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

1999 ◽  
Vol 54 (9) ◽  
pp. 1155-1164 ◽  
Author(s):  
Dirk Kußmann ◽  
Rainer Pöttgen ◽  
Ute Ch. Rodewald ◽  
Carsten Rosenhahn ◽  
Bernd D. Mosel ◽  
...  
Keyword(s):  
Hyperfine Field ◽  
Magnetic Hyperfine Field ◽  
Three Dimensional ◽  
X Ray ◽  
Antiferromagnetic Ordering ◽  
Divalent Europium ◽  
The Family ◽  
New Type ◽  
Subgroup Scheme ◽  
Experimental Magnetic Moment

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.

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.

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.

Nickel-deficient Stannides Eu2Ni2–xSn5 – Structure, Magnetic Properties, and Mössbauer Spectroscopic Characterization

2009 ◽  
Vol 64 (10) ◽  
pp. 1107-1114 ◽  
Author(s):  
Thomas Harmening ◽  
Matthias Eul ◽  
Rainer Pöttgen
Keyword(s):  
Solid Solution ◽  
Magnetic Properties ◽  
Powder Diffraction ◽  
Spectroscopic Characterization ◽  
Structure Type ◽  
Induction Melting ◽  
X Ray ◽  
Antiferromagnetic Ordering ◽  
Divalent Europium ◽  
Experimental Magnetic Moment

New nickel-deficient stannides Eu2Ni2−xSn5 were synthesized by induction melting of the elements in sealed tantalum tubes. The solid solution was studied by X-ray powder diffraction and two crystal structures were refined on the basis of X-ray diffractometer data: Cmcm, a = 466.03(4), b = 3843.1(8), c = 462.92(9) pm, wR2 = 0.0469, 692 F2 values, 39 variables for Eu2Ni1.49(1)Sn5 and a = 466.11(9), b = 3820.1(8), c = 462.51(9) pm, wR2 = 0.0358, 695 F2 values, 39 variables for Eu2Ni1.35(1)Sn5. This new structure type can be considered as an intergrowth structure of CaBe2Ge2- and CrB-related slabs. The striking structural motifs are nickel-centered square pyramids which are condensed via common corners and edges. The layers of condensed NiSn5 units are separated by the europium atoms. The Ni1 sites within the CaBe2Ge2 slabs show significant defects which leads to split positions for one tin site. Eu2Ni1.50Sn5 shows Curie-Weiss behavior and an experimental magnetic moment of 7.74(1) μB / Eu atom, indicating stable divalent europium, as is also evident from 151Eu Mössbauer spectra. Antiferromagnetic ordering is detected at 3.5 K.

The stannides Ca1.692Pt2Sn3.308, SrPtSn2 and EuAuSn2

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Steffen Klenner ◽  
Maximilian Kai Reimann ◽  
Stefan Seidel ◽  
Rainer Pöttgen
Keyword(s):  
Magnetic Hyperfine Field ◽  
Three Dimensional ◽  
Magnetic Ordering ◽  
Temperature Dependent ◽  
Crucible Material ◽  
Phase Purity ◽  
X Ray ◽  
Calcium Compound ◽  
Experimental Magnetic Moment ◽  
Tin Coordination

Abstract Polycrystalline samples of the stannides Ca1.692Pt2Sn3.308, SrPtSn2 and EuAuSn2 were synthesized directly from the elements, using sealed tantalum ampoules as crucible material. The reactions were performed in muffle or induction furnaces. The phase purity of the samples was studied by X-ray powder diffraction (Guinier technique). The structures of Ca1.692Pt2Sn3.308 and SrPtSn2 were refined from single-crystal X-ray diffractometer data: NdRh2Sn4 type, Pnma, a = 1887.22(13), b = 441.22(3), c = 742.89(4) pm, wR = 0.0626, 1325 F 2 values, 45 variables for Ca1.692(8) Pt2Sn3.308(8) and CeNiSi2 type, Cmcm, a = 462.59(5), b = 1932.8(2), c = 458.00(5) pm, wR = 0.0549, 481 F 2 values, 18 variables for SrPtSn2. The calcium compound shows a homogeneity range Ca1+x Pt2Sn4−x with substantial Sn4/Ca2 mixing on one of the 4c Wyckoff positions. The [PtSn2] network is characterized by Pt–Sn (269–281 pm) and Sn–Sn (306–336 pm) bonding interactions. SrPtSn2 contains two different tin substructures: (i) Sn1–Sn1 zig-zag chains (282 pm) and (ii) orthorhombically distorted Sn2 squares (326 pm) with stronger and weaker Sn–Sn bonding. Together, the platinum and tin atoms build up a three-dimensional [PtSn2] network in which the platinum atoms have a distorted square-pyramidal tin coordination with Pt–Sn distances ranging from 261–270 pm. EuAuSn2 also crystallizes with the CeNiSi2-type structure with the lattice parameters a = 453.9(1), b = 2018.9(5) and c = 456.8(1) pm. Temperature dependent magnetic susceptibility studies indicate europium(II) with an experimental magnetic moment of 8.28(2) µB per Eu atom. EuAuSn2 is ordered antiferromagnetically at T N  = 14.8(2) K. 151Eu Mössbauer spectra confirm the oxidation state +2 for europium (isomer shift δ = −11.17(2) mm s−1) and the magnetic ordering at low temperature (21.8 T magnetic hyperfine field at 6 K).

