Electron paramagnetic resonance characterization of impurity Fe3+ ions in a PbWO4 single crystal

The electron paramagnetic resonance of the Fe3+ ion in a PbWO4 single crystal has been investigated with an X-band spectrometer at 4 K. The spectroscopic splitting tensor g and the zero-field splitting parameters Bqk were determined using the effective spin Hamiltonian. The rotation patterns in the crystallographic planes, together with the spin-Hamiltonian parameters, of the Fe3+ ion show that the local site symmetry around the Fe3+ ion in a PbWO4 crystal is orthorhombic even though the crystal structure of the PbWO4 unit cell is tetragonal. The energy levels of the ground state for an Fe3+ ion embedded in a PbWO4 crystal are calculated. It turns out that the Fe3+ ion substitutes for the W6+ ion in the oxygen tetrahedron without nearby charge compensation.