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Rainer Pöttgen - One of the best experts on this subject based on the ideXlab platform.
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Antiferromagnetic ordering in a mixed-valent Cerium Compound CeRuSn
Physical Review B, 2013Co-Authors: Karel Prokes, J. A. Mydosh, Oleksandr Prokhnenko, W.-d. Stein, S. Landsgesell, Wilfried Hermes, Ralf Feyerherm, Rainer PöttgenAbstract:We report the results of extensive neutron powder diffraction experiments on a ternary Compound CeRuSn in a temperature range from 2 to 520 K. At room temperature CeRuSn orders in a monoclinic structure that is related to the CeCoAl type by the doubling of the $c$-axis parameter caused by the splitting of the original single sites for each element into two sites. Upon cooling a very broad hysteretic structural transition has been observed in CeRuSn leading to the presence of higher-ordered variants having multiple $c$-axis parameters. Depending on the temperatures, one or the other variant seems to be more stable, but the sample as a whole becomes multiphase. We find also evidence for further symmetry lowering at low temperatures. CeRuSn is found to exhibit an antiferromagnetic order below ${T}_{N}=2.8(1)$ K. The order is described by two incommensurate propagation vectors ${q}_{1}=(0,0,\ensuremath{\approx}0.30)$ and ${q}_{2}=(0,0,\ensuremath{\approx}0.43)$ with respect to the doubled crystal structure variant. Although the details of the magnetic structure remain elusive, the best agreement has been found for a complicated distorted cycloidal magnetic structure with Ce moments of $\ensuremath{\approx}$0.7 ${\ensuremath{\mu}}_{B}$ being confined to the $ac$ plane.
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Solid-state 119Sn NMR and Mössbauer spectroscopic studies of the intermediate-valent stannide CeRuSn
Zeitschrift für Naturforschung B: Chemical Sciences, 2012Co-Authors: Falko M. Schappacher, Bernard Chevalier, Panchanana Khuntia, Anakot K. Rajarajan, Michael Baenitz, John A. Mydosh, Samir F. Matar, Rainer PöttgenAbstract:The ternary stannide CeRuSn is a static mixed-valent Cerium Compound with an or-dering of trivalent and intermediate-valent Cerium on two distinct crystallographic sites. 119Sn Mössbauer spectra showed two electronically almost identical tin atoms at 323 K, while at 298 K and below (77 and 4.2 K) two tin sites can clearly be distinguished. 119Sn solid state NMR experiments are performed to probe the local hyperfine fields at the two different Sn sites. 119Sn NMR powder spectra are nicely fitted with two Sn sites with nearly the same magnetic anisotropy, but with different absolute shift values. Both Sn sites are strongly affected by crossover-like transitions between 100 and 280 K. This local-site study confirms the superstructure modulations found in previous investiga-tions. Towards lower temperatures the powder spectra are broadened giving strong evidence for the antiferromagnetically ordered ground state.
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Magnetic ordering in the static intermediate-valent Cerium Compound Ce 2 RuZn 4
Physical Review B, 2008Co-Authors: Volker Eyert, Wilfried Hermes, Ernst-wilhelm Scheidt, Wolfgang Scherer, Rainer PöttgenAbstract:The low-temperature behavior of Ce2RuZn4 has been investigated. Specific heat and magnetic susceptibility data reveal an antiferromagnetic transition at a Neel temperature of 2 K. Ce2RuZn4 is a static intermediate-valent Compound with two crystallographically independent Cerium atoms. The magnetic data clearly show that only one Cerium site is magnetic (Ce^3+), while the second one carries no magnetic moment. The experimental data are interpreted with the help of first principles electronic structure calculations using density functional theory and the augmented spherical wave method. The calculations reveal the occurrence of two different Cerium sites, which are characterized by strongly localized magneticmoments and strong Ce-Ru bonding, respectively.Comment: 6 pages, 9 figures, more information at http://www.physik.uni-augsburg.de/~eyert
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magnetic ordering in the static intermediate valent Cerium Compound ce 2 ruzn 4
Physical Review B, 2008Co-Authors: Volker Eyert, Wilfried Hermes, Ernst-wilhelm Scheidt, Wolfgang Scherer, Rainer PöttgenAbstract:The low-temperature behavior of ${\text{Ce}}_{2}{\text{RuZn}}_{4}$ has been investigated. Specific-heat and magnetic-susceptibility data reveal an antiferromagnetic transition at a N\'eel temperature of 2 K. ${\text{Ce}}_{2}{\text{RuZn}}_{4}$ is a static intermediate-valent Compound with two crystallographically independent Cerium atoms. The magnetic data clearly show that only one Cerium site is magnetic $({\text{Ce}}^{3+})$, while the second one carries no magnetic moment. The experimental data are interpreted with the help of first-principles electronic structure calculations using density-functional theory and the augmented spherical wave method. The calculations reveal the occurrence of two different Cerium sites, which are characterized by strongly localized magnetic moments and strong Ce-Ru bonding.
