Ternary plumbides ATPb2 (A = Ca, Sr, Ba, Eu; T = Rh, Pd, Pt) with distorted, lonsdaleite-related substructures of tetrahedrally connected lead atoms

2020 ◽  
Vol 75 (11) ◽  
pp. 903-911
Author(s):  
Steffen Klenner ◽  
Judith Bönnighausen ◽  
Rainer Pöttgen
Keyword(s):  
Mössbauer Spectra ◽  
Magnetic Hyperfine Field ◽  
Structural Motif ◽  
Temperature Dependent ◽  
Moisture Sensitivity ◽  
X Ray ◽  
Mossbauer Spectra ◽  
Divalent Europium ◽  
Direct Reactions ◽  
Moisture Sensitive

AbstractThe plumbides CaTPb2 (T = Rh, Pd), EuTPb2 (T = Rh, Pd, Pt), SrTPb2 (T = Rh, Pd, Pt) and BaTPb2 (T = Pd, Pt) were obtained by direct reactions of the elements in sealed tantalum tubes in an induction furnace. The moisture sensitive polycrystalline samples were characterized by X-ray powder diffraction. They crystallize with the orthorhombic MgCuAl2-type structure, space group Cmcm. The structures of CaRhPb2 (a = 433.78(3), b = 1102.06(8), c = 798.43(6) pm, wR = 0.0285, 432 F2 values and 16 variables) and EuPdPb2 (a = 457.24(5), b = 1158.27(13), c = 775.73(8), wR = 0.0464, 464 F2 values and 16 variables) were refined from single crystal X-ray diffractometer data. The characteristic structural motif is the distorted tetrahedral substructure built up by the lead atoms with Pb–Pb distances of 326–327 pm in CaRhPb2 and of 315–345 pm in EuPdPb2. With increasing size of the alkaline earth (Eu) cation, the lead substructure becomes more anisotropic with a shift of the [TPb2] polyanions from three- to two-dimensional, leading to significantly increased moisture sensitivity. Temperature dependent magnetic susceptibility studies reveal Pauli paramagnetism for SrRhPb2, SrPtPb2, BaPdPb2 and BaPtPb2. EuRhPb2 and EuPdPb2 are Curie–Weiss paramagnets with stable divalent europium as is also evident from 151Eu Mössbauer spectra. EuRhPb2 is a ferromagnet with TC = 17.7(2) K, while EuPdPb2 orders antiferromagnetically at TN = 15.9 K. This is in agreement with the full magnetic hyperfine field splitting of the 151Eu Mössbauer spectra at T = 6 K.

scholarly journals 151Eu Mössbauer Spectroscopic Characterization of EuRu4B4 and the New Boride EuRuB4

2010 ◽  
Vol 65 (1) ◽  
pp. 90-94 ◽  
Author(s):  
Thomas Harmening ◽  
Rainer Pöttgen
Keyword(s):  
Boron Atom ◽  
Mössbauer Spectra ◽  
Induction Furnace ◽  
Spectroscopic Characterization ◽  
Two Dimensional ◽  
Temperature Dependent ◽  
X Ray ◽  
Trivalent Europium ◽  
Mossbauer Spectra

Samples of EuRu4B4 and of the new boride EuRuB4 were prepared from europium, RuB, and RuB4 precursor alloys, respectively, in sealed tantalum tubes in an induction furnace. EuRu4B4 crystallizes with the LuRu4B4 structure, a = 748.1(1), c = 1502.3(4) pm. The structure of EuRuB4 was refined on the basis of X-ray diffractometer data: Pbam, a = 599.7(1), b = 1160.7(3), c = 358.06(7) pm, wR2 = 0.0691, 474 F2 values, and 38 variables. The four crystallographically independent boron sites build up layers which consist of almost regular pentagons and heptagons which sandwich the ruthenium and europium atoms, respectively. Within the two-dimensional [B4] networks each boron atom has a slightly distorted trigonal-planar boron coordination with B-B distances in the range 172 - 186 pm. Temperature-dependent 151Eu Mössbauer spectra show stable trivalent europium for EuRu4B4 and EuRuB4

Antiferromagnetic ordering in the plumbide EuPdPb

2017 ◽  
Vol 72 (12) ◽  
pp. 989-994
Author(s):  
Lukas Heletta ◽  
Steffen Klenner ◽  
Theresa Block ◽  
Rainer Pöttgen
Keyword(s):  
Magnetic Susceptibility ◽  
Magnetic Hyperfine Field ◽  
Metamagnetic Transition ◽  
Muffle Furnace ◽  
Temperature Dependent ◽  
X Ray ◽  
Antiferromagnetic Ordering ◽  
Divalent Europium ◽  
Polycrystalline Form ◽  
Experimental Magnetic Moment

