Stabilization of Eu²⁺ in Li₂B₄O₇ with the BO₃ network through U⁶⁺ co-doping and defect engineering

Abstract

Owing to the unique 4f-5d transition and involved of 5d electron, divalent europium (Eu2+) ion is extensively used as dopant ion in luminescent materials for phosphor converted light emitting diodes...

Local Structure and Speciation-Driven UO22+ → Sm3+ Energy Transfer for Enhanced Luminescence in Li2B4O7

“…The Raman spectra of the three samples displayed in Figure 1c consist of characteristic peaks of vibrational modes of B−O and Li−O bonds in a tetragonal LTB lattice. 23 The peaks around 164 and 199 cm −1 arise from the bending modes of the tetrahedral BO 4 units, and the vibrational modes of LiO 6 and LiO 4 units were observed at 255 and 489 cm −1 , respectively. The BO 4 symmetric and asymmetric stretching modes appeared at 507 and 778 cm −1 , with asymmetric deformation modes of trigonal BO 3 at 720 cm −1 , and BO 4 distortion modes were observed at higher frequencies (>1000 cm −1 ), respectively.…”

“…Raman spectroscopy was performed for LTB:0.5Sm 3+ and codoped LTB:Sm 3+ ,U samples. The Raman spectra of the three samples displayed in Figure c consist of characteristic peaks of vibrational modes of B–O and Li–O bonds in a tetragonal LTB lattice . The peaks around 164 and 199 cm –1 arise from the bending modes of the tetrahedral BO 4 units, and the vibrational modes of LiO 6 and LiO 4 units were observed at 255 and 489 cm –1 , respectively.…”

“…A red shift in all the Raman peaks of doped and codoped LTB samples was observed compared to the undoped LTB samples, which indicated the expansion of B−O and Li−O units in the LTB lattice. 23 Figure 1d shows the TEM images of a representative codoped LTB:0.5%Sm 3+ ,0.5%U sample with microparticles having polygon like morphology. Some particles were observed to have a elongated hexagon-like morphology (inset of Figure 1d).…”

“…Lithium tetraborate (Li 2 B 4 O 7 ) is one of the valuable hosts due to its wide band gap, higher chemical stability, simple and low-cost synthesis, and lower phonon energy. − Li 2 B 4 O 7 (LTB) has been explored for scintillators, radiation dosimeter, and solid-state neutron detection applications. , Additionally, the LTB host offers rich chemistry due to the presence of Li sites and both triangular BO 3 and tetrahedral BO 4 sites. Interestingly, the different O-coordination environments of activator ions at different crystallographic sites of LTB can be explored to achieve tunable emissions of Ln 3+ ions and different ET routes.…”

Utilizing Energy Transfer in Mn2+/Ho3+/Yb3+ Tri-doped ZnAl2O4 Nanophosphors for Tunable Luminescence and Highly Sensitive Visual Cryogenic Thermometry

“…The third positron lifetime in the range of ns is due to positronium formation on the surface of the crystallites in the powder samples. The intensity of this component is low in powder samples and is found to be higher if crystallite sizes are smaller . The intensity of the positronium component ( I 3 ) increased with dopants except when a small amount of Mn 2+ was codoped.…”