Effect of boric acid on structure,morphology and luminescent properties of divalent europium doped calcium aluminate phosphors

Blue phosphors Ca_1 − xAl₂O₄: xEu²⁺ were prepared by high temperature solid-state method. Their structure, morphology and luminescent properties were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM) and fluorescence spectroscopy. The effect of different amounts of fluxing agent H₃BO₃ on structure, morphology and luminescent properties of blue phosphors Ca_1 − xAl₂O₄: xEu²⁺ luminous intensity caused by different amount of H₃BO₃ was also investigated. The amount of H₃BO₃ doped Ca_1 − xAl₂O₄: xEu²⁺ in optimal luminous intensity had been determined. The results showed that both the excitation and emission spectra of samples were all broad bands, and that the peak of emission spectra was near 442 nm, which was corresponding to the 4f⁶5d → 4f⁷ transition of Eu²⁺ illuminating blue light. Ca_1 − xAl₂O₄: xEu²⁺ (x = 3.5 mol%) could be gained with good morphology and the best luminous intensity when H₃BO₃ mass ratio was 0.5 wt%.