Crystal structure of monoclinic samarium and cubic europium sesquioxides and bound coherent neutron scattering lengths of the isotopes <sup>154</sup>Sm and <sup>153</sup>Eu

Kohlmann, Holger; Hein, Christina; Kautenburger, Ralf; Hansen, Thomas C.; Ritter, C.; Doyle, Stephen

doi:10.1515/zkri-2016-1984

Cited by 18 publications

(17 citation statements)

References 31 publications

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“…These values are in good agreement with known compounds such as TaON, Ta 3 N 5 , Ta 2 O 5 and EuTa(N,O) 3 . Eu II has an ionic radius of 1.35 Å and is coordinated by 12 anions forming a distorted cuboctahedron, similar to the nitride oxide perovskite EuTa(N,O) 3 , whereas the smaller Eu III has a radius of 1.01 Å and is coordinated by seven anions resulting in a single‐capped trigonal prism, which is similar to the coordination of Eu III in Eu 2 O 3 , . The distances between Eu II and the associated 12 N/O ligands are between 2.632(3) – 3.024(3) Å.…”

Section: Resultssupporting

confidence: 85%

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Ammonothermal Synthesis of the Mixed‐Valence Nitrogen‐Rich Europium Tantalum Ruddlesden‐Popper Phase Eu^IIEu^III₂Ta₂N₄O₃

et al. 2019

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The mixed‐valence europium tantalum nitride oxide EuIIEuIII2Ta2N4O3 was synthesized with the ammonothermal approach in high‐pressure custom‐built autoclaves. The reaction was performed at 1070 K and a maximum pressure of 170 MPa in an ammonobasic environment with NaN3 and NaOH as mineralizers. EuIIEuIII2Ta2N4O3 was obtained as a black microcrystalline powder. Single‐crystal synchrotron diffraction data revealed a Ruddlesden‐Popper phase crystallizing in space group P42/mnm (no. 136) with a = 5.7278(1), c = 19.8149(5) Å and Z = 4. The crystallographic results from single‐crystal diffraction data have been confirmed by powder diffraction and TEM measurements. Anion positions were assigned to O and N based on bond‐valence (BVS), lattice energy (MAPLE) and charge distribution calculations (CHARDI). EuII and EuIII are crystallographically ordered. The band gap was estimated from UV/Vis measurements employing the Kubelka–Munk function to be 0.6 eV, which supports the black color and the mixed valence of europium.

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Section: Resultssupporting

confidence: 85%

“…MAPLE values were calculated for each ion type and for the entire structure. The sum formula was formally separated into the binary compounds Ta 3 N 5 , TaNO, EuO, Eu 2 O 3 . Compared to the sum of total MAPLE values, the deviation of total lattice energies of Eu II Eu III 2 Ta 2 N 4 O 3 is 0.6 % (Table ).…”

Section: Resultsmentioning

confidence: 99%

Ammonothermal Synthesis of the Mixed‐Valence Nitrogen‐Rich Europium Tantalum Ruddlesden‐Popper Phase Eu^IIEu^III₂Ta₂N₄O₃

et al. 2019

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“…Calcium and samarium hydride were obtained from the treatment of 2 g calcium shots (Alfa Aesar, 99.5%) and 3 g metallic samarium dendrites (Smart Elements, 99.99%) in a 15 MPa hydrogen atmosphere (Air Liquide, 99.9%) in a home-built Inconel autoclave (Böhler L718V) with copper gasket. The samples were initially annealed for 2 h at 650 K and subsequently for 48 h at 520 K. Samarium oxide used for the reaction with samarium hydride and fluoride was pretreated thermally at 1425 K for 6 h in an open corundum crucible in air and transferred while hot into the glovebox . Samarium fluoride (Alfa Aesar, 99.99%) was dried in an open corundum crucible under dynamic vacuum ( p < 10 Pa) for 1 h at 1375 K and subsequently transferred into the glovebox.…”

Section: Methodsmentioning

confidence: 99%

“…The samples were initially annealed for 2 h at 650 K and subsequently for 48 h at 520 K. Samarium oxide used for the reaction with samarium hydride and fluoride was pretreated thermally at 1425 K for 6 h in an open corundum crucible in air and transferred while hot into the glovebox. 33 Samarium fluoride (Alfa Aesar, 99.99%) was dried in an open corundum crucible under dynamic vacuum (p < 10 Pa) for 1 h at 1375 K and subsequently transferred into the glovebox.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

From SmOF to SmH_0.78OF_0.22: H/F Substitution in Oxide Fluorides as a Synthesis Route to Heteroanionic Compounds

