Preparation optimization and spectral properties of BCNO phosphors with high quantum efficiency

BCNO phosphors with high quantum efficiency (QE) were synthesized using trimethyl borate, melamine and urotropine as raw materials. The effects of urotropine, starting materials ratio, sintering time and temperature on luminescence properties were systematically investigated and the preparation conditions were optimized. The BCNO phosphor has turbostratic boron nitride structure and its size in the range of several millimeters. The emission peak position was not influenced by the content of urotropine. However, the emission peak blue can be tuned from 475 nm to 535 nm with increasing B/N source ratios (RB/N=2-6), while the QE decreased from 65.2% to 15.8%. The emission peaks of BCNO phosphor with RB/N=4 were in the range of green light (495-540 nm) with high QE (20.8-51.4%) as sintering time increased (4-20 h). In addition, the emission peaks of BCNO phosphor with RB/N=4 blue-shifted from 525 nm to 460 nm and increased QE (16.1-56.7%) with increasing sintering temperature (650-750 °C). The formation mechanism of BCNO phosphors was investigated by means of ultraviolet visible absorption spectra and infrared spectra. The tunable emission spectra and high QE corresponded to the chemical composition, carbon concentration and crystallinity of BCNO phosphors.