Comparison of EPR spectra of the Gd~(~(3+)) ion-doped YAl_3(BO_3)_4, EuAl_3(BO_3)_4, and TmAl_3(BO_3)_4 single crystals

摘要

The EPR spectra of Gd~(3+) ion replacing Y~(3+) or rare-earth (RE) ions in aluminum borates REAl_3(BO_3)_4 (RE=Y~(3+), Eu~(3+), Tm~(3+)) have been studied. The spin-Hamiltonian parameters of an impurity Gd~(3+) ion in these crystals were determined. The basic atom coordinates in the structure of TmAl 3 (BO_3)_4 crystal have been established. Distortions of the Gd~(3+) ion nearest environment were analyzed within the framework of the superposition model of zero-field splitting. The b_2~0 parameter change in isomorphic aluminum borates is shown to be determined by change of the angle between the Gd~(3+)-O~(2-) bond and the C_3-axis.