Browsing by Author "GHAYAH MOHAMMED SALEM ALSALEEM"

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Plasmonic Nanomaterials with Protein Nanotubes Studied using Fluorescence and Raman
(Saudi Digital Library) GHAYAH MOHAMMED SALEM ALSALEEM; RICE
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The synthesis and characterization of long- lasting phosphorescent compounds of SrAl2O4:Eu2+, Dy3+ class for possible use in solar energy harvest and conversion
GHAYAH MOHAMMED SALEM ALSALEEM; ravi Thampi
This study focuses on improving the synthesis of selected Long-Lasting Phosphorous (LLP) compounds of SrAl2O4:Eu2+, Dy3+ class. Starting with a review of the state-of-the-art LLP materials having an afterglow of at least an hour or more, the report analyses the methods and materials used for such promising LLP materials and subsequent laboratory work, long-lasting phosphorescence compounds were defined as materials that have an afterglow decay time greater than 1 hour. At the start, the preparation methods used were similar to procedures reported in the literature. Temperature, dopant levels and mixing methods were later varied to understand the individual effects of the various parameters on the long-lasting phosphorescence characteristics of the LLP materials. To spare valuable and rare materials, the study adopted and used a novel approach by first preparing the required compounds on a trial basis in a differential scanning calorimeter (DSC) sample holder taking amounts in the order of milligrams. This method using DSC turns out to be a very useful technique for preparing samples in minute amounts and at the same time gather calorimetric data as well. Since only small amounts are sufficient to study phosphorescence lifetime in a preliminary manner, the technique suits this type of research. and resulted in the finding that 1200°C was the only temperature that the compound could be heated to in the DSC to achieve any phosphorescence. However, the temperatures above 1300°C were investigated further using high temperature furnace methods as well. The variation of mixing method and co-dopant level in the strontium aluminate compounds resulted in the finding that the dry mixing method using a Turbula mixer resulted in the longest afterglow. However, in the batches where the materials were mixed using sonication, the phosphorescent time was found to be reduced, indicating that the nature of intimate mixing is a crucial parameter to be monitored correctly. The use of such materials for solar cell applications has been demonstrated through a simple proof of concept. Studies have shown that it can be upscaled. Thus, it is now a proven method to improve the PV solar cell performance.
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