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trivalent intermediate valent Cerium ordering in cerusn a static intermediate valent Cerium Compound with a superstructure of the cecoal type
Zeitschrift für anorganische und allgemeine Chemie, 2007Co-Authors: Jan F Riecken, Wilfried Hermes, Falko M. Schappacher, B Chevalier, Rolfdieter Hoffmann, Rainer PöttgenAbstract:New equiatomic stannide CeRuSn was synthesized from the elements by arc-melting. CeRuSn was investigated by X-ray powder and single crystal diffraction: C2/m, a = 1156.1(4), b = 475.9(2) and c = 1023.3(4) pm, β = 102.89(3)°, wR2 = 0.0466, 1229 F2 values and 38 variables. CeRuSn adopts a superstructure of the monoclinic CeCoAl type through a doubling of the subcell c axis. In the superstructure two crystallographically independent Cerium sites occur. Based on the interatomic distances the two sites can be assigned to trivalent Ce2 and intermediate valent Ce1. This trivalent-intermediate valent Cerium ordering is underlined by magnetic susceptibility measurements χm(T): below 150 K χm, measured with decreasing temperature, follows a Curie-Weiss law χm = Cm/(T–θp) giving Cm = 0.38 emuK/mol as Curie constant per CeRuSn mol; a value showing that only half of the Cerium atoms are trivalent in CeRuSn (Cm = 0.807 emuK/mol for one free Ce3+ ion). A remarkable feature of the CeRuSn structure are the short Ce1–Ru1 (233 pm) and Ce1–Ru2 (246 pm) distances. The crystal chemistry of CeRuSn is discussed on the basis of a group-subgroup scheme.
Wilfried Hermes - One of the best experts on this subject based on the ideXlab platform.
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Antiferromagnetic ordering in a mixed-valent Cerium Compound CeRuSn
Physical Review B, 2013Co-Authors: Karel Prokes, J. A. Mydosh, Oleksandr Prokhnenko, W.-d. Stein, S. Landsgesell, Wilfried Hermes, Ralf Feyerherm, Rainer PöttgenAbstract:We report the results of extensive neutron powder diffraction experiments on a ternary Compound CeRuSn in a temperature range from 2 to 520 K. At room temperature CeRuSn orders in a monoclinic structure that is related to the CeCoAl type by the doubling of the $c$-axis parameter caused by the splitting of the original single sites for each element into two sites. Upon cooling a very broad hysteretic structural transition has been observed in CeRuSn leading to the presence of higher-ordered variants having multiple $c$-axis parameters. Depending on the temperatures, one or the other variant seems to be more stable, but the sample as a whole becomes multiphase. We find also evidence for further symmetry lowering at low temperatures. CeRuSn is found to exhibit an antiferromagnetic order below ${T}_{N}=2.8(1)$ K. The order is described by two incommensurate propagation vectors ${q}_{1}=(0,0,\ensuremath{\approx}0.30)$ and ${q}_{2}=(0,0,\ensuremath{\approx}0.43)$ with respect to the doubled crystal structure variant. Although the details of the magnetic structure remain elusive, the best agreement has been found for a complicated distorted cycloidal magnetic structure with Ce moments of $\ensuremath{\approx}$0.7 ${\ensuremath{\mu}}_{B}$ being confined to the $ac$ plane.
