Europium (II) Sulfate EuSO₄: Synthesis Methods, Crystal and Electronic Structure, Luminescence Properties

Abstract

In the present work, we report on the synthesis of EuSO4 powders by two different methods using EuS as starting material. The compound EuSO4 contains divalent europium and crystallizes in the orthorhombic crystal system, space group Pnma with parameters close to SrSO4. The compound exhibits near isotropic thermal expansion over the temperature range 300–700 K. EuSO4 was examined by Raman, Fourier‐transform infrared absorption and luminescence spectroscopy methods. EuSO4 is found to be an indirect bandgap material with a bandgap close to direct electronic transition. The emission lifetime of divalent europium d‐f emission in EuSO4 shows an unusual behavior for stoichiometric compounds, as it shortens upon cooling from 1.11(1) μs at room temperature to 0.44(1) μs at 77 K.

Single-Bubble Sonoluminescence of Colloidal Suspensions of Europium(II) Salt Nanoparticles

“…24 As can be seen from our data, SO 4 2provides the shortest wavelength luminescence maximum among Eu 2+ compounds with the studied ligands. Considering the bidentality of the sulfate ion and shorter bond lengths Eu-O (2.521 and 2.657 Å) 22 compared to Eu-Cl (3.095 Å) or Eu-Br (3.163 Å), the effect of SO 4 2on the PL spectrum can also be explained in terms of the approach proposed in Galimov et al 24 Figures 1b-3b show the obtained SBSL (curve 2) and m-SBSL (curve 1) spectra of colloidal suspensions of europium salts in dodecane. These spectra contain a structureless wide band of the emission continuum of a nonequilibrium bubble plasma with a monotonically decreasing intensity from the ultraviolet (UV) to the infrared region of the spectrum.…”

“…The EuSO 4 was synthesized from EuCl 3 •6H 2 O crystalline hydrate (99.99%, Lanhit Ltd.) by reducing Eu 3+ → Eu 2+ in the Jones reducer according to the known method. 22 Suspensions of europium salt nanoparticles were prepared by adding 0.1 g of large-sized (10-300 μm) crystals of Eu 2+ salts to dodecane (Acros Organics, 20 mL) or to bidistilled water (in the case of water-insoluble EuSO 4 ) followed by ultrasonic treatment on a UZDN-2T disperser (ultrasound frequency 22 kHz, power 30 W, immersed titanium waveguide) for 1.5 h. The final fractions of suspensions containing nanoparticles no larger than 50 nm were obtained by filtration through an MFAS-1B membrane filter. The size distribution of nanoparticles was recorded by laser scattering on a Shimadzu Sald-7101 instrument.…”

Europium(ii) bis[tetrafluoro-2-(pentafluoroethoxy)ethanesulfonate] – structure and spectroscopic properties of a new near-UV emitter

“…in near the UV region, has one of the shortest wavelengths reported for 5d -4f luminescence occurring in Eu(II) systems, as the typical luminescence of the Eu 2+ cation is blue, sometimes green 13 and on rather rare occasions yellow. 45,46 To the best of the author's knowledge, no organic Eu(II) complex has been reported as a UV emitter; such emission has been so far found in EuSO 4 47 (382 nm at 77 K) or in some inorganic matrices (e.g. in a-CaAlF 5 -387 nm, b-CaAlF 5 -385 nm, 48 LiCaAlF 6 -371 nm or Ba(PO 3 ) 2 49 ).…”

“…This value is within the range observed for other Eu(II) compounds. For comparison purposes the following systems may be invoked: Eu-dotp complex 26 -biexponential decay with t 1 = 0.14 and t 2 = 0.61 ms; aqua(ethylenedisulfonato)europium(II) 28 -biexponential, t 1 = 0.070(10) ms and t 2 = 0.260 (10) ms; [Eu(12-crown-4)(H 2 O) 3 Cl] +18 -monoexponential, t = 0.505(5) ms; [Eu(15-crown5) 2 ] 2+18 -monoexponential, t = 0.745 (18) ms; [Eu(benzo-15-crown-5) 2 ] 2+16 -monoexponential, t = 0.59(1) ms; EuSO 4 47 -biexponential, t 1 = 0.130(3) ms and t 2 = 0.514(2) ms.…”

Negative Thermal Expansion in the Polymorphic Modification of Double Sulfate β-AEu(SO4)2 (A–Rb+, Cs+)

“…Compounds of rare-earth elements with tetrahedral anions attract researchers’ attention as they exhibit many interesting properties. − In recent years, more and more attention is paid to simple and complex sulfates as functional materials. Among them are phosphors, − catalysts, − and gas adsorbents. − The decisive aspects of the functionalization of rare-earth sulfates are such issues as polymorphism, isomorphism, and crystal-chemical transformations in the technological processes. − …”