlisi Vincent Rogé K. Menguelti Petru Lunca‐Popa Marc Michel

The rational design of photoanode materials for photoelectrochemical (PEC) water splitting is a critical aspect towards making this technology available for large-scale renewable energy transition. In this respect, we present here the combinatorial tailoring of the PEC performance of sodium tantalate (NaTaO3)-based ternary and quaternary oxide thin films grown by chemical beam vapor deposition. The incorporation of the selected dopants, namely vanadium and strontium, mainly at the B-site of the orthorhombic perovskite NaTaO3 structure, enhanced the distortion of the TaO6 octahedrons with consequent benefits on the charge delocalization. Mott-Schottky analysis combined with optical characterization, revealed important alterations of the band structure with an increase in the donor density and band gap narrowing, the latter being more significant in V/Sr dual-doped oxides (from 4.5 eV in pristine NaTaO3 to a minimum of 3.6 eV in codoped NaTaO3). Despite an anodic shift of the onset potential for water oxidation, the V-doping and especially V/Sr codoping were found to be the most effective in improving the PEC activity under HgXe light irradiation, with the best performance observed with Sr and V at optimal doping concentrations of 2 and 3 at.%, respectively. Electrochemical impedance spectroscopy and transient open circuit potential measurements shed the light on the synergistic effects of V and Sr doping in boosting charge separation. Our results demonstrate that V/Sr codoping is a viable route to enhance PEC performance of NaTaO3, mainly due to an increased light-harvesting efficiency, suppression of trap states, and efficient charge transfer to the photoanode/electrolyte interface.

Tantalate

10.1016/j.susmat.2024.e01006

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Mucus as an Arrested Phase Separation Gel

Macromolecules (2017)

Adrian‐Marie Philippe Luca Cipelletti Domenico Larobina

We investigate the spontaneous restructuring and aging behavior of pig gastric mucus gels by combining rheology and nonconventional static and dynamic light scattering. We find that the mucus elasticity weakens over time, concomitantly to structural evolution toward a locally more compact configuration and the onset of large scale density fluctuations. We interpret this behavior as stemming from an arrested phase separation, as observed in many gel-forming polymer systems. This scenario is confirmed by space- and time-resolved dynamic light scattering data, showing that the gel restructuring is due to intermittent bursts of spatially correlated rearrangements, leading to ballistic dynamics.

Elasticity

10.1021/acs.macromol.7b00842

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Liquid–crystalline properties of aqueous suspensions of natural clay nanosheets

Liquid Crystals Reviews (2013)

Erwan Paineau Adrian‐Marie Philippe K. Antonova Isabelle Bihannic Patrick Davidson

Clay minerals, like beidellite or nontronite, spontaneously exfoliate in water and form colloidal suspensions of nanosheets. In a given range of concentration, these suspensions display a nematic liquid–crystalline phase whose structure and properties can be conveniently studied in detail by polarized-light microscopy and small-angle X-ray scattering (SAXS). Moreover, in situ SAXS investigations of sheared clay suspensions provide information about their flow properties, both in the isotropic and nematic phases. The colloidal nematic phase shows the classical properties of usual nematics, such as surface anchoring and electric-field and magnetic-field alignment. Thus, nematic single domains can be produced. The isotropic phase also displays strong electro-optic effects in moderate electric fields. Finally, we describe a few examples of applications of such systems and we show how these studies could be extended to suspensions of other types of nanosheets.

Small-angle X-ray scattering

10.1080/21680396.2013.842130

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In-situ SAXS Study of Aqueous Clay Suspensions Submitted to Alternating Current Electric Fields B

The Journal of Physical Chemistry (2012)

Erwan Paineau I. Dozov Adrian‐Marie Philippe Isabelle Bihannic Florian Meneau

Aqueous colloidal suspensions of clay platelets display a sol/gel transition that is not yet understood. Depending on the nature of the clay, liquid-crystalline behavior may also be observed. For example, the suspensions of beidellite display a nematic phase whereas those of montmorillonite do not. Both beidellite and montmorillonite have a “TOT” structure but the structural electric charge is located in the tetrahedral layer for the former and in the octahedral layer for the latter. We built a setup to perform SAXS experiments on complex fluids submitted to an electric field in situ. We found that the fluid nematic phase of beidellite suspensions readily aligns in the field. However, the field had no influence on the gels, showing that the orientational degrees of freedom of the platelets are effectively frozen. Moreover, strong platelet alignment was induced by the field in the isotropic phase of both clays, in a similar way, regardless of their ability to form a nematic phase. This surprising result would suggest that the orientational degrees of freedom are not directly involved in the sol/gel transition. The ability to induce orientational order in the isotropic phase of clay suspensions can be exploited to prepare materials of controlled anisotropy.

