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Title: Chemical bonding in EuTGe (T=Ni, Pd, Pt) and physical properties of EuPdGe

Abstract

EuPdGe was prepared from the elements by reaction in a sealed tantalum tube in a high-frequency furnace. Magnetic susceptibility measurements show Curie-Weiss behavior above 60 K with an experimental magnetic moment of 8.0(1){mu} {sub B}/Eu indicating divalent europium. At low external fields antiferromagnetic ordering is observed at T {sub N}=8.5(5) K. Magnetization measurements indicate a metamagnetic transition at a critical field of 1.5(2) T and a saturation magnetization of 6.4(1){mu} {sub B}/Eu at 5 K and 5.5 T. EuPdGe is a metallic conductor with a room-temperature value of 5000{+-}500 {mu}{omega} cm for the specific resistivity. {sup 151}Eu Moessbauer spectroscopic experiments show a single europium site with an isomer shift of {delta}=-9.7(1) mm/s at 78 K. At 4.2 K full magnetic hyperfine field splitting with a hyperfine field of B=20.7(5) T is observed. Density functional calculations show the similarity of the electronic structures of EuPdGe and EuPtGe. T-Ge interactions (T=Pd, Pt) exist in both compounds. An ionic formula splitting Eu{sup 2+} T {sup 0}Ge{sup 2-} seems more appropriate than Eu{sup 2+} T {sup 2+}Ge{sup 4-} accounting for the bonding in both compounds. Geometry optimizations of EuTGe (T=Ni, Pt, Pd) show weak energy differences between the two structural types. - Graphical abstract:more » Cutouts of the [PdGe] and [PtGe] polyanions in the structures of EuPdGe and EuPtGe. Atom designations and some relevant interatomic distances are given.« less

Authors:
 [1];  [1];  [2];  [3];  [3];  [3];  [4];  [5]
  1. UMR 6226 Sciences Chimiques de Rennes, Universite de Rennes 1-ENSC Rennes-CNRS, Avenue du General Leclerc, F-35042 Rennes Cedex (France)
  2. UMR 6226 Sciences Chimiques de Rennes, Universite de Rennes 1-ENSC Rennes-CNRS, Avenue du General Leclerc, F-35042 Rennes Cedex (France), E-mail: halet@univ-rennes1.fr
  3. Institut fuer Physikalische Chemie, Universitaet Muenster, Corrensstrasse 30, D-48149 Muenster (Germany)
  4. Institut fuer Anorganische und Analytische Chemie, Universitaet Muenster, Corrensstrasse 30, D-48149 Muenster (Germany)
  5. Institut fuer Anorganische und Analytische Chemie, Universitaet Muenster, Corrensstrasse 30, D-48149 Muenster (Germany), E-mail: pottgen@uni-muenster.de
Publication Date:
OSTI Identifier:
21015680
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 180; Journal Issue: 2; Other Information: DOI: 10.1016/j.jssc.2006.11.013; PII: S0022-4596(06)00603-7; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ACCOUNTING; ANTIFERROMAGNETISM; CHEMICAL BONDS; CRITICAL FIELD; DENSITY FUNCTIONAL METHOD; ELECTRONIC STRUCTURE; EUROPIUM ALLOYS; EUROPIUM COMPOUNDS; EUROPIUM IONS; GERMANIUM ALLOYS; INTERATOMIC DISTANCES; INTERMETALLIC COMPOUNDS; ISOMER SHIFT; MAGNETIC MOMENTS; MAGNETIC SUSCEPTIBILITY; MAGNETIZATION; MOESSBAUER EFFECT; NICKEL ALLOYS; PALLADIUM ALLOYS; PLATINUM ALLOYS; TEMPERATURE RANGE 0065-0273 K; TEMPERATURE RANGE 0273-0400 K

