Effect of Annealing Temperature on Growth Particles of YAG: Ce +3 Phosphor and White Light Chromaticity Values

In the present work white-emitting Y3A15O12:xCe3 (x = 0.04) nanophosphor in the form Of powder were synthesized by a microwave-induced combustion synthesis method (MW) Using metal nitrates as precursors and urea as fuel. By covering blue light-emitting diodes (blue-LED, 445 nm) white light emission (WLED)was generated. The sintering temperature with fixed time (5 hours) for phosphor powder was optimized and found to be 1050 °C. The crystallinity structure, luminescent properties and chromaticity were characterized by X-ray diffraction (XRD), field emission-scanning electron microscope (FE-SEM), electroluminescence (EL) and standard CIE 1931 Chromaticity diagram. The results show that the obtained YAG:Ce+3 phosphor sintered at 1050°C has good crystallinity with pure phase, low agglomeration particles and strong yellow emission that offering daylight white LED with tuneable correlated color temperature (CCT) and a good colour rendering index (CRI) compared to those sintered at 950 °C, 850°C and non-sintered phosphor powders

The structural and dynamics neutron study of proton conductors: Difficulties and improvement procedures in protonated perovskite

With the expected development of Hydrogen as energy vector, there is a great impetus on the study of thermally stable proton conductors, the core of fuel cells, electrolysers and potential CO2 converters. Prior to a successful industrial application one should first well determine their extremely complex physical and chemical behaviour related to the unique character of the proton. The difficulties in comprehension of the nature of mobile protonic species, their location (especially the differentiation between bulk and surface species) as well as local and long range dynamics are different as a function of the hydration level: i) in hydrates the number of protons not really involved in the conduction is much larger than that of protonic conducting species, ii) in non-hydrated materials, the total amount of conducting protons can be very small, as dopants in semiconductors, and similar to that arising from surface water and physisorbed protonic moieties. The attempts and difficulties to locate and identify the protonic species and their dynamics using the neutron techniques are discussed in the light of representative examples, with emphasis on proton conducting perovskites