- Crystal structure of Ce3Ni2(BN)2N and magnetic behavior of (CeNi(BN))2(CeN)x with x = 0, 1
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The new compound Ce3Ni2(BN)2N was synthesized by a modified solid state metathesis reaction. The crystal structure of Ce3Ni2(BN)2N was found to be isotypic with the superconducting compound La3Ni2(BN)2N, according to Rietveld refinements performed on X-ray powder data (I4/mmm, Z = 2, a = 3.5817(1) A, c = 20.283(1) A). Corresponding solid state reactions of mixtures composed of CeN/NiB and CeNi/BN yielded CeNi(BN) and a mixture of the two closely related layered structures (CeNi(BN)) 2(CeN)x with x = 0 and 1. Magnetization experiments on these samples revealed temperature independent paramagnetic behavior for Ce 3Ni2(BN)2N and CeNi(BN) without any magnetic ordering down to 5 K.
- Glaser, Jochen,Mori, Takao,Meyer, H.-Juergen
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- PrNi and CeNi hydrides with extremely high H-density
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The new hydrides, PrNiHx and CeNiHx were synthesized by two different techniques: at low hydrogen pressure (pH2) and elevated temperature, and at pH2 = 60 bar and room temperature. The products of both techniques have similar crystal
- Kolomiets,Miliyanchuk,Galadzhun,Havela,Vejpravova
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- Magnetic properties of new Ce-T-Mg compounds (T = Ni, Pd)
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We present results of the first investigation of ternary Ce-compounds containing a transition metal and Mg. The structure, resistivity and susceptibility of Ce2Ni2Mg, CeNi4Mg and CePdMg are reported and discussed. These compounds crystallize in the same structure as their respective In-homologues and show very similar structural parameters, but weaker strength of the Ce-4f-hybridization.
- Geibel,Klinger,Weiden,Buschinger,Steglich
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- Measurement of Seebeck effect (thermoelectric power) at high pressure up to 40 GPa
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The paper reports details of a high-pressure thermoelectric power (Seebeck effect) technique up to 40 GPa. Several different types of high-pressure cells with anvil insets are presented. The technique was applied for measurements of pressure dependence of the thermopower of several substances including elemental metals (lead, Pb; indium, In), ceriumnickel alloy, CeNi and sulphur, S. Two peculiarities in the pressure dependences of the thermopower of CeNi were found and attributed to structural transformations, near ~5 and ~10 GPa. These transitions were confirmed in direct X-ray diffraction studies. Sulphur compressed to 40 GPa exhibited a hole type conductivity and the thermopower value was about ~1 mV/K. Additionally, as an example of pressure calibration, the data on the electrical resistivity of zinc selenide, ZnSe, are given in a range of 023 GPa. These data suggest three possible scenarios of phase transitions from a rock salt (RS) high-pressure phase of ZnSe under decompression: RS→zinc blende (ZB), RS→cinnabar→ZB, and RS→wurtzite.
- Shchennikov, Vladimir V.,Ovsyannikov, Sergey V.,Manakov, Andrei Y.
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- Magnetic ground state of Ce Ni1-x Cux: A calorimetric investigation
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Ce Ni1-x Cux is a substitutional magnetic system where the interplay of the different magnetic interactions leads to the disappearance of the long-range magnetic order on the CeNi side. The existence of inhomogeneities (spin clusters or phase coexistence) has been previously detected by magnetization and muon spin relaxation (μSR) spectroscopy measurements. These inhomogeneities are always observed regardless of the different preparation methods and must, then, be considered as intrinsic. We present a detailed specific heat study in a large temperature range of 0.2 to 300 K. The analysis of these data, considering also previous neutron scattering, magnetic characterization, and μSR results, allows us to present a convenient description of the system as inhomogeneous on the nanometric scale. Two regimes are detected in the compositional range depending on the dominant Ruderman-Kittel-Kasuya-Yosida or Kondo interactions. We propose that the long-range magnetic order at low temperatures is achieved by a percolative process of magnetic clusters that become static below the freezing temperature Tf. In this scenario the existence of a quantum critical point at the magnetic-nonmagnetic crossover must be discarded. This situation should be considered as an example for other substitutional compounds with anomalous magnetic or superconducting properties.
