Thermal properties of 15-mol% gadolinia doped ceria thin films prepared by pulsed laser ablation

Thermal properties of 15-mol% gadolinia doped ceria thin films (Ce_0.85Gd_0.15 O_1.925) prepared by pulsed laser ablation on silicon substrates in the temperature range 473–973 K are presented. Thermal diffusivities and thermal conductivities were evaluated using photoacoustic spectroscopy. The influence of grain size on thermal properties of the films as a function of deposition temperature is studied. It is observed that the thermal diffusivity and the conductivity of these films decreases up to 873 K and then increases with substrate temperatures. The thermal properties obtained in these films are discussed on the basis of influence of grain size on phonon scattering.     

EPR and photoacoustic studies on 30 kev H ion-implanted n-GaAs

Electron paramagnetic resonance (EPR) measurements are carried out on the 30 keV H⁺ion-implanted, Si-doped GaAs(1 0 0) for various doses from 10¹⁴ to 10¹⁷ cm⁻². The results are correlated with photoacoustic and photoluminescence measurements. All the measurements confirm the sign change of charge carrier at a dose of 10¹⁵ cm⁻².     

X-ray attenuation around <Emphasis Type="Italic">K</Emphasis>-edge of Zr,Nb, Mo and Pd: A comparative study using proton-induced X-ray emission and <Superscript>241</Superscript>Am gamma rays

Mass attenuation coefficients (μ/ρ) for Zr, Nb, Mo and Pd elements around their K-edges are measured at 14 energies in the range 15.744–28.564 keV using secondary excitation from thin Zr, Nb, Mo, Rh, Pd, Cd and Sn foils. The measurements were carried out at the K _α and K _β energy values of the target elements by two techniques: (1) Proton-induced X-ray emission (PIXE) and (2) ²⁴¹Am (300 mCi) source. In PIXE, 2 MeV proton-excited X-rays were detected by a Si(Li) detector. In the second case, X-rays excited by 59.54 keV photons from the targets were counted by an HPGe detector under a narrow beam good geometry set-up with sufficient shielding. The results are consistent with theoretical values derived from the XCOM package and indicate that the PIXE data have better statistical accuracy.     

Spectroscopic investigations of 1.06 μm emission in Nd-doped alkali niobium zinc tellurite glasses

Thermal, structural and optical properties of Nd³⁺ ions in tellurite glass (TeO₂-ZnO-Na₂O-Li₂O-Nb₂O₅) have been investigated. Differential thermal analysis revealed reasonably good forming tendency of the glass composition. FTIR spectra were used to analyze the functional groups present in the glass. Judd-Ofelt intensity parameters were derived from the absorption spectrum and used to calculate the radiative lifetime, branching ratio and stimulated emission cross-section of the ⁴F_3/2→⁴I_9/2, _{11/2, 13/2} transitions. The quantum efficiency of the ⁴F_3/2 level is comparable as well as higher than the typical value of the other tellurite based glasses. The decay from the ⁴F_3/2 level is found to be single exponential for different concentrations of Nd³⁺ ions with a shortening of lifetime with increasing concentration. The experimental values of branching ratio and saturation intensity of ⁴F_3/2→⁴I_11/2 transition indicate the favourable lasing action with low threshold power.     

Flow visualization of supersonic transverse jet over Mach 2 freestream of a sharp cone

Graphical abstract