Crystal Structure of Nb5P3.

Hassler, Eivind; Waltersson, Kjell; Åse, Kjell; Omfeldt, Marianne; Lagerlund, Inger; Ehrenberg, L.

doi:10.3891/acta.chem.scand.25-0129

Cited by 19 publications

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“…On the basis of their X-ray powder diffraction data, Boller and Parthe 2 reported that the Nb−P bond distance is 2.54(0) Å. The Nb−P bond distances obtained in our refinement are normal for trigonal prismatic coordinated (NbP 6 /PNb 6 ) niobium phosphides. , The local trigonal prismatic environments in NbP are only slightly distorted, with two short (2.5294(7) Å) and four longer (2.5368(4) Å) Nb−P distances. The symmetry of the distorted trigonal prisms of NbP 6 /PNb 6 is C 2 v .…”

Section: Resultsmentioning

confidence: 58%

Crystal Structure, Electrical Transport, and Magnetic Properties of Niobium Monophosphide

Xu¹,

Greenblatt²,

Emge³

et al. 1996

Inorg. Chem.

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Large single crystals of NbP have been prepared. A single-crystal X-ray diffraction study shows that it crystallizes in tetragonal symmetry with space group I4(1)md (No. 109) and lattice parameters a = 3.3324(2) Å, c = 11.3705(7) Å, and Z = 4. A full matrix least-squares refinement based on a unique data set of 285 reflections (I> 2sigma(I)) yielded R(F) = 0.017 and R(w)(F(2)) = 0.046 for nine variables. The unit cell consists of one unique Nb and one P, each in trigonal prismatic coordination with the other element. There are two short and four long bond distances of Nb-P. The Nb-Nb bond distances are significantly shorter than R(c) = 4.09 Å, the critical distance required for good Nb-Nb 4d orbital overlap for niobium metal-metal bonds. NbP shows metallic behavior with rho = 4.5 x 10(-)(5) Omega cm at room temperature. Magnetic susceptibility measurements on a collection of randomly oriented single crystals indicate very weak Pauli paramagnetism ( approximately 10(-)(5) emu/mol). A discussion of the structure as well as the physical properties of NbP compared with those of previous results are presented. The band structure of NbP based on the extended Hückel (tight-binding) calculations is presented along with an analysis that reveals that the valence band is built up from three center bonds localized within Nb(3) triangles.

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Section: Resultsmentioning

confidence: 58%

Crystal Structure, Electrical Transport, and Magnetic Properties of Niobium Monophosphide

Xu¹,

Greenblatt²,

Emge³

et al. 1996

Inorg. Chem.

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“…As regards the Nb-P binary system, no phase diagram has ever been proposed; however, six phosphides were identified in this binary system: Nb 3 P, 38) Nb 7 P 4 , 39) Nb 5 P 3 , 40) Nb 8 P 5 , 41) NbP, 42,43) and NbP 2 . 44) Among these phosphides, NbP was estimated to decompose at 1 730°C.…”

Section: The Nb-p Binary Systemmentioning

confidence: 93%

“…Thus, in this study, the thermodynamic parameters of the liquid phase were determined in such a way that the Gibbs energy of formation of the liquid phase would fit that of the bcc phase at the temperature of 2 000°C obtained from our first-principles calculations. It should be noted that, although six phosphides for the Nb-P binary system have been reported in the literature [38][39][40][41][42][43][44] as shown in Table 1, only four phosphides, namely Nb 3 P, Nb 7 P 4 , NbP, and NbP 2 , were considered in the thermodynamic analysis since the other phosphides, Nb 5 P 3 and Nb 8 P 5 , have higher energy relative to the convex hull that represents the set of tie lines connecting the formation energy of the ground states. The temperature dependency of the formation energy of NbP was evaluated based on the estimated melting temperature.…”

