Europium Atoms Research Articles

Preparation and Characterization of EuO/BaO Bilayer Epitaxially Grown on SrTiO3Substrate

We grew epitaxially single phase ferromagnetic EuO film on SrTiO 3 substrate by inserting BaO buffer layer with an orientation of EuO[100]//BaO[100]//SrTiO 3 [110] and EuO(001)//BaO(001)//SrTiO 3 (001). Compared with EuO film on MgO substrate, high quality of the film was obtained, demonstrated by appearance of Kikuchi line in RHEED pattern with less thickness, Laue oscillations around EuO(002) Bragg peak, lower full width of half maximum of rocking curve for EuO(002), and lower coercive field. The growth rate of EuO was between 8.0×10 -2 and 2.6×10 -1 A· s -1 , depending on the growth condition. Saturation magnetic moment 6.84(±0.31)µ B was obtained per europium atom. The oxygen deficiency of EuO film was estimated as less than 0.03% from the temperature dependence of resistivity. The highest resistivity detected was 2.55×10 11 Ω· cm at 83.8 K.

Crystal structure and luminescence of a europium 3-methoxybenzoate complex with 2,2′-bipyridine

The structure of the dimer [Eu( m-MOBA) 3·2,2′-bipy] 2 ( m-MOBA: m-methoxybenzoate, 2,2′-bipy: 2,2′-bipyridine) was determined by single crystal X-ray diffraction. Each europium atom is coordinated with two oxygen atoms of the chelated carboxyl group, four oxygen atoms of the bidentate bridging carboxylate groups and two nitrogen atoms from a 2,2′-bipyridine molecule forming a dimeric structure with coordination number 8. The luminescence behaviour of the Eu 3+ ion in [Eu( m-MOBA) 3·2,2′-bipy] 2 was observed at 77 K. The emission spectra of 5 D 1→ 7 F J (J=1–3) and 5 D 0→ 7 F J (J=0–4) transitions were measured. The complex displays intense luminescence and the Eu 3+ ions in the dimer occur in slightly different chemical environments.

Equiatomic Intermetallic Europium Compounds: Syntheses, Crystal Chemistry, Chemical Bonding, and Physical Properties

The crystal chemistry of ternary equiatomic europium compounds EuTX (T = transition metal; X = element of the III, IV, or V main group) is reviewed. Besides preparation techniques we have especially focused on the structure−property relationships and peculiarities in chemical bonding. A main interest in these compounds is the valence state of the europium atoms. The magnetic susceptibility and electrical conductivity data, 151Eu Mössbauer spectroscopic results and LIII X-ray absorption experiments are discussed in detail.

New odd-parity energy levels of europium atoms in the 43 200-45 000 cm-1 region by laser photoionization spectroscopy

Odd-parity energy levels of europium atoms (Eu I) have been investigated by employing single-colour and two-colour stepwise resonance ionization spectroscopy techniques with a heat-pipe oven for metal vapour containment and a thermionic diode for ion detection. Eighty-two new odd-parity energy levels of Eu I have been found in the energy region 43 200-45 000 cm-1. The J quantum numbers for all these newly discovered energy levels have been uniquely assigned. In addition to this, some of the energy levels previously reported by us and assigned more than one J quantum number have been re-investigated and unique J quantum numbers for these levels have been determined.

Structure of a novel polynuclear europium compound with N-phosphonomethylglycine: heptaaquaperchloratodi-μ4-N-phosphonomethylglycine-dieuropium(III) triperchlorate monohydrate, [Eu2(HO3PCH2NH2CH2CO2)2(H2O)7(ClO4)]·3ClO4·H2O

The solid-state structure of the europium(III) complex with N-phosphonomethylglycine (PMG) has been obtained from aqueous solution, at pH ca. 1.6, where a 1:1 M:L molar ratio has been kept. The crystal structure of the [Eu2(HO3PCH2NH2CH2CO2)2(H2O)7(ClO4)]·3ClO4·H2O compound has been determined by single-crystal X-ray diffraction. In the structure of the title compound a two-dimensional polymer is formed, with an unexpected architecture. The oxygen atom of one of four perchlorate groups is engaged in the coordination besides that of the PMG groups. The glyphosate molecules are present as zwitterions. The polymeric chains are composed of two types of dimeric subunits. The first one is created by simple and chelating carboxyl bridges, and the second by phosphonate groups; in the latter type the dimeric unit coordination of metal ions is completed by two oxygen atoms of two perchlorate groups. In the first subunit four, and in the second subunit three water molecules are coordinated by each europium atom. The eighth water molecule and three of four perchlorate groups are outside the metal coordination. Therefore, two non-equivalent metal sites, eight- and nine-fold coordinated, exist in the structure. The structure is stabilized by an extended network of hydrogen bonds. The conformations of the two PMG molecules are quite different.

