ESR of Gd3+ ions in potassium yttrium tungstate

The software in MATHLAB medium has been developed to model ESR spectra of paramagnetic centers in single crystals. By means of this program, the angular dependences of ESR spectra found in KY(WO4)2, potassium yttrium tungstate, doped with gadolinium were analyzed. The spectra analysis indicates that they are determined by the presence of Gd3+ ions with the electron spin S = 7/2 occupying the structural position of Y3+ ions in the crystal structure. Parameters of spin Hamiltonian were defined for the analyzed ESR spectrum of Gd3+. Unusual features of the analyzed ESR spectra have been discovered in the region of 9.5 GHz which remind by appearance SHF line. The researches made show the position of this line to correspond to the region of quasi-intersection of energetic levels, and along with the line shape it is most likely to reflect the peculiarities of the region in whose interval wave functions of the energetic levels undergo substantial modifications.