Influence of interstitial UO₂²⁺ doping on the valence control of Eu and energy transfer to substitutional Eu³⁺ and Sm³⁺ in SrBPO₅

Abstract

Controlling valence mixing of Eu3+/Eu2+ and energy transfer between activator ions in solid solution is an important direction to improve efficiency and specificity of phosphors. In this work, structural and...

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

“…Based on the earlier report by Vinodkumar et al, 47 uranyl ions prefer to localize at interstitial positions.…”

“…The formation of vacancies can be explained by following equations:Based on the earlier report by Vinodkumar et al , 47 uranyl ions prefer to localize at interstitial positions.In reducing conditions, there could be the transient formation of U 5+ in LTB. The vacancies are present near by virtue of uranyl-Eu 3+ interactions that facilitate the transfer of electrons from uranium to Eu 3+ .…”

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

“…PLE spectra monitored at 524 nm (Figure a) emission from the uranyl moiety consisted of different bands located in the range of 240–360 nm which is characteristic of ligand to metal charge transfer (LMCT) between equatorial O 2– ligands (O eq ) and uranium­(VI) ions. The weak 400–440 nm band on the other hand can be assigned to forbidden LMCT from axial oxygen (O ax ) of uranyl (OUO) to U (VI) ions and the splitting is observed due to vibronic transitions. ,, The vibrational fine structure observed in PLE spectra (Figure b) originated from coupled symmetric stretching vibrational modes of uranyl with electronic transitions. The vibronic progression appeared between the lowest vibrational level of the ground state and the successive excited states.…”

“…The 5 D 0 energy levels of Eu 3+ emissive states (∼20,000 cm −1 ) which resulted in effective sensitization. 15,17,19,20 Wang et al have investigated the 4f/5f energy transfer between actinide (uranyl (VI)) and lanthanide (III) centers in europium-incorporated uranyl coordination polymers. 21 A tunable 4f/5f bimodal emission was reported for the first time in heterobimetallic compounds.…”

Uranium-Sensitized Luminescence Enhancement in Li2B4O7:U6+,Eu3+ and Potential Application towards Color-Tunable Phosphors and Actinide Sensor

“…26 The same group also reported interesting results in SrBPO 5 , wherein it was mentioned that uranium codoping influences the Eu 2+ /Eu 3+ ratio and accordingly the photophysical properties. 8 The white LEDs that are available in the market consist of yellow phosphor (e.g., Y 3 Al 5 O 12 :Ce 3+ ) and InGaN blue LED chips that have a wavelength range from 450 to 470 nm. 27 There is a lack of red-emitting phosphor in existing commercial white LEDs, and that is why it has a high correlated color temperature (CCT > 4500 K) and lower color rendering index (CRI, Ra < 75).…”