Citation Formats

Rocquefelte, Xavier, Gautier, Regis, Halet, Jean-Francois, Muellmann, Ralf, Rosenhahn, Carsten, Mosel, Bernd D., Kotzyba, Gunter, and Poettgen, Rainer. Chemical bonding in EuTGe (T=Ni, Pd, Pt) and physical properties of EuPdGe. United States: N. p., 2007. Web. doi:10.1016/j.jssc.2006.11.013.
Rocquefelte, Xavier, Gautier, Regis, Halet, Jean-Francois, Muellmann, Ralf, Rosenhahn, Carsten, Mosel, Bernd D., Kotzyba, Gunter, & Poettgen, Rainer. Chemical bonding in EuTGe (T=Ni, Pd, Pt) and physical properties of EuPdGe. United States. doi:10.1016/j.jssc.2006.11.013.
Rocquefelte, Xavier, Gautier, Regis, Halet, Jean-Francois, Muellmann, Ralf, Rosenhahn, Carsten, Mosel, Bernd D., Kotzyba, Gunter, and Poettgen, Rainer. Thu . "Chemical bonding in EuTGe (T=Ni, Pd, Pt) and physical properties of EuPdGe". United States. doi:10.1016/j.jssc.2006.11.013.
@article{osti_21015680,
title = {Chemical bonding in EuTGe (T=Ni, Pd, Pt) and physical properties of EuPdGe},
author = {Rocquefelte, Xavier and Gautier, Regis and Halet, Jean-Francois and Muellmann, Ralf and Rosenhahn, Carsten and Mosel, Bernd D. and Kotzyba, Gunter and Poettgen, Rainer},
abstractNote = {EuPdGe was prepared from the elements by reaction in a sealed tantalum tube in a high-frequency furnace. Magnetic susceptibility measurements show Curie-Weiss behavior above 60 K with an experimental magnetic moment of 8.0(1){mu} {sub B}/Eu indicating divalent europium. At low external fields antiferromagnetic ordering is observed at T {sub N}=8.5(5) K. Magnetization measurements indicate a metamagnetic transition at a critical field of 1.5(2) T and a saturation magnetization of 6.4(1){mu} {sub B}/Eu at 5 K and 5.5 T. EuPdGe is a metallic conductor with a room-temperature value of 5000{+-}500 {mu}{omega} cm for the specific resistivity. {sup 151}Eu Moessbauer spectroscopic experiments show a single europium site with an isomer shift of {delta}=-9.7(1) mm/s at 78 K. At 4.2 K full magnetic hyperfine field splitting with a hyperfine field of B=20.7(5) T is observed. Density functional calculations show the similarity of the electronic structures of EuPdGe and EuPtGe. T-Ge interactions (T=Pd, Pt) exist in both compounds. An ionic formula splitting Eu{sup 2+} T {sup 0}Ge{sup 2-} seems more appropriate than Eu{sup 2+} T {sup 2+}Ge{sup 4-} accounting for the bonding in both compounds. Geometry optimizations of EuTGe (T=Ni, Pt, Pd) show weak energy differences between the two structural types. - Graphical abstract: Cutouts of the [PdGe] and [PtGe] polyanions in the structures of EuPdGe and EuPtGe. Atom designations and some relevant interatomic distances are given.},
doi = {10.1016/j.jssc.2006.11.013},
journal = {Journal of Solid State Chemistry},
number = 2,
volume = 180,
place = {United States},
year = {Thu Feb 15 00:00:00 EST 2007},
month = {Thu Feb 15 00:00:00 EST 2007}
}
  • The crystallographic, electronic transport and thermal properties of Ca{sub 2}PdGe{sub 3} and Ca{sub 2}PtGe{sub 3} are reported. The compounds crystalize in an ordered variant of the AlB{sub 2} crystal structure, in space group P6/mmm, with the lattice parameters a = 8.4876(4) Å/8.4503(5) Å and c = 4.1911(3) Å/4.2302(3) Å for Ca{sub 2}PdGe{sub 3} and Ca{sub 2}PtGe{sub 3}, respectively. The resistivity data exhibit metallic behavior with residual-resistivity-ratios (RRR) of 13 for Ca{sub 2}PdGe{sub 3} and 6.5 for Ca{sub 2}PtGe{sub 3}. No superconducting transition is observed down to 0.4 K. Specific heat studies reveal similar values of the Debye temperatures and Sommerfeldmore » coefficients: Θ{sub D} = 298 K, γ = 4.1 mJ mol{sup −1} K{sup −2} and Θ{sub D} = 305 K, γ = 3.2 mJ mol{sup −1} K{sup −2} for Ca{sub 2}PdGe{sub 3} and Ca{sub 2}PtGe{sub 3}, respectively. The low value of γ is in agreement with the electronic structure calculations.« less