- Marcano,Espeso,Gomez Sal,Rodriguez Fernandez,Herrero-Albillos,Bartolome
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- Effect of sintering conditions on the formation of single-phase NdMgNi4 compound and its hydrogen storage properties
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Effects of different sintering conditions on the formation of single-phase NdMgNi4 compound and its electrochemical properties have been investigated. XRD analysis shows that an ideal single-phase compound of NdMgNi4 can be synthesized by sintering the pressed tablets of mixture of Mg, Ni and NdNi powders under 973 K for 5 h; single-phase compounds of REMgNi4 (RE = La, Ce, Pr) can be synthesized in this way as well. The electrochemical properties were measured by simulated battery tests. The maximum discharge capacity of NdMgNi4 compound was about 200 mAh/g, and just 78 mAh/g for CeMgNi4 compound. NdMgNi4 compound could store 3.5 H/M of hydrogen under 2.5 MPa at 298 K, whilst it is difficult to absorb hydrogen at a higher temperature (473 K).
- Wang,Zhou, Huaiying,Zou,Yao, Qingrong
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p. 260 - 263
(2008/10/09)
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- Effect of chemical and external pressure on the structure of intermetallic compound CeNi
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Neutron powder diffraction was employed to study the structural modifications of the intermediate-valence compound CeNi at room temperature induced by either chemical or external pressure. For the first time we were able to record the diffraction pattern resulting from the pressure-induced first-order phase transition occurring in CeNi at 300 K. At pressure P = 2 GPa we observe the coexistence of two phases while only single pressure-induced phase is visible at P = 5 GPa. The results obtained are indicative of a higher symmetry of the collapsed structure as compared to the CrB-type ambient pressure structure of CeNi. The critical pressure range around 2 GPa is found to be agreement with the previous estimation derived from the thermopower measurements.
- Mirmelstein,Clementyev,Voronin,Akshentsev,Kozlenko,Kutepov,Petrovtsev,Zuev
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p. 281 - 284
(2008/10/09)
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- Electrical and thermal transport in CeNi and LaNi
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We have measured the electrical resistivity and thermal conductivity of CeNi, LaNi and La 0.15Ce 0.85Ni in the temperature range 4-400 K simultaneously on the same specimen using the TTO option in PPMS (Quantum Design) facility. Anom
- Rudajevová, Alexandra,Vasylyev, Denis,Musil, Ond?ej
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p. 758 - 759
(2008/10/09)
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- Role of the electronic state of cerium in the magnetic properties of CeNixPt1-x compounds
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We present in this work an x-ray absorption spectroscopy investigation performed at the L1,3 edges of Ce in the intermetallic compounds CeNixPt1-x. This study provides a direct microscopic probe of the cerium electronic state that is found to be trivalent up to x≤0.9 and an intermediate valence for higher Ni content. The modification of the Ce L3- and L1-edge absorption profiles has been correlated with the density of conduction electrons and with the modification of the hybridization between the orbitals of Ce and the conduction band. Our results stressed that the behavior of the CeNixPt1-x series is in agreement with the Doniach diagram only up to x≤0.9. Moreover, the transition to nonmagnetism is due to the progressive screening of the 4f shell as the result of the competition between exchange interactions and the Kondo effect and not to the change of cerium valence.
- Espeso, Jose Ignacio,Gomez Sal, Jose Carlos,Chaboy, Jesus
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- Transition from Kondo to intermediate valence regime in (La1-xCex)Ni: An ESR study
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We report on electron spin resonance (ESR) results for the series of compounds (La1-xCex)Ni doped with Gd. We show that from the Gd g-value and linewidth one can determine the concentration xc where the system goes from Ko
- Medina,Gandra,Azanha,Cardoso
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p. 9763 - 9768
(2008/10/08)
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- Formation of Kondo lattice in La1-xCexNi
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Temperature dependences of the resistivity and the susceptibility of single crystals of solid solution La1-x CexNi have been measured in the temperature range 2-300 K. We have obtained a phase diagram of La 1-x CexNi which is consisted of three parts; (1) isolated Kondo region (xa localized trivalent state, (2) fairly isolated dense Kondo region (x>0.6 and high temperature region), where the 4f electron behaves as fairly localized electron although the valence of the Ce ion is more than three and (3) Kondo lattice region (x>0.6 and low temperature region), where the 4f state becomes a delocalized state.
- Isikawa, Yosikazu,Mori, Katsunori,Fujii, Akiyoshi,Sato, Kiyoo
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p. 3165 - 3173
(2008/10/08)
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