Preparation and Magnetic Properties of EuO Thin Films Epitaxially Grown on MgO and SrTiO 3 Substrates

Ferromagnetic EuO films were epitaxially grown on MgO and SrTiO 3 substrates aligned with EuO[100]//MgO[100], EuO(001)//MgO(001) and EuO[100]//SrTiO 3 [110], EuO(001)//SrTiO 3 (001). The single phase EuO film was obtained on MgO substrate. The higher order oxides, Eu 2 O 3 , was always present in the films on SrTiO 3 substrate due to the reaction of europium metal and grown EuO with oxygen in SrTiO 3 . The optimized flux ratio of oxygen to europium, J OXY / J Eu , was 0.39, for J Eu =2.83× 10 13 cm -2 · s -1 . The representative growth rate was 9.0×10 -2 Å/s on MgO. Magnetic moment per europium atom was 6.9± 0.3 µ B . The Curie temperature was 69 K for films on MgO. The T C higher than 69 K was observed for films on SrTiO 3 thicker than 50 Å. The thickness of 400 Å was enough for the coercive field to be as low as 50 Oe.

Structure and Properties of the Stannide Eu2Au2Sn5, and its Relationship with the Family of BaAl4-Related Structures

The stannide Eu2Au2Sn5 was prepared by high-frequency melting of the elements in a sealed tantalum tube. The structure of Eu2Au2Sn5 was refined from single crystal X-ray data: P21/m, a = 928.6(2), b = 465.8(2), c = 1042.9(3) pm, ß = 92.28(2)°, wR2 = 0.0653, 1220 F2 values and 56 variables. The structure of Eu2Au2Sn5 is of a new type, it can be considered as an ordered defect variant of the BaAl4 type. Due to the ordered defects, the coordination number (CN) of the two crystallographically different europium sites is reduced from CN 16 to CN 14. The gold and tin atoms in Eu2Au2Sn5 form a complex three-dimensional [Au2Sn5] polyanion in which the europium atoms are embedded. Within the polyanion short Au-Sn and Sn-Sn distances are indicative of strongly bonding Au-Sn and Sn-Sn interactions. A detailed group-subgroup scheme for various ordered and defect variants of the BaAl4 family is presented. Eu2Au2Sn5 shows Curie-Weiss behavior above 50 K with an experimental magnetic moment of 7.90(5) μB/Eu, indicating divalent europium. Antiferromagnetic ordering is detected at 5.8(5) K at low fields and a metamagnetic transition occurs at a critical field of 1.4(2) T. Eu2Au2Sn5 is a metal with a specific resistivity of 150±20 μfΩcm at room temperature. The results of 151Eu and 119Sn Mössbauer spectroscopic experiments are compatible with divalent europium and show complex hyperfine field splitting with a transferred magnetic hyperfine field at the tin nuclei at low temperature.

Syntheses, Crystal Structures, and Properties of EuRhIn, EuIr2, and EuIrSn2

The title compounds were prepared from the elements by reactions in sealed tantalum tubes in a high-frequency furnace. Their structures were refined from single crystal X-ray diffractometer data: Pnma, a=744.4(1) pm, b=434.15(9) pm, c=845.5(1) pm, wR2=0.0433, 658 F2 values, 20 variables for EuRhIn, Fd3m, a=756.5(1) pm, wR2=0.0349, 94 F2 values, 5 variables for EuIr2, and Cmcm, a=434.78(3) pm, b=1124.0(1) pm, c=751.20(5) pm, wR2=0.0561, 565 F2 values, 16 variables for EuIrSn2. EuRhIn crystallizes with a TiNiSi type structure that consists of strongly puckered Rh3In3 hexagons. The europium atoms fill the channels within the three-dimensional [RhIn] polyanion. EuRhIn orders ferromagnetically at 22.0(5) K with a saturation magnetic moment of 6.7(1) μB/Eu at 4 K and 5.5 T. The divalent character of the europium atoms in EuRhIn was determined from temperature dependent susceptibility (7.9 μB/Eu in the high-temperature part) and 151Eu Mössbauer spectroscopic experiments. The latter show an isomer shift of δ=−8.30(2) mm/s at 78 K. At 4.2 K full magnetic hyperfine field splitting subjected to significant quadrupole splitting of ΔEQ=8 mm/s is observed. EuRhIn is a metallic conductor with a room temperature value of 58 μΩcm for the specific resistivity. The structure of the Laves phase EuIr2 is confirmed on the basis of single crystal X-ray data. The iridium atoms form a tetrahedral network with Ir–Ir distances of 268 pm. EuIrSn2 adopts a MgCuAl2 type structure that may be described as an iridium-filled variant of a distorted CaIn2-like sublattice of composition EuSn2. The tin atoms in the distorted and puckered hexagonal network have shorter (303 and 322 pm) and longer (343 pm) tin-tin contacts.

