Electrical Resistivity of Some Neptunium Chalcogenides

Blaise, A.; Damien, D.; Mulak, Jacek

doi:10.1002/pssa.2210720256

Cited by 7 publications

(4 citation statements)

References 5 publications

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“…With Np···Np distances in both structures longer than 4.0 Å, well in excess of the Hill limit, the observed ordering temperatures are consistent with the presence of localized moments. Previous studies on the magnetic susceptibility of Np 3 Se 5 found no evidence for magnetic ordering down to temperatures as low as 4.2 K; , however, note that the published figure in the previous study does not include data for the temperature range 5 to 30 K, the range over which the cusp is observed in our data. In addition, a previous 237 Np Mössbauer study of Np 3 S 5 included spectra obtained at 77 and 4.2 K .…”

Section: Resultscontrasting

confidence: 80%

“…In our magnetic susceptibility data the cusp for Np 3 S 5 is much more pronounced than that for Np 3 Se 5 , which may indicate only one sublattice is ordering in the latter material. For comparative interest, NpSe 3 , which contains only Np 4+ , orders ferromagnetically at 51 K with a second ordering at 18 K . In contrast, Np 2 Se 3 , which contains exclusively Np 3+ , shows no evidence of magnetic splitting in the Mössbauer data obtained at 4.2 K .…”

Section: Resultsmentioning

confidence: 97%

“…The smaller value of the contribution measured for Np 3 S 5 compared to Np 3 Se 5 results in the offset of the two susceptibility curves (Figure ). An understanding of the large difference in the χ 0 terms determined for the two samples may lie in published resistivity measurements that show Np 3 S 5 to be a semiconductor whereas Np 3 Se 5 has an order of magnitude lower resistivity at 298 K and appears to be more semimetallic than semiconducting . This suggests that the larger temperature-independent paramagnetic term for Np 3 Se 5 results from Pauli paramagnetism, which arises from a high density of states with a tendency for 5f band formation.…”

Section: Resultsmentioning

confidence: 99%

“…), respectively. , U 3 S 5 is a semiconductor and ferromagnet ( T c = 29 K) that displays a large negative magnetoresistance effect. ,, U 3 Se 5 is also a semiconductor; it orders ferromagnetically below 24 K. , U 3 Te 5 adopts a different structure type . In contrast, Np 3 Q 5 (Q = S, Se) have been identified only from powder X-ray diffraction data from which it was deduced that they are isostructural with U 3 S 5 . ,− , Electrical resistivity measurements on a cold-pressed powder pellet have shown that Np 3 S 5 is a semiconductor, whereas Np 3 Se 5 exhibits semimetallic behavior . There are no reliable magnetic data for Np 3 Q 5 , although 237 Np Mössbauer measurements at 4.2 K have suggested that the magnetic moment of Np should order at low temperatures. , …”

Section: Introductionmentioning

confidence: 99%

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Syntheses, Structures, and Magnetic Properties of Np₃S₅ and Np₃Se₅

et al. 2010

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Black prisms of Np(3)Q(5) (Q = S, Se) have been synthesized by the stoichiometric reactions between Np and Q at 1173 K in a CsCl flux. The structures of these compounds were characterized by single-crystal X-ray diffraction methods. The Np(3)Q(5) compounds are isostructural with U(3)Q(5). The structure of Np(3)Q(5) is constructed from layers of Np(1)Q(8) distorted bicapped trigonal prisms that share faces with each other on bc planes. Each Np(1)Q(8) layer further shares Q(2) edges with two adjacent identical neighbors to form a three-dimensional framework. The space inside each channel within this framework is filled by one single edge-sharing Np(2)Q(7) distorted 7-octahedron chain running along the b axis. Magnetic susceptibility measurements show that Np(3)S(5) and Np(3)Se(5) have antiferromagnetic orderings at 35(1) and 36(1) K, respectively. Above the magnetic ordering temperatures, both Np(3)S(5) and Np(3)Se(5) behave as typical Curie-Weiss paramagnets. The effective moments obtained from the fit of the magnetic data to a modified Curie-Weiss law over the temperature range 70 to 300 K are 2.7(2) μ(B) (Np(3)S(5)) and 2.9(2) μ(B) (Np(3)Se(5)).

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Section: Resultscontrasting

confidence: 80%

Section: Resultsmentioning

confidence: 97%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Syntheses, Structures, and Magnetic Properties of Np₃S₅ and Np₃Se₅

et al. 2010

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Investigating Actinyl Oxo Cations by X‐ray Absorption Spectroscopy

et al. 2003

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Early actinide elements (from U to Am) have the ability to form linear trans-dioxo complexes with formal valence of the actinide being equal to (V) or (VI). For instance, the ubiquity of the uranyl cation in uranium aqueous chemistry is the basis for its very important industrial and environmental concerns. As a result, the physical chemistry of the actinyl moieties has been the subject of constantly growing investigations. Among all the spectroscopic probes, X-ray absorption spectroscopy is a particularly useful element and energy-selective technique. This article reviews the investigation of molecular actinyl complexes using both XANES and EXAFS tools. The absorption edge features have long been used to characterize the frontier orbitals of the absorbing atom. In the case of actinide cations, the L III edge, located in the hard X-ray region, provides a useful fingerprint of the cation polyhedron. Tentatively, simple molecular orbital considerations together with full multiple scattering simulation codes have MICROREVIEWS: This feature introduces the readers to the author's research through a concise overview of the selected topic. Reference to important work from others in the field is included. Complementary structural data can be obtained in the EXAFS region of the absorption spectrum. In the literature, such molecular systems have been well documented from uranyl aqueous chemistry to neptunyl or plutonyl coordination complexes with oxygen donor ligands. Furthermore, complexation mechanisms upon absorption onto mineral surfaces have been increasingly investigated over the past few years. Overall, contribution of the XAS technique to a better understanding of the actinide bonding is demonstrated from various examples of the literature and the authors' data. Importance of the simulation codes in order to better describe the absorption features is also strongly underlined.

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