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.