A5005708634- Glass properties and applications
- Thermal Radiation and Cooling Technologies
- Radiative Heat Transfer Studies
- Calibration and Measurement Techniques
- Magnetic and transport properties of perovskites and related materials
- Solid-state spectroscopy and crystallography
- Quantum Electrodynamics and Casimir Effect
- Luminescence Properties of Advanced Materials
- Multiferroics and related materials
- Silicon Nanostructures and Photoluminescence
- Material Dynamics and Properties
- Advanced Condensed Matter Physics
- Thermography and Photoacoustic Techniques
- Pigment Synthesis and Properties
- Mineralogy and Gemology Studies
- Advanced Thermodynamics and Statistical Mechanics
- High-pressure geophysics and materials
- Thermal properties of materials
- Mechanical and Optical Resonators
- Photonic Crystals and Applications
- X-ray Diffraction in Crystallography
- Advanced ceramic materials synthesis
- Semiconductor materials and devices
- High-Temperature Coating Behaviors
- Material Science and Thermodynamics
Centre National de la Recherche Scientifique
2015-2024
Conditions Extrêmes et Matériaux Haute Température et Irradiation
2015-2024
Université d'Orléans
2014-2023
University of Puerto Rico System
2013
Surface electromagnetic waves double thermal conductivity of thin SiN membranes.
By means of fluctuational electrodynamics, we calculate radiative heat flux between two planar materials respectively made SiC and SiO 2 .More specifically, focus on a first (direct) situation where one the (for example SiC) is at ambient temperature whereas second material higher one, then study (reverse) temperatures are inverted.When fluxes corresponding to situations different, said exhibit thermal rectification, property with potential applications in regulation.Rectification variations...
This paper aims to study the mechanical behavior and surface chemistry in relationship with moisture content of Iroko (Milicia excelsa), Bilinga (Nauclea diderrichii), Tali (Erythrophleum suaveolens). Mechanical characterization was done experimentally using tensile bending tests. Chemical semi quantitative analysis wood at 10%, 15%, 20% 30% investigated attenuated total reflectance Fourier transform infrared spectroscopy. The main chemical functions involved by presence water were...
A spectroscopic method to measure directional spectral emissivity for homogeneous and heterogeneous semi-transparent materials, giving access a large 10–12 000 cm−1 range temperatures lying between 600 3000 K is reported. Sample heating supplied by carbon dioxide laser the blackbody flux reference obtained with lanthanum chromite furnace. Experimental results this setup on several dielectric oxides such as silica, alumina, magnesia are in good agreement an indirect based Kirchhoff’s laws....
The highly visible and infrared (up to 6 μm) transparent Sr3Al2O6 polycrystalline ceramic was obtained by full crystallization of the corresponding glass composition. synthesis direct congruent processes are described, material transparency is discussed in light its microstructure. This new exhibits a high density (i.e., complete absence porosity) micrometer-scale crystallites with very thin grain boundaries. These microstructural characteristics, inherent preparation method, minimize...
Structural and optical properties of stable glasses in the Y2O3–CaO–B2O3 system, containing same Y/Ca ratio as YCa4O(BO3)3 (YCOB) crystal, were determined from Raman reflectance infrared spectroscopy. Changes functions with composition are associated an increase number non-bridging oxygen to calcium/yttrium oxides content. Refractive indexes values (from 1.597 1.627 at λ=2 μm) good agreement those YCOB indication that these potential candidates for applications due their ease shaping large...
An yttria-alumina glass incorporating 4 wt % of SiO2 was prepared by the use an aerodynamic levitator equipped with a laser heating device. Upon post synthesis annealing, is observed to exhibit crystallization below transition temperature. In current study, this unusual behavior examined using powder X-ray diffraction and infrared spectroscopy follow crystallinity optical absorbance as function annealing treatment. Double-resonance 27Al/29Si NMR synchrotron experiments demonstrate that Si...
The viscosity and electrical conductivity the ${}^{27}\mathrm{Al}$ spin-lattice relaxation time have been measured for two calcium aluminosilicate liquids or glasses. At high temperature, times three processes are same to within experimental errors. This similarity points a coupling between rate of Al-O bond exchange structural involved in viscous flow, which also controls motion Ca ions that is associated with conductivity. Near glass transition, decoupling indicated by fact characteristic...
A new approach to modeling using semi-quantum dielectric function models is proposed for the retrieval of optical functions from infrared spectra. The powerful points method are shown throughout analysis two semitransparent materials, MgO and KBr. All results discussed in light those obtained with classical techniques. This type model able retrieve, example, extinction index a range that covers at least six orders magnitude gives access highly valuable information about high-order phonon processes.
The normal spectral emittance of a partially yttria-stabilized hafnia (YSH) ceramic has been measured by infrared spectroscopy in range going from 60 to 17 500 cm−1 (0.075–2.2 eV), and up 2350 K. Using these experimental data, the temperature dependence absorption coefficient total have calculated. physical mechanisms explaining features whole set spectra are exposed qualitatively. weight each contribution is then discussed for interpreting influence on temperatures (1200–2500 K) where YSH...
A photonic thermal diode capitalizing on the strong contrast of Nb permittivity around its critical temperature separating normal and superconducting states is proposed analyzed in both near- far-fields. For a with terminals made SiO2 operating at temperatures 1 K 8.7 K, rectification factor maximized to 71%, which occurs for terminal separation distance 59.9 μm among highest values reported literature. other temperatures, takes smaller values, but can still be optimized different transition...
Far- and mid-infrared spectroscopy is presented as a powerful nondestructive tool for estimation of the porosity oxide ceramic films, which are typically employed part thermal barrier coatings. A radiative model that takes into account includes optical response thin films has been used. Provided pore size small enough compared to infrared wavelength, level can be included an adjustable parameter effective medium theories (EMT) such Maxwell-Garnet or Bruggeman. Periodic interferential...
Abstract Graphene has emerged as a promising material for infrared (IR) photodetectors and plasmonics. In this context, wafer scale epitaxial graphene on SiC is of great interest in variety applications optics nanoelectronics. Here we present IR reflectance spectroscopy grown epitaxially the C-face 6H-SiC over broad optical range, from terahertz (THz) to mid-infrared (MIR). Contrary transmittance, measurements are not hampered by transmission window substrate particular Reststrahlen band...
The temperature behaviour in the range 22-500 °C of dielectric permittivity infrared is investigated for CaF(2), BaF(2) and Al(2)O(3) through reflectivity measurements. retrieved by fitting spectra with a model taking into account multiphonon contributions. results extrapolated from measurements are applied to predict temperature-dependent atom-surface van der Waals interaction. We specifically consider as atom interest Cs(8P(3/2)), most relevant virtual couplings which fall thermal...