Sol-gel-derived transparent silica-(Gd,Pr)PO4 glass-ceramic narrow-band UVB phosphors

摘要

Silica-based monolithic transparent glass-ceramics containing (Gd,Pr)PO4 orthophosphate nanocrystals, prepared by a cosolvent-free sol-gel method, efficiently emit narrow-band ultraviolet B (UVB) photo-luminescence (PL) at similar to 313 nm from the P-6(7/2) - S-8(7/2) transition of Gd3+ ions upon excitation into the 4f-5d transition of Pr3+ ions. The formation of (Gd,Pr)PO4 nanocrystals as small as similar to 5-10 nm facilitates energy transfer between rare-earth (RE) ions while avoiding optical loss by Rayleigh scattering. Unlike conventional phosphors, the aggregation of Gd3+ ions causes no concentration quenching, and the incorporation of inert RE ions to block energy transfer, such as La3+ and Y3+ ions, is unnecessary. A glass-ceramic with a Pr3+ ion fraction of 0.02 exhibited the maximum internal and external PL quantum efficiencies of similar to 0.98 and similar to 0.91, respectively, under excitation at 220 nm.