Preparation And Optical Properties Of Boron Nitride Based Non-Rare Earth Phosphors

Organic fluorescent dyes,i.e.rhodamine B（RhB）,acridine orange（AO）,fluorescein isothiocyanate（FITC）,are low-cost and efficient non-rare earth phosphors and may be used in light-emitting diode（LED）.However,its luminescence can be easily quenched due to the aggregation of dyes.Another drawback of this material is the poor thermal stability.Encapsulation of organic fluorescent dyes into some porous materials is an effective strategy to improve the thermal stability and decrease the aggregation-caused quenching of dyes.In this study,inspired by the excellent chemical inertness and oxidation resistance,as well as optically transparency of porous boron nitride（BN）,RhB and AO fluorescent dyes incorporate into porous BN to prepare organic-inorganic composite fluorescent powder,and characterized its structure and properties.Firstly,hierarchically porous BN was successfully prepared by the high temperature heat treatment technology in N₂ using boric acid,urea and melamine foam as boron source,nitrogen source and hard template.Effects of various reaction conditions including reaction temperature,raw material ratio and template on the formation of hierarchically porous BN were studied.When the molar amount of urea was 3 times that of boric acid,hierarchical multilayer structure BN with a large number of open pores could be synthesized at 1100℃ under nitrogen by using melamine foam as template.In addition,the BN with graded multilayer structure has wide fluorescence emission and strong emission intensity.The BN prepared by this method has potential applications in packaging materials,fluorescent materials,catalyst carriers and other fields.Secondly,two novel non-rare earth BN/RhB and BN/AO organic-inorganic composite phosphors were synthesized by loading of RhB dyes and AO dyes into porous BN.The effects of the amount of RhB and AO dyes and annealing temperature on the optical properties of BN/RhB and BN/AO composite phosphors were discussed.The confinement of RhB dyes within porous BN can effectively restrict the dye aggregation and increase their red emission intensities.Besides,The strong interaction between dyes and BN is very important for maintaining the good thermal stability of the composites.The emission colors can be tuned by annealing of RhB@BN composites at different temperatures in air.In particular,when the amount of RhB and AO dyes added is 6 mg/L and 15 mg/L,respectively,the BN/RhB and BN/AO composite phosphors after 200℃ and 250℃annealing treatment exhibit strong fluorescence emission.