EPR investigations on europium(II)-doped barium aluminate

High frequency EPR spectra of europium(II)-doped BaAl2O4 powder phosphor have been analysed. Spectral simulation was carried out by a Fourier transform Monte Carlo method using an equation derived from the second-order perturbation of the energy levels for S=7/2. It is found that the spectra can best be interpreted in terms of europium(ii) ions in two different sites. One quarter of the europium(ii) ions are located in a site with a \D\ of 0.345 cm(-1), and the remaining europium(ii) ions are in a site with a \D\ of 1.08 cm(-1). Estimated values of \E\ are equal to 1/3 \D\ and are independent of the sites. From the comparison of these EPR parameters with the XRD crystallographic data we deduce that when europium is substituted for barium its surroundings give rise to rearrangement.