Effects of crystal structures on luminescent properties of Eu doped Ca–Al–O systems

To investigate the correlations between the structural transformations of calcium aluminates and luminescent properties, Eu doped Ca–Al–O system phosphors were synthesized by solid-state reaction process in H₂ atmosphere with CaCO₃, Al₂O₃, Eu₂O₃, and a flux, H₃BO₃ as starting materials. Various phases such as CaAl₂O₄, CaAl₄O₇, Ca₃Al₂O₆, and Ca₁₂Al₁₄O₃₃ were achieved depending on firing temperature, flux amounts, and the mixing ratio of CaO to Al₂O₃. Among various phases, only CaAl₂O₄ contributed to a strong blue emission at 440 nm with an excitation wavelength of 330 nm.