EPR of Dy3+ions in YAl3(BO3)4and EuAl3(BO3)4aluminoborates

The EPR spectra of impurity Dy3+ ions in YAl3(BO3)4 and EuAl3(BO3)4 aluminoborates were investigated. The signals from the ground and excited doublets were observed and the g-factors and the hyperfine interaction constants were determined. From the temperature dependence of the signal intensity of the excited doublet, the energy distances between the ground and excited doublets were obtained as (3.26 ± 0.13) cm–1 and (2.54 ± 0.16) cm–1 for YAl3(BO3)4 and EuAl3(BO3)4, respectively. A broadening of the absorption line with increasing temperature is related with the strong spin-phonon interaction and is described by the Orbach–Aminov process via the excited doublet. It was found that the decrease in g-factor is caused by the spin-phonon interaction.