Structure and Properties of Sr2Au3In4 and Eu2Au3In4

Sr2Au3In4 was synthesized by reacting the elements in glassy carbon crucibles under an argon atmosphere in a high-frequency furnace. Eu2Au3In4 was obtained in the same way but starting with EuAuIn as a precursor and admixing indium and gold. Both compounds were investigated by X-ray diffraction on powders and single crystals: anti-Hf2Co4P3 type, P62m, a=1501.6(9) pm, c=457.9(2) pm, wR2=0.0734, 1030 F2 values, 45 variables for Sr2Au2.85In4.15 and a=1489.7(3) pm, c= 454.90(7) pm, wR2=0.1222, 1051 F2 values, 45 variables for Eu2Au3In4. One gold site in the strontium compound shows a mixed occupancy with indium atoms indicating a small homogeneity range according to Sr2Au3−xIn4+x. Striking structural motifs of Sr2Au3In4 and Eu2Au3In4 are gold-centered trigonal prisms formed by the strontium (europium) and indium atoms. All gold atoms have coordination number 9 in the form of tricapped trigonal prisms. The indium atoms in Sr2Au3In4 and Eu2Au3In4 occupy the cobalt positions of the Hf2Co4P3 type and the more electronegative gold atoms take the phosphorus positions, indicating that Sr2Au3In4 and Eu2Au3In4 may be considered as ternary aurides. The gold and indium atoms form three-dimensional [Au3In4]4− polyanions in which the divalent strontium and europium atoms occupy distorted hexagonal tubes. Magnetic susceptibility measurements of Eu2Au3In4 show paramagnetic behavior above 50 K with an experimental magnetic moment of 7.88(5) μB/Eu indicating Eu2+. Antiferromagnetic ordering is detected at 9.5(5) K at low external fields. A metamagnetic transition is observed at 2 K at a critical field of 0.5(2) T. The experimental saturation moment at 2 K and 5.5 T is 5.95(5) μB/Eu. Electrical conductivity investigations exhibit metallic behavior with a room temperature value of 75±10 μΩcm for the specific resistivity. 151Eu Mössbauer spectroscopic measurements show a broadened line with an isomer shift of −10.5(5) mm/s at 78 K in accordance with several sites of divalent europium. Below 10 K magnetic hyperfine field splitting is observed.

Construction of Energy Matrix for Complex Atoms. Part2

The formulae for electrostatic interaction between theconfigurations nlN + 2,nlN + 1n'l',nlNn'l'n''l'',nlNn'l'2,nlN – 1n'l'n'' s2 and the configurationnlN – 1n'l'2n''l''are given.The formulae will be applied to the fine structure analysis of even configurations of the europium atom Eu I.

Utility of 2-Methoxyethanol in the Synthesis of Polyeuropium Complexes: {[Eu(OCH2CH2OMe)2(OC6H3R2-2,6)-][H+]}4 (R = Me, iPr) and [EuAl2(OCH2CH2OMe)3Me5]2

