Luminescence and chromaticity of alkaline earth aluminate M_xSr_(1-x)Al_2O_4:Eu~(2+) (M: Ca,Ba)

摘要

In order to prepare fluorescent material for UV-LED used as illumination light source, two series of Eu~(2+) doped (1 mol%) alkaline earth aluminate phosphors Ca_xSr_(1-x)Al_2O_4 and Ba_xSr_(1-x)Al_2O_4 were prepared. The crystal structure, relative quantum efficiency(Qr), peak wavelength(λ_p), color tuning and chromaticity were investigated by XRD patterns and photoluminescence (PL) on samples prepared by solid solution system (s series) and powder mixing system (m series) respectively. For the s series, the synthesized Ca_xSr_(1-x)Al_2O_4:Eu~(2+) powders show that the structure transforms from monoclinic to hexagonal at x ≤ 0.5, and λ_p increases from 442.3 to 529.7nm with decreasing x. For the Ba_xSr_(1-x)Al_2O_4:Eu~(2+) system, the structure transforms from monoclinic to hexagonal at x ≥ 0.3, and λ_p decreases from 520.5 to 502.2 nm continuously from x = 0 to 1. The shift in λ_p could be explained by the crystal field effect, which is affected by different coulomb attractive forces due to the various fraction of alkaline earth cation in the host lattice. Different phosphor properties prepared by either solid solution or powder mixing methods were characterized by chromaticity measurements for both reflective and transmissive modes.