2021

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Mixed anionic hydrides of the rare earths are a fascinating class of compounds as potential functional materials, especially in luminescence, as photochromic thin films and for ion conduction. For exploratory studies, the effectiveness of various synthesis methods must be investigated, which is done here for metathesis reactions. The reaction of Sm2O3 with PTFE yields SmOF (P21/c, a = 5.60133(19) Å, b = 5.65567(19) Å, c = 5.6282(2) Å, β = 90.169(5)°, V = 178.295(11) Å3, and Z = 4) in a new, probably metastable, polymorph of the baddeleyite-type structure. Metathesis reactions of SmOF with LiH, NaH, or CaH2 led to a samarium hydride oxide fluoride, SmH x OF1–x ; i.e., incomplete H/F exchange occurs. X-ray diffraction and neutron diffraction on a compound with x = 0.78 obtained via NaH reveal hydride, oxide, and fluoride ions to be partially ordered. SmH0.78OF0.22 (Ia3̅, a = 10.947(2) Å, V = 1311.7(4) Å3, Z = 32) crystallizes in an anti-Li3AlN2-type structure with distorted cubic anion coordination for samarium atoms (site symmetry 3̅ and 2) and distorted tetrahedral arrangement of samarium atoms around the anions (site symmetry 1 and 3). It is a fully structurally characterized hydride oxide fluoride and shows a rare crystal chemical featurethe occupation of a crystallographic site by three different anions (0.188 H + 0.667 O + 0.145 F). Interatomic distances between samarium and hydrogen and samarium and the mixed hydrogen/oxygen/fluorine site range from 2.45 to 2.48 Å and 2.29 to 2.42 Å, respectively, and are similar to those in samarium hydride, samarium oxide, and samarium fluoride. Fluoride extraction by reaction with alkali and alkaline earth hydrides has thus proven to be a useful synthesis route to hydride oxides and also hydride oxide halogenides, which might be further exploited in exploratory research on heteroanionic metal hydrides.

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“…Rietveld refinement has often been used as a method of scattering length determination (Boucherle & Schweizer, 1975;Koester et al, 1991;Rodriguez et al, 2007;Kennedy & Avdeev, 2011;Kohlmann et al, 2016) and the site occupancy can be refined as a proxy for scattering length in standard Rietveld programs. We performed a Rietveld refinement of the ND data collected on GEM for Sr 2 IrO 4 to evaluate the application of this method to the measurement of the scattering length, b iso , for iso Ir.…”

Section: Rietveld Refinement For Sr 2 Iromentioning

confidence: 99%

Neutron scattering length determination by means of total scattering

2018

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A new method for the measurement of bound coherent neutron scattering lengths is reported. It is shown that a relative measurement of the neutron scattering length, , of an element can be made by analysis of the neutron correlation function of a suitable oxide crystal powder. For this analysis, it is essential to take into account the average density contribution to the correlation function, as well as the contributions arising from distances between atoms in the crystal. The method is demonstrated and verified by analysis of the neutron correlation function for the corundum form of Al2O3, yielding a value = 3.44 (1) fm for Al, in good agreement with the literature. The method is then applied to the isotopes of iridium, for which the values of the scattering lengths were unknown, and which are difficult to investigate by other methods owing to the large cross sections for the absorption of neutrons. The neutron correlation function of a sample of Sr2IrO4 enriched in 193Ir is used to determine values = 9.71 (18) fm and = 12.1 (9) fm for 193Ir and 191Ir, respectively, and these are consistent with the tabulated scattering length and cross sections of natural Ir. These values are of potential application for obtaining improved neutron diffraction results on iridates by the use of samples enriched in 193Ir, so that the severe absorption problems associated with 191Ir are avoided. Rietveld refinement of the neutron diffraction pattern of isotopically enriched Sr2IrO4 is used to yield a similar result for Ir. However, in practice the Rietveld result is shown to be less reliable because of correlation between the parameters of the fit.

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Crystal structure of monoclinic samarium and cubic europium sesquioxides and bound coherent neutron scattering lengths of the isotopes ¹⁵⁴Sm and ¹⁵³Eu

Abstract: The crystal structures of monoclinic samarium and cubic europium sesquioxide, Sm

Cited by 18 publications

References 31 publications

Ammonothermal Synthesis of the Mixed‐Valence Nitrogen‐Rich Europium Tantalum Ruddlesden‐Popper Phase Eu^IIEu^III₂Ta₂N₄O₃

Ammonothermal Synthesis of the Mixed‐Valence Nitrogen‐Rich Europium Tantalum Ruddlesden‐Popper Phase Eu^IIEu^III₂Ta₂N₄O₃

From SmOF to SmH_0.78OF_0.22: H/F Substitution in Oxide Fluorides as a Synthesis Route to Heteroanionic Compounds

Neutron scattering length determination by means of total scattering

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Crystal structure of monoclinic samarium and cubic europium sesquioxides and bound coherent neutron scattering lengths of the isotopes 154Sm and 153Eu

Abstract: The crystal structures of monoclinic samarium and cubic europium sesquioxide, Sm

Cited by 18 publications

References 31 publications

Ammonothermal Synthesis of the Mixed‐Valence Nitrogen‐Rich Europium Tantalum Ruddlesden‐Popper Phase EuIIEuIII2Ta2N4O3

Ammonothermal Synthesis of the Mixed‐Valence Nitrogen‐Rich Europium Tantalum Ruddlesden‐Popper Phase EuIIEuIII2Ta2N4O3

From SmOF to SmH0.78OF0.22: H/F Substitution in Oxide Fluorides as a Synthesis Route to Heteroanionic Compounds

Neutron scattering length determination by means of total scattering

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About

Crystal structure of monoclinic samarium and cubic europium sesquioxides and bound coherent neutron scattering lengths of the isotopes ¹⁵⁴Sm and ¹⁵³Eu

Ammonothermal Synthesis of the Mixed‐Valence Nitrogen‐Rich Europium Tantalum Ruddlesden‐Popper Phase Eu^IIEu^III₂Ta₂N₄O₃

Ammonothermal Synthesis of the Mixed‐Valence Nitrogen‐Rich Europium Tantalum Ruddlesden‐Popper Phase Eu^IIEu^III₂Ta₂N₄O₃

From SmOF to SmH_0.78OF_0.22: H/F Substitution in Oxide Fluorides as a Synthesis Route to Heteroanionic Compounds