Defect and Diffusion Forum Vol. 344

Abstract: The spin Hamiltonian parameters (g factors g||, g and the hyperfine structure constants A||, A) for the Cu²⁺ centers in alkali barium borate glasses were theoretically studied based on the high-order perturbation formulas of these parameters for a 3d⁹ ion in a tetragonally elongated octahedron. From the calculations, the ligand octahedra around Cu²⁺ are suggested to suffer about 9.4%, 10.7%, and 11.1% relative elongation along C4 axis for the alkali barium borate glasses (Li-Ba-B, Na-Ba-B and K-Ba-B, respectively), the results are in good agreement with the observed values. In addition, the negative signs for A|| and A of the studied Cu²⁺ centers were also suggested in the discussion.

Abstract: The track etch detector, CR-39, in common use is the most sensitive to recording charged particles. The CR-39 polymer samples were irradiated with alpha particle at different energies (2.17 MeV and 3.95 MeV) and fixed fluence followed by chemical etching with different times (1.50, 3.00 and 6.00 hrs). The formed tracks in CR-39 due to irradiations were visualized by using etching technique. The optical properties of CR-39 polymer after etching processes were studied with ultraviolet-visible (UV-vis) spectroscopy. Moreover, the optical band gap energy was calculated for the different etching times (1.50, 3.00 and 6.00 hrs). The average value of the track diameter of irradiation at 2.17 MeV and etching time 1.5 hr is fairly large compared with its value at 3.95 MeV. This is due to the production of defect levels in the band gap of polymer at the 2.17 MeV. The virgin and 2.17 MeV samples at 3.00 and 6.00 hrs have the same optical behavior resulted in the etching solution at those etching times has reached the end of the alpha particle path and progress in all the directions in the bulk of CR-39 with the same rate.

Abstract: In this paper different techniques for sandwich thin film production, characterization and interfacial reactions have been reviewed in order to understand the kinetic behaviour in the above systems. The contact and composite resistance measurements are the indirect methods for this purpose, while X-ray diffraction studies (XRD), Transmission electron microscopy (TEM), Scanning electron microscopy (SEM), Rutherford backscattering (RBS), Auger electron spectroscopy (AES), secondary ion mass spectrometry (SIMS), ion sputtering spectrometry (ISS), X-ray photoelectron spectroscopy (XPS) which is also referred to as electron spectroscopy for chemical analysis (ESCA) and atomic force microscopy (AFM) are some of the direct methods. Trends indicate that interfacial reactions start at room temperature.

Abstract: The aim of this work is to establish a correlation coefficient between the positron annihilation lifetime technique (PALS) and the Vickers hardness for the heat treatable aluminum alloys (6066, 6063).The potential of positron annihilation spectroscopy in the study of light alloys is illustrated with special regards to age hardening, severe plastic deformation, annealing and quenching in aluminum alloys. Vickers hardness is the standard method for measuring the hardness of metals, particularly those with extremely hard surfaces. Accordingly, a correlation coefficient of 90 % between τ and Hv is obtained. This correlation can help us to explain many behaviors of these alloys under deferent conditions.