Section: The Nb-p Binary Systemmentioning

confidence: 99%

Thermodynamic Analysis of Phase Equilibria in the Fe–Nb–P Ternary System

et al. 2009

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A thermodynamic analysis of the Fe-Nb-P ternary system has been carried out using the CALPHAD method. Among the three binary systems present in this ternary phase diagram, the phase equilibria in the Nb-P binary system, on which very few studies have been reported, were thermodynamically analysed. The thermodynamic properties of various phosphides and of a bcc solid solution obtained from first-principles calculations were utilized in this analysis to compensate for the lack of available experimental data. By applying these procedures, a highly plausible Nb-P binary phase diagram was established over the entire composition range. The thermodynamic descriptions of the Fe-Nb and Fe-P binary systems were taken from previous studies. The thermodynamic parameters of the Fe-Nb-P ternary system were evaluated based on experimental data for the phase boundaries and estimated thermodynamic properties of the ternary phosphides obtained using first-principles calculations. The calculated phase equilibria were in good agreement with the available experimental data. From the calculated results, we confirmed that the ternary phosphide, FeNbP, took part in equilibria with most of the binary phosphides.KEY WORDS: phase diagram; thermodynamic analysis; CALPHAD; first-principles calculations. 947© 2009 ISIJ appearing in the Nb-P binary system and the ternary phosphides was evaluated using the WIEN2k software package, 10) based on the Full Potential Linearized Augmented Plane Wave (FLAPW) method with a Generalized Gradient Approximation (GGA).11) We assumed Muffin radii of 2.0 au (0.106 nm) for Fe and Nb and 1.9 au (0.1005 nm) for P, and the plane wave basis set up to the cut-off energy of 20 Ry (270 eV) was utilized in our computations.2.1.2. Free Energy of the bcc Solid Solution in the Nb-P Binary System In addition to the formation energy of the various phosphides, the Gibbs energy of formation of the bcc solid solution (a) of the Nb-P binary system was evaluated using first-principles calculations. The procedure for obtaining the Gibbs free energy of formation is explained in this section.First, 36 types of bcc-based ordered superstructures, such as D0 3 , B2, and B32, were constructed by changing the stack of pure element planes along a given direction in the parent bcc structure lattice, [12][13][14] and the total energies of those structures were calculated using the WIEN2k software package.10) Then, the energy of formation of the bccbased ordered f phase, DE f form , was obtained from the total energy by subtracting the concentration-weighted averages from the total energy of the pure elements:.......... (1) where c i is the concentration of element i. The term E f total denotes the total energy of the f superstructure, whereas the terms E total bcc-Nb and E total bcc-P refer to the total energy of bcc Nb and hypothetical bcc P, respectively. The energy of formation, DE f form , can be also expressed as the sum of effective interaction energies for clusters, such as a point, nearest and second nearest neighbor pairs, a tri...

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“…In other words, weak, partial bonds, which cannot be considered as full bonds, are often observed. Such bonds as P(3)-P(3) i, P(4)LP(5), P(4)-P(5), (Rundqvist, 1966a); NbTP 4 (Rundqvist, 1966b); Nb~P 3 (Hassler, 1971); NbsP 5 (Anugul, Pontchour & Rundqvist, 1973).…”

Section: (I) --X --½ + Y --Z (Vi) ½ -X ½ + Y ½ + Z (Ii) ½ --X ½ mentioning

confidence: 99%

High-pressure synthesis and structure of the new niobium phosphide Nb₂P₅

Kanno¹,

Kinomura²,

Koizumi³

et al. 1980

Acta Crystallogr Sect B

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Nb2P 5 was prepared by reaction of the elements at 3-5 GPa and 1273 K using a cubic-anvil-type apparatus.The crystal is orthorhombic, Pnma, with a = 16.742 (3), b = 3.3499 (6), c = 7.912 (1) A, Z = 4, and D x = 5.10 Mg m -a. The structure was refined to R = 0.037 for 1198 independent reflections. The structure of Nb2P 5 is closely related to the OsGe2-type structure. Zigzag P~ chains are additionally inserted along the b axis between the Os2Ge 4 rhombic prisms of the OsGe2-type structure. Nb2P s is a metallic conductor and shows Pauli paramagnetism.

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Crystal Structure of Nb5P3.

Cited by 19 publications

References 0 publications

Crystal Structure, Electrical Transport, and Magnetic Properties of Niobium Monophosphide

Crystal Structure, Electrical Transport, and Magnetic Properties of Niobium Monophosphide

Thermodynamic Analysis of Phase Equilibria in the Fe–Nb–P Ternary System

High-pressure synthesis and structure of the new niobium phosphide Nb₂P₅

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Crystal Structure of Nb5P3.

Cited by 19 publications

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Crystal Structure, Electrical Transport, and Magnetic Properties of Niobium Monophosphide

Crystal Structure, Electrical Transport, and Magnetic Properties of Niobium Monophosphide

Thermodynamic Analysis of Phase Equilibria in the Fe–Nb–P Ternary System

High-pressure synthesis and structure of the new niobium phosphide Nb2P5

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High-pressure synthesis and structure of the new niobium phosphide Nb₂P₅