Comparison of <scp>EPR</scp> spectra of the Gd³⁺ ion‐doped <scp>YA</scp>l₃(<scp>BO</scp>₃)₄, Eu<scp>A</scp>l₃(<scp>BO</scp>₃)₄, and Tm<scp>A</scp>l₃(<scp>BO</scp>₃)₄ single crystals

Abstract

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 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.