Dimorphic EuCu5Cd

2012 ◽  
Vol 67 (10) ◽  
pp. 1107-1114 ◽  
Author(s):  
Frank Tappe ◽  
Christian Schwickert ◽  
Rainer Pöttgen
Keyword(s):  
Magnetic Susceptibility ◽  
Small Degree ◽  
Muffle Furnace ◽  
Temperature Dependent ◽  
X Ray ◽  
Coordination Numbers ◽  
Dsc Measurements ◽  
Divalent Europium ◽  
Experimental Magnetic Moment ◽  
High Coordination

Two modifications of EuCu5Cd were synthesized from the elements in sealed tantalum ampoules.The high-temperature (HT) modification was obtained from an induction-melted sample that was finally annealed at 873 K, while the low-temperature (LT) phase is formed in a muffle furnace by annealing a pre-melted sample at 673 K. DSC measurements gave a transition temperature of 823±2 K. Both structures were refined on the basis of single-crystal X-ray diffractometer data: R3̄m, a = 511:58(7), c = 3059:6(6) pm, wR2 = 0.0289, 316 F2 values, 22 variables for HTEuCu4 :85(1)Cd1:15(1) and Pnma, a = 2545:6(5), b = 511:60(1), c = 1060:3(2) pm, wR2 = 0.0386, 2044 F2 values, 121 variables for LT-EuCu4:92(1)Cd1:08(1). A small degree of Cu/Cd mixing was observed for three sites. Both structures adopt new types. The europium atoms have high coordination numbers of 18, 19 and 20 in LT- and 18 and 20 in HT- EuCu5Cd. These three types of polyhedra are the basic building units also in the closely related structures of CeCu6, CeCu5Au, CeCu4:38In1:62, and CeNi5Sn, a family of stacking variants. Temperature-dependent magnetic susceptibility measurements of a HT- EuCu5Cd sample showed an experimental magnetic moment of 7.56(1) μB per Eu atom in the paramagnetic regime, compatible with divalent europium. HT- EuCu5Cd orders antiferromagnetically at 17.7(5) K.

Ferromagnetic Ordering in the Thallide EuPdTl2

2006 ◽  
Vol 61 (2) ◽  
pp. 159-163 ◽  
Author(s):  
Rainer Kraft ◽  
Sudhindra Rayaprol ◽  
C. Peter Sebastian ◽  
Rainer Pöttgen
Keyword(s):  
Curie Temperature ◽  
Single Crystals ◽  
Magnetic Moment ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
Zintl Phase ◽  
X Ray ◽  
Divalent Europium ◽  
Ferromagnetic Ordering

AbstractThe new thallide EuPdTl2, synthesized from the elements in a sealed tantalum tube in a highfrequency furnace, was investigated by X-ray diffraction on powders and single crystals: MgCuAl2 type, Cmcm, Z = 4, a = 446.6(1), b = 1076.7(2), c = 812.0(2) pm, wR2 = 0.0632, 336 F2 values, 16 variables. The structure can be considered as an orthorhombically distorted, palladium-filled variant of the binary Zintl phase EuTl2. The palladium and thallium atoms build up a three-dimensional [PdTl2] polyanion with significant Pd-Tl (286 - 287 pm) and Tl-Tl (323 - 329 pm) interactions. The europium atoms fill distorted hexagonal channels of the [PdTl2] polyanion. Susceptibility measurements show a magnetic moment of 7.46(5) μB/Eu atom, indicative of divalent europium. EuPdTl2 is a soft ferromagnet with a Curie temperature of TC = 12.5(5) K.

The High-Pressure Modification of CePtSn – Synthesis, Structure, and Magnetic Properties

2005 ◽  
Vol 60 (8) ◽  
pp. 821-830 ◽  
Author(s):  
Jan F. Riecken ◽  
Gunter Heymann ◽  
Theresa Soltner ◽  
Rolf-Dieter Hoffmann ◽  
Hubert Huppertz ◽  
...  
Keyword(s):  
High Pressure ◽  
Magnetic Properties ◽  
High Temperature ◽  
Magnetic Moment ◽  
Three Dimensional ◽  
Magnetic Ordering ◽  
Normal Pressure ◽  
Variable Parameters ◽  
X Ray ◽  
Experimental Magnetic Moment

The high-pressure (HP) modification of CePtSn was prepared under multianvil high-pressure (9.2 GPa) high-temperature (1325 K) conditions from the normal-pressure (NP) modification. Both modifications were investigated by powder and single crystal X-ray data: TiNiSi type, Pnma, a = 746.89(9), b = 462.88(4), c = 801.93(7) pm, wR2 = 0.0487, 452 F2 values, 20 variable parameters for NP-CePtSn, and ZrNiAl type, P6̅2m, a = 756.919(5), c = 415.166(4) pm, wR2 = 0.0546, 252 F2 values, 14 variable parameters for HP-CePtSn. Both modifications are built up from platinumcentered trigonal prisms. Together, the platinum and tin atoms form different three-dimensional [PtSn] networks in which the cerium atoms fill channels. The crystal chemistry and chemical bonding of NP- and HP-CePtSn is discussed. Susceptibility measurements of HP-CePtSn indicate Curie-Weiss behavior above 40 K with an experimental magnetic moment of 2.55(1) μB/Ce atom, indicating trivalent cerium. No magnetic ordering could be detected down to 2 K.

