Cubic-Site EPR Spectra ofEu2+andGd3+in MgO Single Crystals

Abstract

The electron-paramagnetic-resonance spectra of ${\mathrm{Gd}}^{3+}$ and ${\mathrm{Eu}}^{2+}$ in cubic sites of MgO single crystals have been observed. Spin-Hamiltonian parameters for these ions have been determined as a function of temperature. The observed variation of the fourth-order spin-Hamiltonian parameter $c$ vs lattice constant for the alkaline-earth oxides implies that in MgO overlap and covalency must be considered in determining the ground-state splitting of these ions.