Synthesis and Crystal Structure of the Short LnSb2O4Br Series (Ln = Eu–Tb) and Luminescence Properties of Eu3+-Doped Samples

Abstract

Pale yellow crystals of LnSb2O4Br (Ln = Eu–Tb) were synthesized via high temperature solid-state reactions from antimony sesquioxide, the respective lanthanoid sesquioxides and tribromides. Single-crystal X-ray diffraction studies revealed a layered structure in the monoclinic space group P21/c. In contrast to hitherto reported quaternary lanthanoid(III) halide oxoantimonates(III), in LnSb2O4Br the lanthanoid(III) cations are exclusively coordinated by oxygen atoms in the form of square hemiprisms. These [LnO8]13− polyhedra form layers parallel to (100) by sharing common edges. All antimony(III) cations are coordinated by three oxygen atoms forming ψ1-tetrahedral [SbO3]3− units, which have oxygen atoms in common building up meandering strands along [001] according to {[SbO2/2vO1/1t]–}∞1 (v = vertex-sharing, t = terminal). The bromide anions are located between two layers of these parallel running oxoantimonate(III) strands and have no bonding contacts with the Ln3+ cations. Since Sb3+ is known to be an efficient sensitizer for Ln3+ emission, photoluminescence studies were carried out to characterize the optical properties and assess their suitability as light phosphors. Indeed, for both, GdSb2O4Br and TbSb2O4Br doped with about 1.0–1.5 at-% Eu3+ efficient sensitization of the Eu3+ emission could be detected. For TbSb2O4Br, in addition, a remarkably high energy transfer from Tb3+ to Eu3+ could be detected that leads to a substantially increased Eu3+ emission intensity, rendering it an efficient red light emitting material.

New Crystal Structures of Rare‐Earth Metal(III) Oxotellurates(IV) RE2Te3O9: A1‐Type (RE=La, Ce) and A2‐Type (RE=Pr, Nd)

“…The major advantage of using oxotellurates(IV) as host material is the fact, that the doped cation has not to be excited directly (usually in a very small energetic range), but the excitation can also take place in the region of the broad O−Te charge‐transfer band and/or on the lone‐pair electrons at the Te 4+ cations, providing the so‐called “inorganic antenna effect” [55] . Therefore an enhanced luminescent efficacy is expected to be observed, just like in the case of the rare‐earth metal(III) oxoantimonate(III) bromides RE Sb 2 O 4 Br ( RE =Eu−Tb), [56] where Sb 3+ plays a similar role as its isoelectronic Te 4+ neighbour in the periodic system of the elements (PSE).…”

Synthesis, crystal structures and spectroscopic properties of pure YSb2O4Br and YSb2O4Cl as well as Eu3+- and Tb3+-doped samples

“…Common for both structures, the Sb 3+ cations form c 1 -tetrahedral [SbO 3 ] 3À units with three oxygen atoms and the electron lone pair, but this is the only common feature, since in both structures they are linked differently to each other to achieve {[SbO 2 ] À } motifs. In YSb 2 O 4 Br, their arrangement is already known from the representatives RESb 2 O 4 Br (RE ¼ Eu-Dy), 3,[21][22][23] namely the linkage via two corners to form onedimensional innite chains according to the Niggli formula Since the yttrium cations are surrounded by oxidoantimonate layers, an energy transfer from these layers towards any cation doped on the yttrium site could be expected. This was veried via luminescence spectroscopy (Fig.…”

Rare Earths Doped Materials

“…Photoluminescence studies of Eu 3+ -doped GdSb 2 O 4 Br and TbSb 2 O 4 Br showed efficient sensitization of the Eu 3+ emission, proving that Sb 3+ is an efficient sensitizer for Ln 3+ emission. For TbSb 2 O 4 Br, a remarkably high energy transfer from Tb 3+ to Eu 3+ was detected that led to a substantially increased Eu 3+ emission intensity, showing it can be an efficient red light-emitting material [4].…”

“…All publications in this Special Issue are original contributions. Different materials doped with Rare Earth Elements are presented in the publications, among them nanoparticles of Zr 1-x Eu x O 2-0.5x [1], fluoridated hydroxyapatite [2], Bi 12 GeO 20 sillenite bulk crystals [3], GdSb 2 O 4 Br, TbSb 2 O 4 Br [4], and LuVO 4 [5].…”

“…Pale yellow crystals of LnSb 2 O 4 Br (Ln = Eu -Tb) were synthesized via high-temperature solid-state reactions by Goerigk et al [4]. Photoluminescence studies of Eu 3+ -doped GdSb 2 O 4 Br and TbSb 2 O 4 Br showed efficient sensitization of the Eu 3+ emission, proving that Sb 3+ is an efficient sensitizer for Ln 3+ emission.…”