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Magnetic ordering in the static intermediate-valent Cerium Compound Ce 2 RuZn 4
Physical Review B, 2008Co-Authors: Volker Eyert, Wilfried Hermes, Ernst-wilhelm Scheidt, Wolfgang Scherer, Rainer PöttgenAbstract:The low-temperature behavior of Ce2RuZn4 has been investigated. Specific heat and magnetic susceptibility data reveal an antiferromagnetic transition at a Neel temperature of 2 K. Ce2RuZn4 is a static intermediate-valent Compound with two crystallographically independent Cerium atoms. The magnetic data clearly show that only one Cerium site is magnetic (Ce^3+), while the second one carries no magnetic moment. The experimental data are interpreted with the help of first principles electronic structure calculations using density functional theory and the augmented spherical wave method. The calculations reveal the occurrence of two different Cerium sites, which are characterized by strongly localized magneticmoments and strong Ce-Ru bonding, respectively.Comment: 6 pages, 9 figures, more information at http://www.physik.uni-augsburg.de/~eyert
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magnetic ordering in the static intermediate valent Cerium Compound ce 2 ruzn 4
Physical Review B, 2008Co-Authors: Volker Eyert, Wilfried Hermes, Ernst-wilhelm Scheidt, Wolfgang Scherer, Rainer PöttgenAbstract:The low-temperature behavior of ${\text{Ce}}_{2}{\text{RuZn}}_{4}$ has been investigated. Specific-heat and magnetic-susceptibility data reveal an antiferromagnetic transition at a N\'eel temperature of 2 K. ${\text{Ce}}_{2}{\text{RuZn}}_{4}$ is a static intermediate-valent Compound with two crystallographically independent Cerium atoms. The magnetic data clearly show that only one Cerium site is magnetic $({\text{Ce}}^{3+})$, while the second one carries no magnetic moment. The experimental data are interpreted with the help of first-principles electronic structure calculations using density-functional theory and the augmented spherical wave method. The calculations reveal the occurrence of two different Cerium sites, which are characterized by strongly localized magnetic moments and strong Ce-Ru bonding.
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trivalent intermediate valent Cerium ordering in cerusn a static intermediate valent Cerium Compound with a superstructure of the cecoal type
Zeitschrift für anorganische und allgemeine Chemie, 2007Co-Authors: Jan F Riecken, Wilfried Hermes, Falko M. Schappacher, B Chevalier, Rolfdieter Hoffmann, Rainer PöttgenAbstract:New equiatomic stannide CeRuSn was synthesized from the elements by arc-melting. CeRuSn was investigated by X-ray powder and single crystal diffraction: C2/m, a = 1156.1(4), b = 475.9(2) and c = 1023.3(4) pm, β = 102.89(3)°, wR2 = 0.0466, 1229 F2 values and 38 variables. CeRuSn adopts a superstructure of the monoclinic CeCoAl type through a doubling of the subcell c axis. In the superstructure two crystallographically independent Cerium sites occur. Based on the interatomic distances the two sites can be assigned to trivalent Ce2 and intermediate valent Ce1. This trivalent-intermediate valent Cerium ordering is underlined by magnetic susceptibility measurements χm(T): below 150 K χm, measured with decreasing temperature, follows a Curie-Weiss law χm = Cm/(T–θp) giving Cm = 0.38 emuK/mol as Curie constant per CeRuSn mol; a value showing that only half of the Cerium atoms are trivalent in CeRuSn (Cm = 0.807 emuK/mol for one free Ce3+ ion). A remarkable feature of the CeRuSn structure are the short Ce1–Ru1 (233 pm) and Ce1–Ru2 (246 pm) distances. The crystal chemistry of CeRuSn is discussed on the basis of a group-subgroup scheme.
