Theoretical studies of the spin‐Hamiltonian parameters for Er³⁺ in CaWO₄ and SrWO₄

Abstract

The spin-Hamiltonian parameters g factors g ʈ , g ⊥ and hyperfine structure parameters A ʈ and A ⊥ for Er 3+ ( 167 Er) in CaWO 4 and SrWO 4 are theoretically studied by using the perturbation formulas of the spinHamiltonian parameters for a 4f 11 ion in tetragonal symmetry. In these formulas, the contributions to the spin-Hamiltonian parameters arising from the second-order perturbation terms and the admixture of various states are considered. The crystal-field parameters for the tetragonally distorted tetrahedra are calculated from the superposition model and the local structural data of the impurity Er 3+ ions at the host Ca 2+and Sr 2+ sites. The theoretical parameters are in agreement with the experimental values. The validity of the results is discussed.

The synthesis and photoluminescent properties of calcium tungstate nanocrystals

“…Because of its superior luminescence properties CaWO 4 has been extensively used as blue phosphor (433 nm) in oscilloscopes and fluorescent lightening and as a scintillator for detecting X-rays and grays in medical applications [8,9]. This material doped with rare-earth ions has optical and laser properties [10,11]. Nanometer-scale calcium tungstate may play an essential role for its applications in future luminescent nanodevices.…”

Theoretical Investigation of the EPR G-Factor for the Axial Symmetry Ce3+ Center in the BaWO4 Single Crystal

“…First, the calculated intrinsic parameters fulfills inequality A 2 (R 0 ) A 4 (R 0 ) A 6 (R 0 ), where A 2 (R 0 ) is order 600 [cm −1 ], and A 6 (R 0 ) has a value of a few [cm −1 ]. Wu Shao-Yi et al set the values of intrinsic parameters A 2 (R 0 ) ≈ 400, A 4 (R 0 ) ≈ 50, A 6 (R 0 ) ≈ 17 cm −1 for Er 3+ centers in BaWO 4 , CaWO 4 , and SrWO 4 crystals [25,33]. H.G.…”

“…We have found only one paper focused on rare-earth centers, this is Er 3+ centers, in BaWO4 single crystals [25] and one other about similar, tetragonal Ce 3+ centers in YPO4 and LuPO4 crystals [26]. However, one can find that there are several papers about: (a) Ce 3+ and Yb 3+ in garnets [27][28][29], (b) Ce 3+ , Yb 3+ in YF3 crystal and Ce 3+ in fluoride ligands [30,31], (c) Yb 3+ in CaWO4 crystal [32], (d) Er 3+ in CaWO4 and SrWO4 crystals [33], Er 3+ in zircon-type compounds [34] or Er 3+ in PbMoO4 and SrMoO4 [35], Er 3+ at the Th 4+ site in ThGeO4 [36], (e) Nb 3+ , Yb 3+ in double tungstate's and molybdates [37], (f) color centers in BaWO4 [38,39] and others [40,41]. All these papers are focused on analysis of spin-Hamiltonian parameters for the rare-earth ion surrounded by oxygen's [ReO8] or fluoride's dodecahedrons [ReF8].…”

Investigation of the Spin Hamiltonian Parameters of Yb3+ in CaWO4 Crystal

“…Considering the local lattice relaxation due to the size mismatch, R j can be reasonably estimated from the approximate formula [5] …”