Luminescent properties of crystalline YAG:Ce for white LED applications
Performed is a comparative study of the characteristics of YAG:Ce luminescent converters with single-crystalline, cellular and polycrystalline structure obtained by the method of directed crystallization of the melt. Peculiarities of the structure and surface morphology of the converters are found to essentially influence their spectral characteristics and luminescence efficiency. It is shown that polycrystalline converters based on YAG:Ce are promising for application in white light emitting diodes.
Solid State Light Source Fabricated with YAG:Ce Single Crystal
A solid state, yellow-white emitting light source has been manufactured employing a YAG:Ce single crystal as a wavelength conversion material to analyze the conversion process quantitatively and also to explore the ultimate limit of the conversion efficiency. Excitation polarized coherent blue light is incident on to the crystal at the Brewster angle and is multiply reflected inside the crystal with internal total reflection. The generated light is shown to be efficiently extracted by providing a light guide with a suitable shape at the front surface of the crystal.
Growth and Characterization of β-RDX Single-Crystal Particles
1,3,5-Trinitrohexahydro-s-triazine (RDX) single-crystal particles crystallized in the β phase have been successfully grown by sublimation–recrystallization. Synchrotron X-ray diffraction results confirm that the recrystallized products are β-RDX single crystals. Compared to the traditional solution deposition methods, the sublimation method used in this work breaks through the mass limitations during the growth of β-RDX. The distribution of α- and β-RDX on different substrates reveals that hydrophilic substrates are prone to grow β-RDX single crystals and that hydrophobic substrates prefer α-RDX single crystals. The sublimation rate dominates the growth of pure β-RDX. The mechanisms of the phase transition from β-RDX to α-RDX during the process of sublimation–recrystallization have been studied. The current results can promote the potential application of β-RDX in the propellant, explosives, and military fields.