AbstractThe plumbide EuPdPb was synthesized in polycrystalline form by reaction of the elements in a sealed niobium ampoule in a muffle furnace. The structure was refined from single-crystal X-ray diffractometer data: TiNiSi type, Pnma, a=752.4(2), b=476.0(2), c=826.8(2) pm, wR2=0.0485, 704 F2 values and 20 variables. The europium atoms are coordinated by two tilted and puckered Pd3Pb3 hexagons (280–289 pm Pd–Pb) with pronounced Eu–Pd bonding (312–339 pm). Temperature-dependent magnetic susceptibility measurements show Curie-Weiss behaviour and an experimental magnetic moment of 7.35(1) μB per Eu atom. EuPdPb orders antiferromagnetically at TN=13.8(5) K and shows a metamagnetic transition at a critical field of 15 kOe. 151Eu Mössbauer spectra confirm divalent europium (δ=–10.04(1) mm s−1) and show full magnetic hyperfine field splitting (Bhf=21.1(1) T) at 6 K.

The Stannides EuPd2Sn2, EuPt2Sn2, EuAu2Sn2, and Eu5.4Sn5.6 – Structure and Magnetic Properties

2014 ◽  
Vol 69 (7) ◽  
pp. 775-785 ◽  
Author(s):  
Christian Schwickert ◽  
Florian Winter ◽  
Rainer Pöttgen
Keyword(s):  
Magnetic Hyperfine Field ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
Space Group ◽  
X Ray ◽  
Antiferromagnetic Ordering ◽  
Divalent Europium ◽  
Sample Chamber ◽  
Tin Coordination

The europium stannides EuT2Sn2 (T = Pd, Pt, Au) and Eu3Ag5.4Sn5.6 were synthesized by highfrequency melting of the elements in sealed niobium ampoules in a water-cooled sample chamber. All samples were characterized by powder X-ray diffraction. The EuT2Sn2 (T = Pd, Pt, Au) stannides crystallize with the CaBe2Ge2-type structure, space group P4/nmm. The structure of EuPd2Sn2 was refined from single-crystal X-ray diffractometer data: a = 462.44(8), c = 1045.8(3) pm, wR = 0.0402, 237 F2 values and 15 refined variables. The palladium and tin atoms build up a threedimensional [Pd2Sn2] polyanionic network, exclusively with Pd-Sn interactions (261 - 269 pm). The Pd1 and Pd2 atoms have square-pyramidal and tetrahedral tin coordination, respectively. The europium atoms fill large voids within the network. They are coordinated to eight palladium and eight tin atoms. Temperature-dependent magnetic susceptibility studies confirm a stable divalent ground state of the europium atoms. The compounds become ordered antiferromagnetically below 6.3 (EuPd2Sn2), 6.1 (EuPt2Sn2) and 7.7 K (EuAu2Sn2). Eu3Ag5.4Sn5.6 adopts a partially ordered variant of the La3Al11 type, space group Immm, a = 471.33(8), b = 1382.5(4), c = 1032.4(2) pm, wR = 0.0449, 692 F2 values, 30 variables. The three-dimensional [Ag5.4Sn5.6] network shows one silver and one tin site besides two sites with substantial Ag/Sn mixing. The two crystallographically independent europium atoms fill larger and smaller cavities within the [Ag5.4Sn5.6] network. Eu3Ag5.4Sn5.6 also shows divalent europium and antiferromagnetic ordering at TN = 6:9 K. A 151Eu Mössbauer spectrum of Eu3Ag5.4Sn5.6 at 5.2 K shows an isomer shift of δ = −10.61 mms−1, typical for Eu(II) compounds, and a magnetic hyperfine field splitting of BHf = 5.9 T. 119Sn Mössbauer spectra of the four stannides show isomer shifts in the range of δ = 1.78 - 2.20 mms−1, usually observed for tin in intermetallic compounds.