Europium reacts with 2-methoxyethanol at room temperature to form arene-soluble [Eu(OCH{sub 2}CH{sub 2}OMe){sub 2}]n. 1. Reaction of 1 with 2,6-dimethylphenol or 2,6-diisopropylphenol forms the tetrametallic complexes {l_brace}[Eu({mu}{sub 3}-{eta}{sup 2}-OCH{sub 2}CH{sub 2}OMe)({eta}{sup 2}-OCH{sub 2}CH{sub 2}OMe)(OC{sub 6}H{sub 3}R{sub 2}-2,6){sup {minus}}][H{sup +}]{r_brace}{sub 4} (R = Me, 2; R = {sup i}Pr, 3). Magnetic measurements of 1--3 in solution are consistent with the presence of divalent europium. 2 and 3 are isostructural and contain a tetrahedral arrangement of europium atoms. Coordinated to each seven-coordinate metal are one terminal bidentate alkoxide, one bridging bidentate alkoxide, which bridges through its alkoxide oxygen to two other europium atoms, a terminal aryloxide, and two bridging oxygen atoms from other such units. The presence of protons in 2 was probed by reaction with Al{sub 2}Me{sub 6}, which forms hexametallic [Me{sub 3}Al({mu}-{eta}{sup 2}-OCH{sub 2}CH{sub 2}OMe)Eu({mu}-{eta}{sup 2}-OCH{sub 2}-CH{sub 2}OMe){sub 2}AlMe{sub 2}]{sub 2}, 4. Each six-coordinate europium in 4 is surrounded by three bidentate 2-methoxyethoxide ligands, which bridge via their alkoxide oxygen atoms. One ligand bridges to one AlMe{sub 3} unit, and the other two ligands bridge to AlMe{sub 2} units.

Magnetic trapping of atomic chromium

Recently we demonstrated the technique of buffer-gas loading of neutral species by using it to load a magnetic trap with europium atoms @1,2#. The atom density achieved in that experiment ( n;10 12 cm 23 ! is comparable to the highest densities achieved in magneto-optical traps, and the number trapped ( N;10 12 ) is an order of magnitude higher than can currently be obtained with light-force traps @3#. The buffer-gas method promises the extension of magnetic trapping and evaporative cooling to species other than alkali atoms, and should open the way for producing ultracold, dense samples in a variety of atomic and molecular species. Herein, we report the magnetic trapping of atomic chromium via buffer-gas loading. Chromium has many properties of interest. It is a metal dissimilar to europium; trapping it further demonstrates the generality of buffer-gas loading. Chromium’s large magnetic moment of 6 m B ~Bohr magneton! allows for trapping at elevated buffer-gas temperatures, opening up the possibility to trap it with a simple pumped liquid helium cryostat. Study of chromium is also motivated by its applications in atom lithography @4,5#. As it has four naturally occurring isotopes, three bosons and one fermion, trapping could open the door to the study of chromium BoseEinstein condensates or degenerate Fermi gases @6‐9#. The principles of buffer-gas loading and the specifics of our apparatus are outlined in previous papers @1,2#. We give a brief description below. Our magnetic trap is a linear quadrupole field formed by two anti-Helmholtz coils. The trapping region is filled with helium buffer gas. The buffer gas is maintained at cryogenic temperatures by a dilution refrigerator. The species of interest ~atomic chromium in this case! is introduced into the trap, where it diffuses through the helium gas and quickly thermalizes with it via elastic collisions. The atoms in the weak-field-seeking magnetic states are contained by the magnetic fields, but as the atoms are thermally distributed, they evaporate from the trap at a rate determined by h, the ratio of the trap depth to the temperature of the atoms. For a sufficiently large h, this evaporation is slow enough that a large fraction of the atoms may be held for a long enough time that the ~nonmagnetic! helium gas can be ~cryo-!pumped out of the trapping region. This leaves a thermally isolated, trapped sample. Because this technique relies only on elastic collisions with the buffer gas and on the magnetic state of the species, it should be applicable to any magnetic species that can be cleanly introduced into the cryogenic environment. In our experiment, Cr atoms are produced, thermalized, and trapped within a copper cell. There is a fused silica window on the bottom of the cell to permit optical access ~for detection and ablation! and a mirror on the top of the cell to retroreflect the probe beam for absorption spectroscopy of the trapped sample. Resistance thermometry is used to determine the cell temperature. Additional resistors attached to the cell are used as heaters. The cell is filled with either 3 He or 4 He buffer gas. A sufficient amount of 3 He ( 4 He) is present so that at temperatures above 0.3 K ~0.9 K! the density is approximately 10 17 cm 23 . Below these temperatures, the density is determined by the helium vapor pressure. The Cr atoms are brought into the gas phase by single pulse laser ablation of a solid sample of isotopically pure 52 Cr. The solid 52 Cr is positioned at the edge of the trapping region inside the cell. A doubled yttrium-aluminum-garnet laser with typical ablation pulse energy of 25 mJ at 532 nm is used for ablation. The atoms are detected by laser absorption spectroscopy on the a 7 S3$z 7 P3 transition at 23 386 cm 21

Metal valence states inEu0.7NbO3,EuNbO3,andEu2Nb5O9by TB-LMTO-ASA band-structure calculations and resonant photoemission spectroscopy

