Combustion synthesis was explored as an alternate synthetic route to producing oxide phosphors with improved luminescent properties. The technique involves the highly exothermic reaction of metal nitrates (oxidizers) ...
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Combustion synthesis was explored as an alternate synthetic route to producing oxide phosphors with improved luminescent properties. The technique involves the highly exothermic reaction of metal nitrates (oxidizers) with an organic fuel (e.g., urea, carbohydrazide, glycine) at 500 °C. We have synthesized Tb3+, Eu3+, Tm3+ and Cr3+-activated Y3Al5O12 (YAG), Y2O3:Eu3+, and Y2SiO5:Ce3+ phosphors. As-reacted powders are well-crystallized, luminescent, and have a small particle size. The effects of processing parameters such as type of fuel and fuel/oxidizer ratio on the spectral energy distribution were determined using photoluminescence measurements. Low-voltage (100-1000 V) efficiency of combustion-synthesized phosphors was compared with efficiencies obtained for phosphors prepared via hydrothermal synthesis and high-temperature solid-state reaction.
We have demonstrated the operation of a fiber-optic device originally proposed to continuously measure the location of a shock front, but which also has potential for use as a crack location sensor. It consists of one...
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We have demonstrated the operation of a fiber-optic device originally proposed to continuously measure the location of a shock front, but which also has potential for use as a crack location sensor. It consists of one or a group of fibers uniformly doped along their length with neodymium, which fluoresces at about 1060 nm in response to being optically pumped at a shorter wavelength. In our case, the pump source was a laser diode emitting at 810 nm. As the length of the fiber is reduced, the strength of the fluorescence signal diminishes along with the number of fluorescing atoms. Laboratory and explosives experiments were performed on sensor fibers containing various concentrations of dopants. We also investigated the benefits, in an explosives application, of adding phosphorus to narrow the fluorescence line.
We have examined the optical bandgap, particle size distribution, photoluminescence spectra, and cathodoluminescent response of fifteen phosphors that contain transition-metal and main-group sensitizers. We determined...
We have examined the optical bandgap, particle size distribution, photoluminescence spectra, and cathodoluminescent response of fifteen phosphors that contain transition-metal and main-group sensitizers. We determined luminance versus applied voltage curves for electron energies from 5 to 1000 eV. Seven phosphors exhibit threshold voltages less than 110 V. Y1.96Eu0.04O3 exhibits a threshold voltage of 13 V and, at 300 V, displays a luminance of 25 fL and a luminous efficiency of 0.02 lm/W.
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