High frequency EPR investigations of gadolinium(III)-doped strontium aluminates

The high frequency EPR spectra of SrAl2O4 doped with gadolinium(iii) as a probe are discussed, focusing on the sites occupied by the lanthanides. This is because the emission due to europium(ii) of SrAl2O4:Eu,Ln (Ln: lanthanides) is significantly affected by such substitution. The EPR spectrum of SrAl2O4:Dy,Gd showed a pattern typical for two overlapping resonances of S-8(7/2) state ions with a lambda=\D/E\ of 1/3, suggesting that the gadolinium(III) sites have very low symmetry. From a comparison of the experimental and simulated EPR spectra it was found that both gadolinium(III) and europium(II) ions occupy strontium sites.