Ferromagnetic Ordering in CeZnSn

2009 ◽  
Vol 64 (2) ◽  
pp. 175-183 ◽  
Author(s):  
Wilfried Hermes ◽  
Samir F. Matar ◽  
Thomas Harmening ◽  
Ute Ch. Rodewald ◽  
Matthias Eul ◽  
...  
Keyword(s):  
Magnetic Moments ◽  
Magnetic Hyperfine Field ◽  
Induction Melting ◽  
X Ray ◽  
Magnetic Structures ◽  
Bonding Analysis ◽  
Ferromagnetic Ground State ◽  
Weak Interlayer ◽  
Ferromagnetic Ordering ◽  
Experimental Magnetic Moment

The stannide CeZnSn was obtained in X-ray-pure form by induction-melting of the elements in a sealed tantalum ampoule. CeZnSn crystallizes with the YPtAs-type structure, space group P63/mmc, a = 456.7(3), c = 1673.8(5) pm, wR2 = 0.0862, 259 F2 values, and 12 variables. The zinc and tin atoms build up puckered Zn3Sn3 hexagons (Zn-Sn 271 pm) with weak interlayer Zn-Zn interactions (323 pm). Susceptibility measurements of CeZnSn reveal modified Curie-Weiss behavior above 50 K with an experimental magnetic moment of 2.77(1) μB / Ce atom. The cerium magnetic moments order ferromagnetically at TC = 5.2(1) K. 119Sn Mössbauer spectra show a single tin site at an isomer shift of δ = 1.967(4) mm/s subjected to a small quadrupole splitting of ΔEQ = 0.41(2) mm/s at 40 K. At 4.2 K a magnetic hyperfine field of 0.872(5) T is transferred to the tin site. From DFT scalar relativistic calculations of the electronic and magnetic structures, chemical bonding analysis reveals on one hand a weaker bonding of Zn than of Sn with the cerium substructures with a twice stronger Ce1-Sn bond compared to Ce2-Sn. On the other hand, a ferromagnetic ground state is identified from total energy differences in agreement with experiment

Synthesis, Structure, and Magnetic Properties of EuAgCd and YbAgCd

2001 ◽  
Vol 56 (7) ◽  
pp. 598-603 ◽  
Author(s):  
◽  
Gunter Kotzyba ◽  
Rolf-Dieter Hoffmann ◽  
Rainer Pöttgen
Keyword(s):  
High Frequency ◽  
Small Difference ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dimensional Network ◽  
Pauli Paramagnetism ◽  
Long Range Ordering ◽  
Ferromagnetic Ordering ◽  
Experimental Magnetic Moment

Abstract New intermetallic compounds EuAgCd and YbAgCd were synthesized in quantitative yield by reaction of the elements in sealed tantalum tubes in a high-frequency furnace. Both com­ pounds were investigated by X-ray diffraction on powders and single crystals: KHg2 type, Imma, a = 490.41(8), b = 771.0(1), c = 834.4(2) pm, wR2 = 0.0624, 255 F2 values, 12 variables for EuAgCd, and MgZn2 type, Pb3/mmc, a = 584.66(5), c = 946.83(9) pm, wR2 = 0.0502, 187 F2 values, 11 variables for YbAgCd. Owing to the very small difference in scattering power, no long range ordering of the silver and cadmium atoms is evident from the X-ray data, although Ag-Cd ordering is expected. The silver and cadmium atoms randomly occupy the mercury and zinc positions of the KHg2 and MgZn2 type structures, respectively. In EuAgCd the [AgCd] substructure consists of strongly puckered, orthorhombically distorted Ag3 Cd3 hexagons, while a three-dimensional network of face-and comer-sharing tetrahedra is observed in YbAgCd. The rare earth atoms fill the space between the Ag3 Cd3 hexagons (EuAgCd) or within the three-dimensional tetrahedral network (YbAgCd). Magnetic susceptibility measurements in­ dicate Pauli paramagnetism for YbAgCd and Curie-Weiss behavior above 60 K for EuAgCd with an experimental magnetic moment of 7.82(3) μB/Eu indicating divalent ytterbium and europium. Ferromagnetic ordering at Tc = 28.0(5) K is observed for EuAgCd. At 2 K and 5 T the saturation magnetization is 5.85(5) μB/Eu.

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