The electronic structures of ${\mathrm{Eu}}_{2}{\mathrm{Nb}}_{5}{\mathrm{O}}_{9},$ ${\mathrm{EuNbO}}_{3},$ and ${\mathrm{Eu}}_{0.7}{\mathrm{NbO}}_{3}$ have been investigated by photoemission and total-yield spectroscopy with synchrotron radiation, and in the case of ${\mathrm{Eu}}_{2}{\mathrm{Nb}}_{5}{\mathrm{O}}_{9}$ by tight-binding linear muffin-tin orbital (LMTO) band-structure calculations. A central question for reduced europium niobates is that of the valence of Eu and Nb. Both europium and niobium atoms can appear in different valence states so that various electronic configurations in the title compounds are possible. For this reason, the valence band was studied by the resonant Eu $4\stackrel{\ensuremath{\rightarrow}}{d}4f$ technique to determine the Eu valence. The final-state ${4f}^{6}$ multiplet of divalent Eu is dominant in all spectra. Since there are no $4f$ density of states at the Fermi level, valence fluctuations are not expected. The niobium valence states were investigated by core-level spectroscopy. We found only one ${3d}_{5/2}{3d}_{3/2}$ doublet for the Nb $3d$ core level in ${\mathrm{EuNbO}}_{3}$ and ${\mathrm{Eu}}_{0.7}{\mathrm{NbO}}_{3},$ while in ${\mathrm{Eu}}_{2}{\mathrm{Nb}}_{5}{\mathrm{O}}_{9},$ two $3d$ doublets have been observed, corresponding to two chemically distinct niobium atoms in this compound. The ${3d}_{5/2}$ peak in ${\mathrm{EuNbO}}_{3}$ is assigned to the $+4$ nominal valence state at a binding energy of 209.7 eV. The doublet of ${\mathrm{Eu}}_{0.7}{\mathrm{NbO}}_{3}$ is observed at 0.5 eV higher binding energy (at 210.2 eV), which then corresponds to a nominal ${\mathrm{Nb}}^{+4+\mathrm{\ensuremath{\delta}}}$ chemical state. In ${\mathrm{Eu}}_{2}{\mathrm{Nb}}_{5}{\mathrm{O}}_{9},$ the valence of Nb in the ${\mathrm{NbO}}_{6}$ octahedra is less than $+5$ and in the ${\mathrm{Nb}}_{6}{\mathrm{O}}_{12}$ clusters is close to $+2$ as expected. This is in accordance with the LMTO band-structure calculations.

Helium Droplets: A Nanoscale Cryostat for High Resolution Spectroscopy and Studies of Quantized Vorticity

In this paper we discuss helium droplets as a nanoscale cryostat for a variety of fundamental experiments in condensed matter physics. Specifically, we describe our recent work on the spectroscopy of silver atoms, europium atoms and C60in helium droplets and compare the helium droplet, as a matrix for low temperature studies of complex systems, with traditional matrix and gas phase techniques. Further, we discuss our recent work on the production of ultra-cold metal clusters of silver, indium and europium embedded in helium droplets at a temperature (T=0.37K) two orders of magnitude lower than previously achieved in beams of free metal clusters. This work opens the door to high resolution spectroscopic studies of metal clusters and, possibly, high resolution studies of the size dependence of their superconducting properties. We further speculate on a series of experiments where we plan to use standard spectroscopic methods, developed in recent years, to exploit the helium droplet for studies of the existence, stability and dynamics of quantized vortices. Helium droplets may be the ideal system for such studies due to the complete absence of pinning sites that plague many similar experiments performed in bulk helium.

Europium: electron excitation and decay of 4d core holes

Electron emission and electron energy loss spectra of atomic europium excited by electron impact with primary energies (140 - 400 eV) in the region of the 4d giant resonance are presented. The observed emission peaks are identified and the strong energy dependence of their relative intensities near the 4d giant resonance is investigated. The emission spectra show seven intense structures in the energy range 50 - 150 eV which arise from different decay channels after 4d subshell excitation. Auger and direct recombination peaks can be identified by comparing our electron-excited spectra with photon-excited spectra. For primary energies above 300 eV the emission spectra are very similar to spectra excited with high-energy electrons . Near the 4d ionization threshold the relative intensities of the peaks change drastically with decreasing primary energy. Within the region = 180 - 140 eV the Auger peaks decrease and direct recombination channels become dominant. Under these conditions the giant resonance in the excitation step is no longer visible. These near-threshold spectra give insight into the decay mechanism of the 4d giant resonance of Eu in electron scattering. The dominance of direct recombination channels indicates the enhancement of discrete 4d - 4f excitations with impact energies near the resonance.