Small-angle X-ray scattering

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Experimental Insights on the Stability of Core-Shell Structure in Single Sn/Snox Spherical Nanoparticles During Room Temperature Oxidation

Marc Heggen J.E. Martinez Medina Adrian‐Marie Philippe E. Barborini

10.2139/ssrn.4990094

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An ABC method for posterior sampling of marked point processes

arXiv (Cornell University) (2015)

Radu S. Stoica Adrian‐Marie Philippe Pablo Gregori Jorge Mateu

This paper presents an ABC algorithm, called ABC Shadow, that can be applied to sample marked point processes posterior densities. The proposed method uses the ideas given by the auxiliary variable Metropolis-Hastings of (M{\o}ller et al., 2006). The obtained algorithm solves the main condition to be fulfilled by any ABC algorithm, in order to be useful in practice. This condition requires enough samples in the parameter space region, induced by the observed statistics (Blum, 2010). The algorithm is tested on entirely known exponential family models and on two point processes, the Strauss and the Candy models.

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Study of heterogeneous dynamics by Holographic Time Resolved Correlation (HTRC)

Adrian‐Marie Philippe Luca Cipelletti Anne-Caroline Genix M. Groß

HTRC is a new ligth scattering technique that measures by holography the field amplitude scattered by a sample, and analyze its spatial correlations. HTRC outperforms other light scattering techniques like DLS, DWS and TRC.

Dynamics

Sample (material)

10.1364/3d.2018.jw4a.27

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Effects of Added Silica Nanoparticles on the Nematic Liquid Crystal Phase Formation in Beidellite Suspensions

The Journal of Physical Chemistry B (2014)

Jasper Landman Erwan Paineau Patrick Davidson Isabelle Bihannic Laurent J. Michot

In this article, we present a study of the liquid crystal phase behavior of mixed suspensions of the natural smectite clay mineral beidellite and nonadsorbing colloidal silica particles. While virtually all smectite clays dispersed in water form gels at very low concentrations, beidellite displays a first order isotropic–nematic phase transition before gel formation (J. Phys. Chem. B, 2009, 113, 15858−15869). The addition of silica nanospheres shifts the concentrations of the coexisting isotropic and nematic phases to slightly higher values while at the same time markedly accelerating the phase separation process. Furthermore, beidellite suspensions at volume fractions above the isotropic–nematic phase separation, trapped in a kinetically arrested gel state, liquefy on the addition of silica nanospheres and proceed to isotropic–nematic phase separation. Using small-angle X-ray scattering (SAXS), we probe the structural changes caused by the addition of the silica nanospheres, and we relate the modification of the phase transition kinetics to the change of the rheological properties.

Small-angle X-ray scattering

10.1021/jp500036v

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Citations (42)

Shifting the Paradigm: A Functional Hole‐Selective Transport Layer for Chalcopyrite Solar Cells

Solar RRL (2024)

Taowen Wang Longfei Song Sevan Gharabeiki Mohit Sood Aubin JC. M. Prot

High‐efficiency Cu(In,Ga)Se 2 solar cells rely on Ga grading to mitigate back surface recombination. However, the inhomogeneous absorber has drawbacks, including increased non‐radiative loss and inadequate absorption. Therefore, literatures demand a paradigm shift of using a hole‐transport layer to passivate the back surface. Herein, a functional hole‐transport layer is demonstrated as an alternative to Ga grading. The novel hole‐transport layer is prepared as a double‐layer: co‐evaporated CuGaSe 2 covered by solution combustion synthesis prepared In 2 O 3 . As demonstrated by micrographs, elemental mapping, and photoluminescence spectroscopy, the oxide layer improves thermal stability and prevents Ga diffusion. However, during the absorber deposition, a complete ion exchange of In and Ga converts CuGaSe 2 /In 2 O 3 into CuInSe 2 /GaO x . Incorporating this hole‐transport layer in co‐evaporated nongraded CuInSe 2 solar cells leads to significantly increased minority carrier lifetime from 5 to 113 ns, yielding an 80 meV improvement in quasi‐Fermi‐level splitting. The devices exhibit improved open‐circuit voltage, as well as a promising fill factor of over 71%, indicating good hole‐transport properties. In these results, the passivation effect and good hole‐transport properties of the hole‐transport layer are experimentally demonstrated. Thus, high‐efficiency solar cells can be achieved by using a functional hole‐transport layer without relying on Ga grading.

Passivation

10.1002/solr.202400212

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Reflection and transmission of radio waves at a dielectric slab with variable permittivity

IRE Transactions on Antennas and Propagation (1973)

Adrian‐Marie Philippe

Expressions for the reflection and the transmission power coefficients are derived for the case where a plane wave is obliquely incident on a dielectric slab in which the relative permittivity decreases symmetrically according to a 1/z^{2} law from a given maximum value at the plane of symmetry and tends towards unity at the two faces of the slab. The effect of the curvature and other parameters governing the inverse square profile on the transparency property of the material at radar frequencies has been studied within a large d/\lambda range where d is the half-slab thickness and \lambda the wavelength of the incident wave.

Slab

Reflection

10.1109/tap.1973.1140447

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Citations (17)