Synthesis and Characterization of CaAl2O4:Eu2+,Nd3+ Phosphors

The details of our experimental methods have been described previously[28 (link)]. Briefly, all CaAl₂O₄:Eu²⁺, Nd³⁺ powder samples were synthesized by a high-temperature solid-state reaction. High-purity SrCO₃, Eu₂O₃ (Rhône-Poulenc, 99.99%), Nd₂O₃, Al₂O₃, MCO₃ (M = Ca, Sr, and Ba; Merck, >99.0%), and SiO₂ (Aerosil OX 50, Degussa) were mixed and H₃BO₃ was added as a flux. After grinding the mixtures in an agate mortar, they were fired in molybdenum crucibles for 3–5 h at ~1300°C in a furnace under a weak reductive atmosphere of flowing N₂/H₂ (5%) gas. After cooling down the synthesized samples to room temperature, they were ground again in an agate mortar. The final samples were irradiated with 365 nm UV-light for 5 min. After turning off the UV lamp, the emission spectra were recorded with a Hitachi 850 fluorescence spectrophotometer in the wavelength range from 300 to 950 nm.