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Zhang X.,Hebei University of Technology | Zhang X.,Key Laboratory of Micro and Nano scale Boron Nitride Materials of Hebei Province | Lu Z.,Hebei University of Technology | Lu Z.,Key Laboratory of Micro and Nano scale Boron Nitride Materials of Hebei Province | And 12 more authors.
Journal of Materials Chemistry C | Year: 2015

The blue emitting BCNO phosphors with high quantum yields were prepared at 625 °C using boric acid, melamine and hexamethylenetetramine as raw materials. The BCNO phosphors have turbostratic boron nitride structure and consist of nanocrystallites 5 nm in size. The emission and excitation spectra can be tuned by the contents of raw materials and sintering temperatures. The quantum yields of BCNO phosphors can be up to 99% with increasing boric acid. The FTIR spectra suggested that the quantum yield can be improved with increasing strength of B-N and B-N-B bonds, and formation of B-O-B bonds, while it decreased with enhancement of CC bonds. The emission decay curves indicated that the decay process was related to two luminescence centers corresponding to carbon and oxygen impurities. In addition, the high temperature emission spectra disclosed that the nitrogen vacancy would participate in the blue light emission process at a certain heating temperature. The blue emitting BCNO phosphors with high quantum yields have great potential application in luminescence and display areas. This journal is © The Royal Society of Chemistry 2015.


Zhang X.,Hebei University of Technology | Zhang X.,Key Laboratory of Micro and Nano scale Boron Nitride Materials of Hebei Province | Jia X.,Hebei University of Technology | Jia X.,Key Laboratory of Micro and Nano scale Boron Nitride Materials of Hebei Province | And 12 more authors.
RSC Advances | Year: 2015

Red emitting (λem = 620 nm) BCNO phosphors were synthesized at 650 °C with solid state reaction method using boric acid and hexamethy lenetetramine as raw materials. The BCNO phosphors have turbostratic boron nitride structure and particle sizes are in micro scale. Carbon and oxygen elements were bonded to boron and nitrogen to form BCNO phosphors. The emission peaks were shifted from blue light (420-470 nm) to red light (590-620 nm) with increasing sintering temperature, heating time and the ratio of boric acid to hexamethy lenetetramine, which was induced by partially formed BCNO and completely formed BCNO phosphors. The decay curves and emission spectra indicated that the red emission was induced by two luminescence centers, corresponding to longer lifetime τ1 and short lifetime τ2. The ultraviolet visible absorption spectra disclosed that the optical band gap was changed from 1.75 eV to 2.0 eV with different preparation conditions. The high temperature emission spectra suggested that the nitrogen defects levels served as electron traps and attended the red emission. The luminescence mechanism of BCNO phosphors was stated by a simplified energy level diagram. The red emission BCNO phosphors have good thermal stability and great potential application on lighting, display, solar cell and biomedical fields. © The Royal Society of Chemistry 2015.


Zhang X.,Hebei University of Technology | Zhang X.,Key Laboratory of Micro and Nano scale Boron Nitride Materials of Hebei Province | Yu J.,Hebei University of Technology | Yu J.,Key Laboratory of Micro and Nano scale Boron Nitride Materials of Hebei Province | And 14 more authors.
Journal of Luminescence | Year: 2016

BCNO phosphors with Al3+ and Ti4+ doping were synthesized and their spectral properties were systematically investigated. The BCNO phosphors with Al3+ doping are mainly composed of amorphous Al2O3 and BCNO nanocrystal. The crystallinity of BCNO phosphors and intensity of B-N related chemical bonds are improved with Al3+ doping which leads to the enhancement of quantum yields from 5.6% to 63.4%. In addition, The BCNO phosphors with Ti4+ doping are consisted of TiO2 with anatase and rutile structures and BCNO nanocrystals. The emission spectra are red shifted from 510 nm to 555 nm with the increase of Ti4+ doping, and the excitation intensity is successfully improved by Ti4+ doping in a wide range of 400-500 nm, which is favorable for blue light excitation. Both the spectral properties and electron transition process can be explained by a simplified energy band diagram. The BCNO phosphors with Al3+ and Ti4+ doping can be good candidates for white LED with ultraviolet and blue light excitation. © 2016, Elsevier B.V. All rights reserved.

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