Publications by authors named "Bachir Bentria"

2 Publications

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Synthesis and luminescence spectroscopy study of a novel orange-red colour emissions phosphor based on Tb ion-doped Na ZnP O.

Luminescence 2021 Mar 8;36(2):489-496. Epub 2021 Feb 8.

Laser Physics Department/Physics Division, Nuclear Research Center of Algiers-CRNA, 02 Bd. Frantz Fanon, Alger, BP, Algeria.

Here, we report the synthesis and study of new orange-red (OR) colour-emitting phosphors Na ZnP O :xTb (x = 1, 1.25, 1.5, and 1.75 mol%) using a conventional solid-state reaction. The sample crystallographic structures and their room temperature photoluminescence properties were measured using X-ray powder diffraction, excitation and emission spectra, as well as emission decay curves. X-ray diffraction analysis showed an isostructural tetragonal structure for all the doped materials with no impurities. Several colour emissions corresponding to D → F (blue), D → F (green), D → F (orange) and D → F (red) intraconfigurational transitions were observed and investigated. These colours were dominated by the OR colours. D energy level lifetime was independent of Tb concentration. Various radiative and luminescence parameters, such as experimental branching ratio, radiative decay rate, and luminescence quantum efficiencies, were calculated and discussed. Chromaticity diagram calculations illustrated an orange emission for all the studied materials.
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March 2021

Toward a better understanding of the enhancing/embrittling effects of impurities in Nickel grain boundaries.

Sci Rep 2019 Oct 1;9(1):14024. Epub 2019 Oct 1.

College of Science, Physics department, Alfaisal University, P.O. Box 50927, Riyadh, 11533, Saudi Arabia.

The fracture path follows grain boundaries (GB) in most metallic system under tensile test. In general, impurities, even in ppm concentration, that segregate to these boundaries can remarkably change materials mechanical properties. Predicting impurities segregation effects in Nickel super-alloys might not be seen as intuitive and perhaps more fundamental understanding is needed. We performed a density functional theory calculation to elucidate the effect of eight light elements (B, C, N, O, Al, Si, P and S) and twelve transition metal elements (Tc, Ti, V, Cr, Mn, Zr, Nb, Mo, Hf, Ta, W, Re) on Nickel ∑5(210) grain boundary formation and its Ni free surface. The effect of impurities was carefully examined by calculating different properties such as segregation, binding and cohesive energies, strengthening/embrittling potency and the theoretical tensile strength. Additionally, we employed the electron density differences and magnetic effects to explain why and how impurities such as B, S, V, Nb, Mn and W affect Nickel ∑5 GB. We used the generated data calculated on equal footing, to develop a fundamental understanding on impurity effect. A clear and strong correlation is found between difference in magnetic moment change between isolated and imbedded impurity atom on one hand and the tensile strength on the other hand. The higher the loss of the magnetic moment, the more the impurity consolidates the GB.
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October 2019