Microstructure Evolution and Mossbauer Spectroscopy Research of Nanostructured Ni3 Fe Intermetallic

2021 ◽  
Vol 32 ◽  
pp. 1-13
Author(s):  
Amel Kaibi ◽  
Abderrahim Guittoum ◽  
Nassim Souami ◽  
Mohamed Kechouane
Keyword(s):  
Magnetic Field ◽  
Mössbauer Spectroscopy ◽  
Mössbauer Spectra ◽  
Milling Time ◽  
Mossbauer Spectroscopy ◽  
Hyperfine Magnetic Field ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mossbauer Spectra ◽  
Mößbauer Spectroscopy

Nanocrystalline Ni75Fe25 (Ni3Fe) powders were prepared by mechanical alloying process using a vario-planetary high-energy ball mill. The intermetallic Ni3Fe formation and different physical properties were investigated, as a function of milling time, t, (in the range 6 to 96 h range), using X-Ray Diffraction (XRD) and Mössbauer Spectroscopy techniques. X-ray diffraction were performed on the samples to understand the structural characteristics and get information about elements and phases present in the powder after different time of milling. The refinement of XRD spectra revealed the complete formation of fcc Ni (Fe) disordered solid solution after 24 h of milling time, the Fe and Ni elemental distributions are closely correlated. With increasing the milling time, the lattice parameter increases and the grains size decreases. The Mössbauer experiments were performed on the powders in order to follow the formation of Ni3Fe compound as a function of milling time. From the adjustment of Mössbauer spectra, we extracted the hyperfine parameters. The evolution of hyperfine magnetic field shows that the magnetic disordered Ni3Fe phase starts to form from 6 h of milling time and grow in intensity with milling time. For the milling time more than 24 h, only the Ni3Fe disordered phase is present with a mean hyperfine magnetic field of about 29.5 T. The interpretation of the Mossbauer spectra confirmed the results obtained by XRD.

scholarly journals Mössbauer study of Fe phases in terrestrial olivine basalts from southern Egypt

Mineralogia ◽  
2013 ◽  
Vol 44 (1-2) ◽  
pp. 3-12 ◽  
Author(s):  
Kamaleldin M. Hassan ◽  
Julius Dekan
Keyword(s):  
Optical Microscopy ◽  
Crystal Chemistry ◽  
Mössbauer Spectra ◽  
Mossbauer Spectroscopy ◽  
X Ray Diffraction ◽  
Mössbauer Study ◽  
Hyperfine Parameters ◽  
X Ray ◽  
Mossbauer Spectra ◽  
Oxidized Iron

AbstractOlivine basalts from southern Egypt were studied by 57Fe Mössbauer spectroscopy at 297 and 77 K, and by optical microscopy and X-ray diffraction. The 57Fe Mössbauer spectra show three-magnetic sextets, three doublets of ferrous (Fe2+), and a weak ferric (Fe3+) doublet that is attributable to a nanophase oxide (npOx). The magnetic sextets relate to titanomagnetite and the Fe2+ doublets to olivine, pyroxene, and ulvöspinel. Variations in the hyperfine parameters of the various Fe components are attributed to changes in the local crystal chemistry. The intensity of oxidation (Fe3+/ΣFe) in the rocks varies from 20-27% with the oxidized iron largely residing in the titanomagnetite.

X-ray diffraction and Mössbauer spectra of the system Fe2O3-SnO2

1991 ◽  
Vol 10 (4) ◽  
pp. 197-200 ◽  
Author(s):  
S. Musić ◽  
S. Popović ◽  
M. Metikoš-Hukovć ◽  
V. Gvozdić
Keyword(s):  
Mössbauer Spectra ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mossbauer Spectra

The ternary platinides CaGa5Pt3 and EuGa5Pt3

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Judith Bönnighausen ◽  
Stefan Seidel ◽  
Steffen Klenner ◽  
Rainer Pöttgen
Keyword(s):  
Induction Furnace ◽  
Three Dimensional ◽  
Covalent Bonding ◽  
Intermetallic Phases ◽  
Temperature Dependent ◽  
X Ray ◽  
Antiferromagnetic Ordering ◽  
Divalent Europium ◽  
Experimental Magnetic Moment ◽  
Magnetic Hyperfine Splitting

Abstract The ternary platinides CaGa5Pt3 (a = 2082.5(4), b = 406.05(8), c = 739.2(1) pm) and EuGa5Pt3 (a = 2085.5(5), b = 412.75(9), c = 738.7(1) pm) were synthesized from the elements in sealed high-melting metal tubes in an induction furnace. CaGa5Pt3 and EuGa5Pt3 are isotypic with CeAl5Pt3 and isopointal with the YNi5Si3 type intermetallic phases (space group Pnma, oP36 and Wyckoff sequence c 9). The structure of EuGa5Pt3 was refined from single crystal X-ray diffractometer data: wR2 = 0.0443, 1063 F 2 values and 56 variables. The gallium and platinum atoms build up a three-dimensional [Ga5Pt3]2− polyanionic network in which the europium atoms fill slightly distorted hexagonal prismatic voids. The Ga–Pt distances within the network range from 249 to 271 pm, emphasizing the covalent bonding character. Temperature dependent magnetic susceptibility measurements indicate diamagnetism for CaGa5Pt3 and isotypic BaGa5Pt3. EuGa5Pt3 behaves like a Curie–Weiss paramagnet above 50 K with an experimental magnetic moment of 8.17(1) µB/Eu atom, indicating divalent europium. Antiferromagnetic ordering sets in at T N = 8.5(1) K. The divalent ground state of europium is confirmed by 151Eu Mössbauer spectroscopy. EuGa5Pt3 shows a single signal at 78 K with an isomer shift of −9.89(4) mm s−1. Full magnetic hyperfine splitting with a hyperfine field of 25.0(2) T is observed at 6 K in the magnetically ordered regime.