B. D. Padalia - One of the best experts on this subject based on the ideXlab platform.
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Ce2Ni3Si5: A mixed-valence Cerium Compound.
Physical review. B Condensed matter, 1992Co-Authors: Chandan Mazumdar, R. Nagarajan, S. K. Dhar, L. C. Gupta, R. Vijayaraghavan, B. D. PadaliaAbstract:The results of electrical resistivity (4.2-300 K), magnetic susceptibility (5-300 K) and specific heat (2-20 K) are reported on the ternary orthorhombic rare-earth Compound Ce2Ni3Si5. The resistivity of the material is nearly temperature independent above 120 K unlike that of a normal metallic material. The magnetic contribution to resistivity shows a broad maximum around 200 K. At low temperatures, the resistivity follows a T2 behavior in the temperature range 4-13 K. The inverse magnetic susceptibility deviates from Curie-Weiss behavior below 80 K where it exhibits a broad maximum in the chi vs T curve. Specific heat measurements (2-20 K) give a value of gamma almost-equal-to 62 mJ/Ce mol K2 which is similar in magnitude to those encountered in valence-fluctuating systems. From these observations we conclude that Ce2Ni3Si5 is a Ce-based valence-fluctuation Compound
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ce2ni3si5 a mixed valence Cerium Compound
Physical Review B, 1992Co-Authors: Chandan Mazumdar, R. Nagarajan, S. K. Dhar, L. C. Gupta, R. Vijayaraghavan, B. D. PadaliaAbstract:The results of electrical resistivity (4.2--300 K), magnetic susceptibility (5--300 K) and specific heat (2--20 K) are reported on the ternary orthorhombic rare-earth Compound ${\mathrm{Ce}}_{2}$${\mathrm{Ni}}_{3}$${\mathrm{Si}}_{5}$. The resistivity of the material is nearly temperature independent above 120 K unlike that of a normal metallic material. The magnetic contribution to resistivity shows a broad maximum around 200 K. At low temperatures, the resistivity follows a ${\mathit{T}}^{2}$ behavior in the temperature range 4--13 K. The inverse magnetic susceptibility deviates from Curie-Weiss behavior below 80 K where it exhibits a broad maximum in the \ensuremath{\chi} vs T curve. Specific heat measurements (2--20 K) give a value of \ensuremath{\gamma}\ensuremath{\approxeq}62 mJ/Ce mol ${\mathrm{K}}^{2}$ which is similar in magnitude to those encountered in valence-fluctuating systems. From these observations we conclude that ${\mathrm{Ce}}_{2}$${\mathrm{Ni}}_{3}$${\mathrm{Si}}_{5}$ is a Ce-based valence-fluctuation Compound.
Volker Eyert - One of the best experts on this subject based on the ideXlab platform.
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Magnetic ordering in the static intermediate-valent Cerium Compound Ce 2 RuZn 4
Physical Review B, 2008Co-Authors: Volker Eyert, Wilfried Hermes, Ernst-wilhelm Scheidt, Wolfgang Scherer, Rainer PöttgenAbstract:The low-temperature behavior of Ce2RuZn4 has been investigated. Specific heat and magnetic susceptibility data reveal an antiferromagnetic transition at a Neel temperature of 2 K. Ce2RuZn4 is a static intermediate-valent Compound with two crystallographically independent Cerium atoms. The magnetic data clearly show that only one Cerium site is magnetic (Ce^3+), while the second one carries no magnetic moment. The experimental data are interpreted with the help of first principles electronic structure calculations using density functional theory and the augmented spherical wave method. The calculations reveal the occurrence of two different Cerium sites, which are characterized by strongly localized magneticmoments and strong Ce-Ru bonding, respectively.Comment: 6 pages, 9 figures, more information at http://www.physik.uni-augsburg.de/~eyert
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magnetic ordering in the static intermediate valent Cerium Compound ce 2 ruzn 4
Physical Review B, 2008Co-Authors: Volker Eyert, Wilfried Hermes, Ernst-wilhelm Scheidt, Wolfgang Scherer, Rainer PöttgenAbstract:The low-temperature behavior of ${\text{Ce}}_{2}{\text{RuZn}}_{4}$ has been investigated. Specific-heat and magnetic-susceptibility data reveal an antiferromagnetic transition at a N\'eel temperature of 2 K. ${\text{Ce}}_{2}{\text{RuZn}}_{4}$ is a static intermediate-valent Compound with two crystallographically independent Cerium atoms. The magnetic data clearly show that only one Cerium site is magnetic $({\text{Ce}}^{3+})$, while the second one carries no magnetic moment. The experimental data are interpreted with the help of first-principles electronic structure calculations using density-functional theory and the augmented spherical wave method. The calculations reveal the occurrence of two different Cerium sites, which are characterized by strongly localized magnetic moments and strong Ce-Ru bonding.
