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Jean-François Pierson

Bio: Jean-François Pierson is an academic researcher from University of Lorraine. The author has contributed to research in topics: Thin film & Sputtering. The author has an hindex of 31, co-authored 181 publications receiving 3670 citations. Previous affiliations of Jean-François Pierson include University of Franche-Comté & Mines ParisTech.


Papers
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Journal ArticleDOI
TL;DR: In this article, a combined experimental and theoretical study on the vibrational properties of tenorite CuO and paramelaconite Cu4O3 was performed using Raman scattering and infrared absorption spectroscopy.
Abstract: A combined experimental and theoretical study is reported on the vibrational properties of tenorite CuO and paramelaconite Cu4O3. The optically active modes have been measured by Raman scattering and infrared absorption spectroscopy. First-principles calculations have been carried out with the LDA+U approach to account for strong electron correlation in the copper oxides. The vibrational properties have been computed ab initio using the so-called direct method. Excellent agreement is found between the measured Raman and infrared peak positions and the calculated phonon frequencies at the Brillouin zone center, which allows the assignment of all prominent peaks of the Cu4O3 spectra. Through a detailed analysis of the displacement eigenvectors, it is shown that a close relationship exists between the Raman modes of CuO and Cu4O3.

409 citations

Journal ArticleDOI
TL;DR: In this article, the thermal stability in air of cuprite, paramelaconite and tenorite films has been investigated and the results show that the stability of Cu2O and Cu4O3 films in air is influenced by the thickness and/or the texture of the films.

232 citations

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TL;DR: In this paper, a joint experimental and theoretical study for the electronic structures of copper oxides including CuO, and the metastable mixed-valence oxide (MVO) was presented.
Abstract: A joint experimental and theoretical study is presented for the electronic structures of copper oxides including $\mathrm{C}{\mathrm{u}}_{2}\mathrm{O}$, CuO, and the metastable mixed-valence oxide $\mathrm{C}{\mathrm{u}}_{4}{\mathrm{O}}_{3}$. The optical band gap is determined by experimental optical absorption coefficient, and the electronic structure in valence and conduction bands is probed by photoemission and electron energy loss spectroscopies, respectively. The experimental results are compared with many-body $GW$ calculations utilizing an additional on-site potential for $d$-orbital energies that facilitates tractable and predictive computations. The side-by-side comparison between the three oxides, including a band insulator $(\mathrm{C}{\mathrm{u}}_{2}\mathrm{O})$ and two Mott/charge-transfer insulators (CuO, $\mathrm{C}{\mathrm{u}}_{4}{\mathrm{O}}_{3})$ leads to a consistent picture for the optical and band-structure properties of the Cu oxides, strongly supporting indirect band gaps of about 1.2 and 0.8 eV in CuO and $\mathrm{C}{\mathrm{u}}_{4}{\mathrm{O}}_{3}$, respectively. This comparison also points towards surface oxidation and reduction effects that can complicate the interpretation of the photoemission spectra.

182 citations

Journal ArticleDOI
TL;DR: In this paper, copper, silver, and gold targets were sputtered in various reactive gas mixtures (Ar-N 2, Ar-O 2, and Ar-CH 4 ) to compare the reactivity of noble metal atoms during the sputtering process.

174 citations

Journal ArticleDOI
01 Jun 2002-Vacuum
TL;DR: In this paper, the lattice constants of the Cu3N lattice constant have been determined and the optical band gap of the films have been compared with the nitrogen flow rate, and the nonstoichiometry, the mean crystal size, the direction of preferred orientation and the surface morphology of the film have been correlated.

121 citations


Cited by
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TL;DR: Transparent conductors (TCs) have a multitude of applications for solar energy utilization and for energy savings, especially in buildings as discussed by the authors, which leads naturally to considerations of spectral selectivity, angular selectivity, and temporal variability of TCs, as covered in three subsequent sections.

1,471 citations

Journal ArticleDOI
TL;DR: The state-of-the-art progress toward mechanisms, new materials, and novel device designs for supercapacitors is summarized and key technical challenges are highlighted regarding further research in this thriving field.
Abstract: Notably, many significant breakthroughs for a new generation of supercapacitors have been reported in recent years, related to theoretical understanding, material synthesis and device designs. Herein, we summarize the state-of-the-art progress toward mechanisms, new materials, and novel device designs for supercapacitors. Firstly, fundamental understanding of the mechanism is mainly focused on the relationship between the structural properties of electrode materials and their electrochemical performances based on some in situ characterization techniques and simulations. Secondly, some emerging electrode materials are discussed, including metal–organic frameworks (MOFs), covalent organic frameworks (COFs), MXenes, metal nitrides, black phosphorus, LaMnO3, and RbAg4I5/graphite. Thirdly, the device innovations for the next generation of supercapacitors are provided successively, mainly emphasizing flow supercapacitors, alternating current (AC) line-filtering supercapacitors, redox electrolyte enhanced supercapacitors, metal ion hybrid supercapacitors, micro-supercapacitors (fiber, plane and three-dimensional) and multifunctional supercapacitors including electrochromic supercapacitors, self-healing supercapacitors, piezoelectric supercapacitors, shape-memory supercapacitors, thermal self-protective supercapacitors, thermal self-charging supercapacitors, and photo self-charging supercapacitors. Finally, the future developments and key technical challenges are highlighted regarding further research in this thriving field.