Lanthanide Phosphido Complexes: A Comparison of the Divalent Homoleptic Species Ln[(μ-PtBu2)2Li(thf)]2 (Ln = Yb, Eu, Sm) Including the Structural Characterization and a Europium-151 Mössbauer Spectrum of Eu[(μ-PtBu2)2Li(thf)]21

A comparison of the three isostructural homoleptic lanthanide phosphide species Ln[(&mgr;-P(t)Bu(2))(2)Li(thf)](2) [Ln = Yb (1), Eu (2), Sm (3)] is reported. Eu(OSO(2)CF(3))(3) reacts with 5 equiv of LiP(t)Bu(2) in tetrahydrofuran to give the europium complex Eu[(&mgr;-P(t)Bu(2))(2)Li(thf)](2) (2) in 50% yield plus 0.5 equiv of (t)Bu(2)P-P(t)Bu(2). 2 crystallizes in space group P2(1)/c. Crystal data for 2 at 248 K: a = 21.740(3) Å, b = 12.345(1) Å, c = 20.633(2) Å, beta = 109.13(1) degrees; V = 5231.5(10) Å(3); Z = 4; D(calcd) = 1.131 g cm(-)(3); R(F)() = 3.29%. The molecular structure shows the four-coordinate europium atom in a distorted tetrahedral environment. A main feature of the crystal structure of 2 is the shortest Eu-P distance [3.034(1) Å] of divalent europium reported so far. A (151)Eu Mössbauer spectrum at 4.2 K is reported exhibiting an isomer shift of -11.7 mm/s.

Buffer-Gas Loading and Magnetic Trapping of Atomic Europium

Atomic europium has been magnetically trapped using buffer-gas loading. Laser ablated $\mathrm{Eu}(^{8}S_{7/2})$ atoms are thermalized to 800 mK in a ${}^{4}\mathrm{He}$ buffer gas (to 250 mK in a ${}^{3}\mathrm{He}$ buffer gas). Anti-Helmholtz superconducting coils produce a quadrupole magnetic field to trap the ${M}_{J}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}7/2$ state of Eu. Detection is via absorption spectroscopy at 462.7 nm. Up to $1\ifmmode\times\else\texttimes\fi{}{10}^{12}\mathrm{Eu}$ atoms are loaded at a central density of $5\ifmmode\times\else\texttimes\fi{}{10}^{12}\phantom{\rule{0ex}{0ex}}{\mathrm{cm}}^{\ensuremath{-}3}$. Atoms can be held for longer than 100 s.

The UV-absorption of europium atoms embedded in helium nanodroplets

We have measured the UV-absorption spectrum (4f→5d transitions) of single europium atoms embedded in helium droplets using a beam depletion technique. The electronic levels involved in the transition lie spatially within the closed 6s2 shell leading to significant shielding from the surrounding helium environment. We observe the narrowest absorption lines ever reported in liquid helium and compare our data and experimental method, with experiments carried out in bulk liquid helium.

Crystal Structure and Spectra of Complex [Eu( o-ABA) 3bipy]bipy

[Eu( o-ABA) 3bipy]bipy (where o-ABA = o-aminobenzoate and bipy = 2,2′-bipyridine) was synthesized and characterized by X-ray diffraction, IR and Raman spectra. In the crystal the compound exists as a dimer, each europium atom is eight-coordinated and has one bipyridine molecule, one bidentate carboxylate group and four oxygen atoms from bridging caboxylates. Luminescence data show that the complex contains one Eu II ion in a site with low symmetry. Copyright © 1996 Elsevier Science Ltd

The Stannides EuPdSn and EuPtSn

Abstract EuPdSn and EuPtSn were prepared from the elements in tantalum tubes at 1070 K and investigated by X-ray diffraction on both powder as well as single crystals. They crystallize with the TiNiSi type structure of space group Pnma and with Z = 4 formula units per cell. Both structures were refined from single-crystal diffractometer data: a = 751.24(9), b = 469.15(6), c = 804.31(9) pm, V = 0.2835(1) nm3 for EuPdSn, and a = 753.38(7), b = 467.72(4), c = 793.08(7) pm, V = 0.2795(1) nnr for EuPtSn. The structures consist of three-dimensional [PdSn] and [PtSn] polyanionic networks in which the europium atoms are embedded. The crystal chemistry of these stannides is briefly discussed