Local Structure of Europium‐Doped Luminescent Strontium Fluoride Nanoparticles: Comparative X‐ray Absorption Spectroscopy and Diffraction Study

Abstract

Rare‐earth based luminescent materials are key functional components for the rational design of light‐conversion smart devices. Stable Eu3+‐doped strontium fluoride (SrF2) nanoparticles were prepared at room temperature in ethylene glycol. Their luminescence depends on the Eu content and changes after heat treatment. The crystallinity of heat‐treated material increases in comparison with as‐synthesized samples. Particles were investigated in solution using X‐ray diffraction, small‐angle X‐ray scattering, and X‐ray spectroscopy. After heat treatment, the size of the disordered nanoparticles increases together with a change of their local structure. Interstitial fluoride ions can be localized near Eu3+ ions. Therefore, non‐radiative relaxation from other mechanisms is decreased. Knowledge about the cation distribution is key information for understanding the luminescence properties of any material.

Synthesis of SrF2:Yb:Er ceramic precursor powder by co-precipitation from aqueous solution with different fluorinating media: NaF, KF and NH4F

“…20 When obtaining powders of fluorides for the subsequent preparation of ceramics, various fluorinating agents (HF, KF, NaF, KHF 2 and NaHF 2 ) were proposed without systematic consideration of their effect on luminescence properties. The pro-duction of fluoride powders as precursors for ceramics narrows the variety of synthesis methods, since it excludes approaches involving organic compounds when using hydro/ solvothermal [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] and sol-gel [36][37][38][39] synthesis methods, which will lead to carbon contamination during annealing. Using the combustion method, 40,41 it is difficult to control the size and morphology of the resulting particles, which in turn affects the properties of the resulting ceramics and also introduces carbon.…”

Possibility to Apply Strontium Aluminate to Produce Light‐Emitting Plants: Efficiency and Safety

“…Promising orange‐red‐emitting materials for WLED production include calcium scandate (CaSc 2 O 4 (CSO)) and orthosilicate materials doped with Ce 3+ or Eu 2+ (CaSrSiO 4 : Eu 2+ ) [29,33] . In contrast, SrAl 2 O 4 , doped with Dy 3+ and Eu 2+ , is used to increase light intensity and prolong light emission [26] . Overall, the use of SrAl 2 O 4 in light‐emitting plants and WLEDs might offer sustainable lighting solutions, prolonged emission, increased light intensity, and high stability and efficiency, providing various benefits for both LEPs and WLEDs.…”

“…[29,33] In contrast, SrAl 2 O 4 , doped with Dy 3 + and Eu 2 + , is used to increase light intensity and prolong light emission. [26] Overall, the use of SrAl 2 O 4 in light-emitting plants and WLEDs might offer sustainable lighting solutions, prolonged emission, increased light intensity, and high stability and efficiency, providing various benefits for both LEPs and WLEDs.…”

“…It is known that the structure of SrAl 2 O 4 crystalizes consists of rings formed by six‐corner‐sharing oxide aluminate tetrahedra, which create channels where the Sr 2+ ions are situated [25] . Increased luminescence depends on the europium ion (Eu 2+ ) content, and changes after heat treatment lead to an increase in the crystallinity of the material [26] . Sr 2+ ions are replaced by Eu 2+ and dysprosium ion (Dy 3+ ).…”

“…[25] Increased luminescence depends on the europium ion (Eu 2 + ) content, and changes after heat treatment lead to an increase in the crystallinity of the material. [26] Sr 2 + ions are replaced by Eu 2 + and dysprosium ion (Dy 3 + ). The mechanism for the luminescence persistence of SrAl 2 O 4 : Eu 2 + , Dy 3 + arises from the charge transfer from oxygen to the Eu 2 + ion that occurs upon UV irradiation or visible light.…”