  • Eleven new compounds, R Ni{sub 2}Cd{sub 20} (R=Y, La–Nd, Sm, Gd, Tb) and R Pd{sub 2}Cd{sub 20} (R=Ce, Pr, Sm), were grown as single crystals in high temperature cadmium-rich solutions. They crystallize in the cubic CeCr{sub 2}Al{sub 20}-type structure (Fd3{sup ¯}m, Z=8) as characterized by measurements of powder X-ray diffraction. Electrical resistivity, magnetization, and specific heat measurements were performed on R Ni{sub 2}Cd{sub 20} (R=Y, La–Nd, Sm, Gd, Tb) single crystals. Whereas YNi{sub 2}Cd{sub 20} and LaNi{sub 2}Cd{sub 20} exhibit unremarkable metallic behavior, when magnetic moments from localized 4f electron states (Gd{sup 3+}–Tb{sup 3+}) are embedded into this host, theymore » exhibit ferromagnetic order with values of the Curie temperature T{sub C} for R Ni{sub 2}Cd{sub 20} (R=Gd, and Tb) which scale with the de Gennes factor. - Graphical abstract: Specific heat divided by temperature C/T vs. T for single crystals of R Ni{sub 2}Cd{sub 20} (R=Y, La–Nd, Gd, and Tb). Left inset: Low temperature C/T vs. T{sup 2} for LaNi{sub 2}Cd{sub 20}. The solid line represents a linear fit of the data. Right inset: Low-temperature C/T data vs. T for R=Ce–Nd, Gd, and Tb; magnetic ordering temperatures are indicated by arrows. - Highlights: • R Ni{sub 2}Cd{sub 20} (R=Y, La–Nd, Sm, Gd, Tb) single crystals synthesized for the first time. • R Pd{sub 2}Cd{sub 20} (R=Ce, Pr, Sm) single crystals synthesized for the first time. • Single crystals are of good metallurgical quality (large RRR values). • NdNi{sub 2}Cd{sub 20} orders antiferromagnetically at T{sub N}=1.5 K. • R Ni{sub 2}Cd{sub 20} (R=Sm, Gd, Tb) order ferromagnetically.« less
  • The bonding of H to the (111) surfaces of Ni, Pd, and Pt has been studied using angle-resolved photoelectron spectroscopy. H adsorbed onto a cooled substrate produces photoemission spectra characteristic of chemisorption. In this state the H atoms form an ordered overlayer. Heating the chemisorbed layer to approx.300 K results in an irreversible transition of the H atoms into a subsurface site.
  • A group of ternary cerium compounds Ce{sub 2}{ital T}{sub 2}In ({ital T}=Ni, Cu, Rh, Pd, Pt, and Au) has been synthesized. As found from single-crystal and powder x-ray-diffraction studies, all these phases crystallize in a primitive tetragonal structure of the Mo{sub 2}FeB{sub 2} type. Magnetic measurements (magnetization, dc and ac susceptibility) have revealed the physical properties of these intermetallics to be mainly governed by the 4{ital f}-{ital d} hybridization. Depending on the filling of the transition metal {ital d} band the ground state in Ce{sub 2}{ital T}{sub 2}In changes from a nonmagnetic to a well localized magnetic regime. It wasmore » proved that Ce{sub 2}Ni{sub 2}In and Ce{sub 2}Rh{sub 2}In are intermediate-valence systems, Ce{sub 2}Pt{sub 2}In is a strongly temperature-dependent paramagnet, whereas Ce{sub 2}Cu{sub 2}In, Ce{sub 2}Pd{sub 2}In, and Ce{sub 2}Au{sub 2}In order magnetically at low temperatures. Measurements of the electrical resistivity have corroborated the intermediate-valence behavior in Ce{sub 2}Ni{sub 2}In and Ce{sub 2}Rh{sub 2}In. In turn, the resistivity of the remaining ternaries studied was found to be determined by an interplay of Kondo scattering and crystal-field effects. For Ce{sub 2}Pt{sub 2}In which behaves like a spin-fluctuating system due to strong Kondo-type interactions a nonmagnetic heavy-fermion ground state probably occurs. {copyright} {ital 1996 The American Physical Society.}« less