EPR Studies of Tb ⁴⁺ in Single Crystals of Zircon and Scheelite Structure Silicates and Germanates

Abstract

In memoriam Professor Gerhard LehmannElectron paramagnetic resonance spectra of tetravalent terbium ions have been observed in host crystals of ZrSi0 4 , HfSi0 4 , ThSi0 4 , ThGe0 4 (zircon structure) and ZrGe0 4 , HfGe0 4 (scheelite structure) at X band and Q band and various temperatures. The spin Hamiltonian parameters have been determined from the rotational diagrams; the zero field splittings turned out to be extremely large, so that complex spectra far from the strong magnetic field limit had to be analyzed. In all the compounds Tb 4+ substitutes for the tetragonal metal lattice sites. The incorporation of terbium, the origin of the large second-order parameters and comparisons with the spectra of trivalent gadolinium in similar systems are discussed.

Electron paramagnetic resonance study of rare-earth related centres in K2YF5:Tb3+ thermoluminescence phosphors

“…Extra confirmation of our identification of T1 and T2 as Tb 4+ centres comes from a limited number of literature reports on Tb 4+ in oxide crystals [18][19][20][21][22][23][24]. In these papers, the secondorder ZFS parameters for Tb 4+ centres were found to be typically an order of magnitude larger than those for Gd 3+ centres in the same (or very similar) environments.…”

Photochromism of doped terbium gallium garnet

“…Besides Ce 3+ ͑Ce 4+ is not paramagnetic͒ oxygen vacancies with one trapped electron ͑F + center͒ and Tb 4+ ions are possible candidates. Tb 4+ is an f 7 ion with an 8 S 7/2 state and an important admixtures from higher energy states which might lead to EPR signals with strongly varying effective g factors depending on the ligand fields and the microwave frequency used ͑see e.g., [23][24][25][26] ͒, so there is a fair chance that one of the ODMR signals for the 420 nm band observed by Reyher et al may also be attributed to Tb 4+ . In their ODMR spectra ͑Fig.…”

Molecular Complex of Tb in the +4 Oxidation State

“…The differences in the spectra of the Gd 3+ and Tb 4+ complexes may be ascribed in part to differences in the 1-Ln and 2-Ln structures and the increased ZFS resulting from the more charged Tb 4+ ion. 18 Magnetic susceptibility measurements as a function of temperature were performed on crushed crystalline samples of the 4f 8 1-Tb and the 4f 7 complexes, 2-Tb and 1-Gd, Figure 4. The χ M T = 7.78 and 7.77 emu•K/mol measured at 294 K for 1-Gd and 2-Tb, respectively, are in agreement with the χ M T = 7.88 emu•K/mol predicted for a 4f 7 complex by a first approximation using LS coupling for a 4f 7 ion (L = 0, S = 7/ 2), 6a and both are significantly lower than the 11.2 emu•K/mol observed for 4f 8 Tb 3+ in 1-Tb (predicted 11.8 emu•K/mol, L = 3, S = 5/2).…”