A Study on the Synthesis and Luminescence Properties of Some New Boronitride-Based Phosphors
For fabrication of white light light emitting diodes (LED), tis research is attempted to develop novel red-, green-, and blue-emitting boronitride phosphors with the excitation wavelength ranging from 350-460 nm. The boronitride phosphors were prepared by solid-state reactions and their crystal structure, phase purities, chromaticity and luminescence properties were characterized by powder X-ray diffraction, diffuse reflectance and photoluminescence spectra. Most of the as-synthesized boronitride phosphors were found to show self-activation. The rare earth ions were found to substitute and enter the cation site of the host with four to six in coordination. The Eu3+-doped phosphors were found to be mainly red-emitting. On the other hand, the luminescence of the Eu2+- and Ce3+-doped boronitride phosphors were found to emitting from yellow, blue to infrared and was highly dependent on the crystal field strength and covalency of the hosts, especially on the 5d orbital splitting and site symmetry of the Eu2+ and Ce3+ activators.
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