1,397 citations

Journal ArticleDOI
TL;DR: In this paper, a conceptual model for structural characteristics of amorphous W oxide films, based on notions of defects in the ideal ammorphous state, is given for thin film deposition by sputtering, electronic band structure and ion diffusion.
Abstract: Electrochromic (EC) materials are able to change their optical properties, reversibly and persistently, by the application of an electrical voltage. These materials can be integrated in multilayer devices capable of modulating the optical transmittance between widely separated extrema. We first review the recent literature on inorganic EC materials and point out that today's research is focused on tungsten oxide (colouring under charge insertion) and nickel oxide (colouring under charge extraction). The properties of thin films of these materials are then discussed in detail with foci on recent results from two comprehensive investigations in the authors' laboratory. A logical exposition is obtained by covering, in sequence, structural features, thin film deposition (by sputtering), electronic band structure, and ion diffusion. A novel conceptual model is given for structural characteristics of amorphous W oxide films, based on notions of defects in the ideal amorphous state. It is also shown that the conduction band density of states is obtainable from simple electrochemical chronopotentiometry. Ion intercalation causes the charge-compensating electrons to enter localized states, implying that the optical absorption underlying the electrochromism can be described as ensuing from transitions between occupied and empty localized conduction band states. A fully quantitative theory of such transitions is not available, but the optical absorption can be modeled more phenomenologically as due to a superposition of transitions between different charge states of the W ions (6+, 5+, and 4+). The Ni oxide films were found to have a porous structure comprised of small grains. The data are consistent with EC coloration being a surface phenomenon, most likely confined to the outer parts of the grains. Initial electrochemical cycling was found to transform hydrated Ni oxide into hydroxide and oxy-hydroxide phases on the grain surfaces. Electrochromism in thus stabilized films is consistent with reversible changes between Ni hydroxide and oxy-hydroxide, in accordance with the Bode reaction scheme. An extension of this model is put forward to account for changes of NiO to Ni2O3. It was demonstrated that electrochromism is associated solely with proton transfer. Data on chemical diffusion coefficients are interpreted for polycrystalline W oxide and Ni oxide in terms of the lattice gas model with interaction. The later part of this review is of a more technological and applications oriented character and is based on the fact that EC devices with large optical modulation can be accomplished essentially by connecting W-oxide-based and Ni-oxide-based films through a layer serving as a pure ion conductor. Specifically, we treat methods to enhance the bleached-state transmittance by mixing the Ni oxide with other oxides characterized by wide band gaps, and we also discuss pre-assembly charge insertion and extraction by facile gas treatments of the films, as well as practical device manufacturing and device testing. Here the emphasis is on novel flexible polyester-foil-based devices. The final part deals with applications with emphasis on architectural “smart” windows capable of achieving improved indoor comfort jointly with significant energy savings due to lowered demands for space cooling. Eyewear applications are touched upon as well.

1,156 citations

Journal ArticleDOI
TL;DR: In this article, the authors reviewed the recent advances in fabrication of materials and devices and provided a critical analysis of reported performances of micro-supercapacitors, including intrinsic properties of electrode materials and electrolyte, architectural design of the device and fabrication methods.
Abstract: Miniaturized energy storage is essential for the continuous development and further miniaturization of electronic devices. Electrochemical capacitors (ECs), also called supercapacitors, are energy storage devices with a high power density, fast charge and discharge rates, and long service life. Small-scale supercapacitors, or micro-supercapacitors, can be integrated with microelectronic devices to work as stand-alone power sources or as efficient energy storage units complementing batteries and energy harvesters, leading to wider use of these devices in many industries. In recent years, the research in this field has rapidly advanced and micro-supercapacitors with improved storage capacity and power density have been developed. The important factors affecting the performance of micro-supercapacitors are the intrinsic properties of electrode materials and electrolyte, architectural design of the device and the fabrication methods. This paper reviews the recent advances in fabrication of materials and devices and provides a critical analysis of reported performances of micro-supercapacitors.

1,118 citations

Journal ArticleDOI
TL;DR: A comprehensive review of recent synthetic methods along with associated synthesis mechanisms, characterization, fundamental properties, and promising applications of Cupric oxide (CuO) nanostructures is presented in this article.

1,030 citations