and Perspectives Sophie Carenco,†,‡,§,∥,⊥ David Portehault,*,†,‡,§ Ced́ric Boissier̀e,†,‡,§ Nicolas Meźailles, and Cleḿent Sanchez*,†,‡,§ †Chimie de la Matier̀e Condenseé de Paris, UPMC Univ Paris 06, UMR 7574, Colleg̀e de France, 11 Place Marcelin Berthelot, 75231 Paris Cedex 05, France ‡Chimie de la Matier̀e Condenseé de Paris, CNRS, UMR 77574, Colleg̀e de France, 11 Place Marcellin Berthelot, 75231 Paris Cedex 05, France Chimie de la Matier̀e Condenseé de Paris, Colleg̀e de France, 11 Place Marcellin Berthelot, 75231 Paris Cedex 05, France Laboratory Heteroelements and Coordination, Chemistry Department, Ecole Polytechnique, CNRS-UMR 7653, Palaiseau, France

Nanoscaled metal borides and phosphides: recent developments and perspectives

Compact solid-state sources of terahertz (THz) radiation are being sought for sensing, imaging, and spectroscopy applications across the physical and biological sciences. We demonstrate that coherent continuous-wave THz radiation of sizable power can be extracted from intrinsic Josephson junctions in the layered high-temperature superconductor Bi2Sr2CaCu2O8. In analogy to a laser cavity, the excitation of an electromagnetic cavity resonance inside the sample generates a macroscopic coherent state in which a large number of junctions are synchronized to oscillate in phase. The emission power is found to increase as the square of the number of junctions reaching values of 0.5 microwatt at frequencies up to 0.85 THz, and persists up to ∼50 kelvin. These results should stimulate the development of superconducting compact sources of THz radiation.

http://absimage.aps.org/image/MAR08/MWS_MAR08-2007-004672.pdf

Emission of Coherent THz-Radiation from Superconductors.

Comparison of the high temperature thermoelectric properties for Ag-doped and Ag-added Ca3Co4O9

Recent advances in oxide thermoelectric materials and modules

In the present work, six bismuth borate glass samples with chemical formula (75−x)B2O3–xBi2O3–10CaO–10Na2O–5Al2O3, (x = 0.0–25.0 mol%) have been manufactured. UV–visible spectral distributions for the investigated system were measured in the range of 250–850 nm. The optical absorption data showed the existence of allowed indirect transitions. The optical energy gap values (
 $$E_{{\text{g}}}^{{{\text{opt}}.}}$$
 ) via Tauc’s model vary from 3.39 to 2.45 eV. The complex dielectric constant (
 $$\hat {\varepsilon }$$
 ) was evaluated. All the optical parameters are found to be sensitive to the concentration of Bi2O3. Also, gamma photons’ attenuation features such as the mass attenuation coefficient (µ/ρ), gamma photon transmission function (I/Io), effective atomic number (Zeff), and half value thickness (HVT) for the investigated glass samples were estimated using MCNPX code and XCOM program in the range of 0.356–1.33 MeV. Replacement of B2O3 by Bi2O3 enhances the ability of glass samples to attenuate gamma photons. The results revealed that the studied glasses can be considered as candidate for optical fiber, devices, and gamma shieling.

Optical properties and gamma-shielding features of bismuth borate glasses

Synthesis and characterization of Er-substituted Bi-2223 H-Tc glass–ceramic superconductors

An analysis of load-depth data in depth-sensing microindentation experiments for intermetallic MgB2

The effect of Sn content on mechanical, magnetization and shape memory behavior in NiMnSn alloys

In this study, the Ca3−xSbxCo4O9 (x = 0.0, 0.5, 0.75 and 1.0) system was fabricated using solid-state reaction technique. From the XRD analysis, it was found that increase of the Sb concentration in the system caused formation of impurity phases and therefore a distortion in the main lattice. The SEM-EDX results showed that the grain size reduced with increasing Sb in the Ca3Co4O9 system. The resistivity, ρ, value increased with increasing the Sb-content and insulating behavior was obtained as the temperature was decreased. The samples fabricated have positive thermoelectric power, S, value, suggesting that holes are dominant charge carriers in the samples. S value decreased with decreasing the temperature. The Fermi energy, E
 F
 , and the carrier concentration, n, decreased by the Sb-substitution. The Sb-substitution caused a decrease of thermal conductivity, κ which is due to reduction of the phonon thermal conductivity, κ
 ph, in the system. Figure of merit, ZT, value decreased significantly due to strongly increase in ρ. The impurities, defects and distortion with substitution of Sb are responsible for large variation on electrical and thermal transport properties.

Low temperature electrical and thermal transport properties of the Ca3−xSbxCo4O9 system

We have melt quenched a series of Ga substituted Bi2-xGaxSr2Ca2Cu3O10+y samples with the compositions with x = 02, 04, 06, 08 and 10 Microstructure, thermal properties including crystallization activation energy, magnetic and superconducting properties were investigated We have found that Ga3+ ions have a solid solubility limit in the BSCCO system and this limit was passed at x = 06 Below this limit HTc BSCCO n = 3 phase was obtained, but after the solid solubility limit samples yield multiphase superconducting properties Extended heat treatment at 840?C displayed no suppression of the solid solubility limit The crystallization kinetic studies were investigated using non-isothermal kinetic models of Kissinger and Augis-Bennet Higher crystallization activation energies, Ea, were obtained compared to unsubstituted BSCCO materials, glassification improved and glass handling time increased The substitution had a slight effect on Jc, the flux pinning in the material was improved and better Jc values were obtained below the solid solubility limit

http://iopscience.iop.org/article/10.1088/0953-2048/13/7/308/pdf

M.A. Aksan

Papers

Synthesis and characterization of Er-substituted Bi-2223 H-Tc glass–ceramic superconductors

An analysis of load-depth data in depth-sensing microindentation experiments for intermetallic MgB2

The effect of Sn content on mechanical, magnetization and shape memory behavior in NiMnSn alloys

Low temperature electrical and thermal transport properties of the Ca3−xSbxCo4O9 system

Synthesis and characterization of glass-ceramic Bi2-xGaxSr2Ca2Cu3O10+y superconductors