Europium-Doped Ceria-Gadolinium Mixed Oxides: PARAFAC Analysis and High-Resolution Emission Spectroscopy under Cryogenic Conditions for Structural Analysis.

Title Europium-Doped Ceria-Gadolinium Mixed Oxides: PARAFAC Analysis and High-Resolution Emission Spectroscopy under Cryogenic Conditions for Structural Analysis.
Authors S. Chemura; T. Haubitz; P.A. Primus; M. Underberg; T. Hülser; M.U. Kumke
Journal J Phys Chem A
DOI 10.1021/acs.jpca.0c03188
Abstract

Gadolinium-doped ceria or gadolinium-stabilized ceria (GDC) is an important technical material due to its ability to conduct O ions, e.g., used in solid oxide fuel cells operated at intermediate temperature as an electrolyte, diffusion barrier, and electrode component. We have synthesized CeGdO:Eu (0 ? ? 0.4) nanoparticles (11-15 nm) using a scalable spray pyrolysis method, which allows the continuous large-scale technical production of such materials. Introducing Eu ions in small amounts into ceria and GDC as spectroscopic probes can provide detailed information about the atomic structure and local environments and allows us to monitor small structural changes. This study presents a novel approach to structurally elucidate europium-doped CeGdO:Eu nanoparticles by way of Eu spectroscopy, processing the spectroscopic data with the multiway decomposition method parallel factor (PARAFAC) analysis. In order to perform the deconvolution of spectra, data sets of excitation wavelength, emission wavelength, and time are required. Room temperature, time-resolved emission spectra recorded at ? = 464 nm show that Gd doping results in significantly altered emission spectra compared to pure ceria. The PARAFAC analysis for the pure ceria samples reveals a high-symmetry species (which can also be probed directly via the CeO charge transfer band) and a low-symmetry species. The GDC samples yield two low-symmetry spectra in the same experiment. High-resolution emission spectra recorded under cryogenic conditions after probing the D-F transition at ? = 575-583 nm revealed additional variation in the low-symmetry Eu sites in pure ceria and GDC. The total luminescence spectra of CeO:Eu showed Eu ions located in at least three slightly different coordination environments with the same fundamental symmetry, whereas the overall hypsochromic shift and increased broadening of the D-F excitation in the GDC samples, as well as the broadened spectra after deconvolution point to less homogeneous environments. The data of the Gd-containing samples indicates that the average charge density around the Eu ions in the lattice is decreased with increasing Gd and oxygen vacancy concentration. For reference, the Judd-Ofelt parameters of all spectra were calculated. PARAFAC proves to be a powerful tool to analyze lanthanide spectra in crystalline solid materials, which are characterized by numerous Stark transitions and where measurements usually yield a superposition of different contributions to any given spectrum.

Citation S. Chemura; T. Haubitz; P.A. Primus; M. Underberg; T. Hülser; M.U. Kumke.Europium-Doped Ceria-Gadolinium Mixed Oxides: PARAFAC Analysis and High-Resolution Emission Spectroscopy under Cryogenic Conditions for Structural Analysis.. J Phys Chem A. 2020. doi:10.1021/acs.jpca.0c03188

Related Elements

Cerium

See more Cerium products. Cerium (atomic symbol: Ce, atomic number: 58) is a Block F, Group 3, Period 6 element with an atomic weight of 140.116. The number of electrons in each of cerium's shells is 2, 8, 18, 19, 9, 2 and its electron configuration is [Xe]4f2 6s2. Cerium Bohr ModelThe cerium atom has a radius of 182.5 pm and a Van der Waals radius of 235 pm. In its elemental form, cerium has a silvery white appearance. Cerium is the most abundant of the rare earth metals. It is characterized chemically by having two valence states, the +3 cerous and +4 ceric states. The ceric state is the only non-trivalent rare earth ion stable in aqueous solutions. Elemental CeriumIt is therefore strongly acidic and oxidizing, in addition to being moderately toxic.The cerous state closely resembles the other trivalent rare earths. Cerium is found in the minerals allanite, bastnasite, hydroxylbastnasite, monazite, rhabdophane, synchysite and zircon. Cerium was discovered by Martin Heinrich Klaproth, Jöns Jakob Berzelius, and Wilhelm Hisinger in 1803 and first isolated by Carl Gustaf Mosander in 1839. The element was named after the asteroid Ceres, which itself was named after the Roman god of agriculture.

Europium

See more Europium products. Europium (atomic symbol: Eu, atomic number: 63) is a Block F, Group 3, Period 6 element with an atomic radius of 151.964. Europium Bohr ModelThe number of electrons in each of Europium's shells is 2, 8, 18, 25, 8, 2 and its electron configuration is [Xe]4f7 6s2. The europium atom has an atomic radius of 180 pm and a Van der Waals radius of 233 pm. Europium was discovered by Eugène-Anatole Demarçay in 1896, however, he did not isolate it until 1901. Europium was named after the continent of Europe.Elemental Europium Picture Europium is a member of the lanthanide or rare earth series of metals. In its elemental form, it has a silvery-white appearance but it is rarely found without oxide discoloration. Europium is found in many minerals including bastnasite, monazite, xenotime and loparite. It is not found in nature as a free element.

Gadolinium

See more Gadolinium products. Gadolinium (atomic symbol: Gd, atomic number: 64) is a Block F, Group 3, Period 6 element with an atomic radius of 157.25. Gadolinium Bohr ModelThe number of electrons in each of Gadolinium's shells is [2, 8, 18, 25, 9, 2] and its electron configuration is [Xe] 4f7 5d1 6s2. The gadolinium atom has a radius of 180 pm and a Van der Waals radius of 237 pm. Gadolinium was discovered by Jean Charles Galissard de Marignac in 1880 and first isolated by Lecoq de Boisbaudran in 1886. In its elemental form, gadolinium has a silvery-white appearance. Gadolinium is a rare earth or lanthanide element that possesses unique properties advantageous to specialized applications such as semiconductor fabrication and nuclear reactor shielding. Elemental Gadolinium PictureIt is utilized for both its high magnetic moment (7.94μ B) and in phosphors and scintillator crystals. When complexed with EDTA ligands, it is used as an injectable contrast agent for MRIs. The element is named after the Finnish chemist and geologist Johan Gadolin.

Related Forms & Applications