57Fe-Mössbauer Spectra and X-Ray Structures of Dipolar Ferrocenylhexasilanes

2008 ◽  
pp. 462-466
Author(s):  
Harald Stger ◽  
Hermann Rautz ◽  
Guido Kickelbick ◽  
Claus Pietzsch
Keyword(s):  
Mössbauer Spectra ◽  
X Ray ◽  
57Fe Mössbauer ◽  
Mossbauer Spectra

Preparation and characterization of iron oxide pillared montmorillonite

Clay Minerals ◽  
1988 ◽  
Vol 23 (4) ◽  
pp. 367-377 ◽  
Author(s):  
D. H. Doff ◽  
N. H. J. Gangas ◽  
J. E. M. Allan ◽  
J. M. D. Coey
Keyword(s):  
Magnetic Properties ◽  
Iron Oxide ◽  
Powder Diffraction ◽  
Mössbauer Spectra ◽  
Pillared Clay ◽  
Cross Linking ◽  
X Ray ◽  
Pillared Montmorillonite ◽  
Mossbauer Spectra

AbstractPillared smectites in which the pillars consist of iron oxide are expected to have interesting and unusual magnetic properties. Several possible routes by which such materials might be made have been investigated, namely intercalation of hydroxy-Fe(III) polycations, mixed hydroxy-Fe(III)/Al polycations, phenanthroline-Fe(II) cations, and trinuclear Fe(III) acetato cations into Na-montmorillonite. Only the last of these yielded a pillared clay (PILC) on calcination. The products have been characterized using X-ray powder diffraction and 57Fe Mössbauer spectroscopy. The precursor Fe-PILC has a d-spacing of 21 Å and expands to 23 Å on solvation with glycol. The calcined Fe-PILC has a d-spacing of 19 Å (gallery height 9·4 Å) and does not expand with glycol, confirming cross-linking of the layers. From Mössbauer spectra at 4·2 K it is estimated that there are of the order of some hundred Fe atoms per pillar.

scholarly journals Local structural properties of (Mn,Fe)Nb2O6 from Mössbauer and X-ray absorption spectroscopy

2005 ◽  
Vol 61 (3) ◽  
pp. 250-257 ◽  
Author(s):  
Serena C. Tarantino ◽  
Paolo Ghigna ◽  
Catherine McCammon ◽  
Roberta Amantea ◽  
Michael A. Carpenter
Keyword(s):  
Mössbauer Spectra ◽  
Manganese Content ◽  
Line Broadening ◽  
Compositional Dependence ◽  
Static Disorder ◽  
X Ray ◽  
Mossbauer Spectra ◽  
Data Line ◽  
Neighbour Effects ◽  
X Ray Absorption

The MnNb2O6–FeNb2O6 solid solution has been investigated by Fe–K- and Mn–K-edge X-ray absorption (XANES and EXAFS), and Mössbauer spectroscopy. The first-shell M—O bond lengths deduced from EXAFS show a fairly small compositional dependence. A degree of static disorder, which increases with increasing manganese content, is clearly seen by the loss of correlation for the next-neighbour (NN) interaction. Hyperfine parameters from Mössbauer spectra are consistent with variations in the average environment, as recorded by X-ray data. Line broadening of the Mössbauer spectra provides evidence for next-neighbour effects and is consistent with there being no significant clustering of Fe or Mn within the samples. There appear to be differences in the way the columbite structure accommodates Fe2+ and Mn2+ ions. In ferrocolumbite all the Fe octahedra are close to being identical, while there are local structural heterogeneities at a longer length scale, presumably in ordering the precise topology of polyhedra immediately adjacent to the octahedron. By contrast, the manganocolumbite seems to have some diversity in the precise coordination at the MnO6 octahedra, but a greater uniformity in how the adjacent polyhedra are configured around them.

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