Energy levels of Dy3+(4f 9) in orthoaluminate crystals

Abstract

A detailed crystal-field splitting analysis is reported for the energy levels of ${\mathrm{Dy}}^{\text{3+}}{\text{(4f}}^9)$ in crystals of ${\mathrm{YAlO}}_3$ and ${\mathrm{DyAlO}}_3$ orthoaluminates. Experimental energy (Stark) levels for the 15 lowest-energy ${}^{\text{2S+1}}{L}_J$ multiplet manifolds of ${\mathrm{Dy}}^{\text{3+}}$ are reported and supplemented with values found in the literature. A parameterized Hamiltonian, including Coulombic, spin-orbit, configuration interaction, and crystal-field terms in $C_s$ symmetry, was diagonalized for the ${}^6{H}_J,$ ${}^6{F}_J,$ ${}^4{F}_J,$ ${}^4{I}_J,$ and ${}^4{G}_J$ states. Initial sets of crystal-field parameters were determined from lattice-sum calculations and the three-parameter theory. Considerable J-mixing is found for states having nearly the same energy such as the manifolds ${}^6{F}_{\text{11/2}},$ ${}^6{H}_{\text{9/2}},$ and ${}^6{F}_{\text{9/2}},$ ${}^6{H}_{\text{7/2}}.$ Even states that are well separated from each other in energy show sufficient J mixing to explain the polarized absorption and Zeeman effects that involve transitions from the nearly pure (less than 0.2% J mixing) ground state, ${}^6{H}_{\text{15/2}}$ to excited states such as ${}^6{F}_{\text{5/2}}$ and ${}^6{F}_{\text{3/2}}.$ The rms for 70 calculated-to-experimental Stark levels for ${\mathrm{Dy}}^{\text{3+}}$ in ${\mathrm{YAlO}}_3$ is 10 cm⁻¹; the rms for 43 calculated-to-experimental levels for ${\mathrm{Dy}}^{\text{3+}}$ in ${\mathrm{DyAlO}}_3$ is 8 cm⁻¹.