Papers by Keyword: Thermo-Optical Properties

Abstract: Linked to Surface Plasmon Resonance (SPR) phenomena, optical and thermo-optical properties of metal-dielectric nanocomposite materials including noble metal nanoparticles dispersed in a dielectric host medium are worthily interested. Indeed these materials have been proposed for many applications such as photonics devices, bio sensors and even photo-thermal therapy. Colloidal silver nanoparticles were synthesized by reduction of silver nitrate using of ascorbic acid and citrate as stabilizer agent in a 30°C water bath. The transmission electron microscopy (TEM) micrograph image shows formation of spheroidal silver nanoparticles with an average of large and small diameters about 43 and 34 nm respectively. Extinction spectrum, measured using UV-Vis spectroscopy, represented two peaks located around 420 and 620 nm of wavelength. These peaks are attributed to SPR phenomena and confirm spheroidal and spherical silver nanoparticle formation in solution. Thermo-optical properties of synthesized silver nanocolloids are then evaluated by measuring of extinction spectrum at different temperatures. Results showed an enhancement in thermo-optical properties of silver nanocolloids around the SPR wavelengths. Theoretical analysis, done using Mie and Mie-Gans theories, showed that the different peaks observed in extinction spectrum are related directly to shape effect.

Abstract: The reversible charge ordering transition of (Sm1-x,Cax)MnO3 is associated with strong changes in electrical, magnetic and infrared properties. In this work, normal spectral emissivity is calculated from infrared reflectance of bulk polished ceramics, measured by Fourier Transform Infrared Spectroscopy (FTIR). Emissivity versus temperature shows a sharp transition at the charge ordering transition. By comparing the apparent temperature of the sample with the absolute temperature, we show that (Sm1-x,Cax)MnO3 is a good candidate for infrared furtivity around room temperature.

Abstract: Nd0.3Sm0.7NiO3 ceramic has been synthesised using a sol-gel method and annealing at oxygen pressure. Nd0.3Sm0.7NiO3 exhibits a reversible metal insulator phase transition which is, in the infrared range, responsible of a thermal-optical contrast. Samples are structurally characterized by X-ray diffraction and thermogravimetric analysis. The Nd0.3Sm0.7NiO3 thermal – optical contrast is characterized in the mid-infrared range, using reflectance and thermal-optical measurements.