Gunter Kotzyba - One of the best experts on this subject based on the ideXlab platform.
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ce2ni2cd a new intermediate valent Cerium Compound
IEEE Journal of Solid-state Circuits, 2000Co-Authors: Dirk Niepmann, Rainer Pöttgen, Bernd Künnen, Gunter KotzybaAbstract:Abstract Ce 2 Ni 2 Cd was synthesized by reacting the elements in a sealed tantalum tube using a high-frequency furnace with a water-cooled sample chamber. The structure was refined from single-crystal X-ray data: ordered U 3 Si 2 type, P 4/ mbm , a =755.67(8) pm, c =375.14(6) pm, w R 2=0.0408, 232 F 2 values, and 13 parameters. A refinement of the occupancy parameters showed defects on the nickel site, resulting in a composition of Ce 2 Ni 1.88(1) Cd for the crystal investigated. The structure may be described as an intergrowth of CsCl and AlB 2 related slabs of compositions CeCd and CeNi 2 . Magnetic susceptibility measurements indicate intermediate-valent behavior of the Cerium atoms. The susceptibility data can be fit to a modified Curie–Weiss expression with Θ P =−5.2(2) K, μ exp =0.79(3) μ B /Ce, and a temperature-independent contribution χ 0 =67.5(7)×10 −9 m 3 /mol. Temperature-dependent resistivity measurements indicate metallic behavior with a specific resistivity of 140±20 μΩ cm at room temperature. Below 50 K the specific resistivity reveals a T 2 dependence with ρ 0 =84.4(1) μΩ cm and A =0.0056(1) (μΩ cm)/K 2 .
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Ce2Ni2Cd—A New Intermediate-Valent Cerium Compound
Journal of Solid State Chemistry, 2000Co-Authors: Dirk Niepmann, Rainer Pöttgen, Bernd Künnen, Gunter KotzybaAbstract:Abstract Ce 2 Ni 2 Cd was synthesized by reacting the elements in a sealed tantalum tube using a high-frequency furnace with a water-cooled sample chamber. The structure was refined from single-crystal X-ray data: ordered U 3 Si 2 type, P 4/ mbm , a =755.67(8) pm, c =375.14(6) pm, w R 2=0.0408, 232 F 2 values, and 13 parameters. A refinement of the occupancy parameters showed defects on the nickel site, resulting in a composition of Ce 2 Ni 1.88(1) Cd for the crystal investigated. The structure may be described as an intergrowth of CsCl and AlB 2 related slabs of compositions CeCd and CeNi 2 . Magnetic susceptibility measurements indicate intermediate-valent behavior of the Cerium atoms. The susceptibility data can be fit to a modified Curie–Weiss expression with Θ P =−5.2(2) K, μ exp =0.79(3) μ B /Ce, and a temperature-independent contribution χ 0 =67.5(7)×10 −9 m 3 /mol. Temperature-dependent resistivity measurements indicate metallic behavior with a specific resistivity of 140±20 μΩ cm at room temperature. Below 50 K the specific resistivity reveals a T 2 dependence with ρ 0 =84.4(1) μΩ cm and A =0.0056(1) (μΩ cm)/K 2 .