EPR ofGd3+in a single crystal of thorium oxysulfide

Abstract

The electron paramagnetic resonance of Gd3+ has been studied in a single crystal of thorium oxysulfide. The experimental results are interpreted using a spin Hamiltonian for tetragonal symmetry, and the crystal-field parameters and the g factor are determined. The very good agreement between the calculated and experimental data shows that the Gd + ion enters substitutionally, and that the charge compensation is far enough away to avoid any distortion of the local symmetry.

Superposition Model Analysis of the Spin Hamiltonian Parameters of Two Gd3+ Doped Thorium Dichalcogenides

“…Taking into account that the ligand distances are shorter in ThOS than in ThS2, it is not unlikely that the substitution of a tetravalent ion, as Th 4+ , with the trivalent Gd 3+ may lead to an enlargement of the negative ligand cage, as a consequence of the smaller positive charge at the center. On the other side, this distortion must be such that it does not modify the site symmetry, which remains the same after the introduction of the impurity, as shown by the EPR spectra [11]. In terms of polar coordinates, this means that the angle cp must remain unchanged for every ligand, w r hile R and 6 (except for Sn) can vary.…”

“…The experimental spin Hamiltonian second degree parameters [11,13] for both compounds are shown in Table 3.…”

“…Both crystals, TI1S2 and ThOS, were grown at the Karlsruhe European Institute for Transuranium Elements, by means of a transport method already described [11]. Following the data of Zachariasen [12], the TI1S2 crystal belongs to the space group Pmnb-Doh an d has the same structure as PbCl2, with lattice parameters a -4.259(2)1, b = 7.249(3) Ä and c = 8.600 (3) Ä.…”

Spin-Lattice Relaxation and Superposition Model Calculation in Gd3+-Doped LiErF4and LiDyF4Crystals

“…The x and y axes are assumed to be in the plane perpendicular to the z axis in correspondence to equivalent positions of the maximal overall splitting in the xy plane (see angular variation in the xy plane [24]). On the other hand, assuming the x and y axes considered positions of the minimal overall splitting in the xy plane [24] and fitting the experimental data in the zxmin plane, the same absolute values (in error bars), but the opposite signs should be obtained only for b44a n d b 4 6 spin-Hamiltonian parameters [25], as compared to parameters obtained from the fitting of the experimental data in the rmax plane; e.g., from the experimental data measured in the zxmin plane for LiErF4 one evalua t e d b 4 4 = -0 . 4 5 f 0 .…”

EPR of Gd3+ in a Single Crystal of Thorium disulfide (ThS2)

“…In a preceding paper [1], we have reported the EPR study on a Gd 3+ doped single crystal of Thorium oxysulfide (ThOS). Following this line of research, we present in this work the results of the EPR study on a Gd 3+ doped single crystal of Thorium disulfide (TI1S2).…”