Crystal Field Determination in Rare‐Earth Oxysulfides. II. Optical Experiments for Ho³⁺ and Dy³⁺ Ions

Abstract

The crystal field levels of the ground state manifold of Ho3+ have been obtained from the luminescence spectrum of Yz02S:5~o Ho3+. The ground state of the Ho3+ ion is found to be a set of five levels (0, 8, 14, 18,23 cm-1). An attempt has been made t o deduce the parameters of the CEF Hamiltonian from the experimental level energies. For Dy3+, the breaking up of the fundamental 'H15/2 multiplet has been obtained by analysing the fluorescence spectrum of Y202S: 1% Dy3+ and the absorption spectrum of Dy20,S. The ground state is found to be a doublet relatively well separated (21 cm-1) from the first excited level. I n these two compounds, CEF calculations give satisfactory agreement with both the value and direction of the magnetic moment obtained from neutron diffraction experiments.Les niveaux de champ cristallin du multiplet fondamental &I8 dc l'ion Ho3+ ont BtB obtenues par l'analyse du spectre de luminescence de Y202S:5~0 Ho3+. L'btat fondamental est constitub d'un ensemble de 5 niveaux trhs serrbs (0, 8, 14, 18, 23 cm-l). Sur la base de ces rbsultats cxpbrimentaux, nous avons dCterminB les six parametres de I'hitmiltonien de champ cristallin. En ce qui concerne Dy3+, la dbcomposition du multiplet fondamental 6H15/2 a Btb dbduite du spectre de fluorescence de YzO,S: l"/b Dy3+ et d u spectre d'absorption du composb pur. L'btat fondamental est un doublet relativement bien sbparb (21 cm-l) du premier niveau excitb. Pour ces deux composbs, les calculs de champ cristallin sont en accord satisfaisant avec les rbsultats de diffraction neutroniqoe, en ce qui concerne la direction et la vnleir des moments magnbtiqries.

Crystal Field Determination in Rare‐Earth Oxysulfides III. Specific Heat Measurements on Gd, Tb, Ho, and Dy Oxysulfides

“…The results obtained by crystal field analysis [ 2 ] are, a t first sight, compatible with these specific heat data.…”

“…I n order to explain the low-temperature magnetic properties, a good knowledge of the crystal field effects on the R3+ ions is necessary. In papers I [l] and I1 [ 2 ] we reported the results of optical experiments performed on Tb, Ho, and Dy oxysulfides. Unfortunately these experiments did not lead to an unambiguous determination of the splitting of the ground state multiplet for these three ions, so we undertook heat capacity experiments in order to remove the ambiguities.…”