High-pressure phases with ordered defect PbFCl-type structures in the systems V–P and Nb–P

Jeitschko, Wolfgang; Donohue, P.C.; Johnson, Vancliff

doi:10.1107/s0567740876005645

Cited by 15 publications

(6 citation statements)

References 16 publications

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“…Furthermore, the powder diffraction patterns collected on selected and crushed single crystals of the new phase indicated the pattern was different compared to the previously reported MnP 4 modifications. [7][8][9]12 Instead the collected pattern was similar to γ-FeP 4 11 crystallizing in Laue group 2/m with the monoclinic space group C2/c.…”

Section: ■ Introductionmentioning

confidence: 97%

“…Even with these difficult synthetic conditions, unidentified phases remained present in the product. 7 Using a Sn-flux, 8-MnP 4 and ultimately two other polymorphs 2-MnP 4 8 and 6-MnP 4 9 were identified with reaction temperatures ranging between 820 and 1200 K. The stacking variant "4-MnP 4 ", formed by Mn 1−x Cr x P 4 (0.3 < x < 0.7), was also obtained from a Sn-flux at high temperature (948 K). 12 Only one single-phase product of 2-MnP 4 has been obtained so far.…”

Section: ■ Introductionmentioning

confidence: 98%

“…Thus, they are named according to the stacking of layers of pentagons and hexagons formed by manganese and phosphorus: 2-MnP 4 , 8 6-MnP 4 , 9 and 8-MnP 4 . 7 A second description of the polymorphism in this compound is based on the corner-or edge-sharing TP 6 octahedra (T = transition metal), which is used to describe the crystal structure of γ-FeP 4 . 10,11 This description is visualized in Figure 1, with the octahedral units highlighted in blue.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Although a pseudobinary composition, the similarity of this stacking variant led to it being named "4-MnP 4 ." 12 The incorporation of Cr in this solid solution is an example of the many more transition metal tetraphosphides TP 4 , which are known: the CrP 4 -type (space group C2/c, T = Cr, Mo, V), 13 α-OsP 4 type (P2 1 /c, T = Ru, Os, Mg, Cd), 14 or the other FeP 4 -variants (see refs 10,11 and references therein). There exist further modifications of TP 4 with different space groups (T = Ru, Os: P1̅ :, 15 T = Re, Tc: Pbca, 16,17 and ZnP 4 : P4 1 2 1 2) 18,19 In nearly all of these compounds, layers of transition metal atoms and phosphorus atoms form the crystal structure.…”

Section: ■ Introductionmentioning

confidence: 99%

“…The starting models for the VASP calculations were the experimentally determined structures (X-ray data). [7][8][9]12 The density of states of γ-MnP 4 (Figure 7a) shows a band gap at the Fermi level, which is expected for the semiconducting material. Directly below the Fermi level, predominantly Mn 3d-states contribute to the DOS, and from −2 to −6 eV, mainly 3s and 3p states of P are present.…”

Section: ■ Introductionmentioning

confidence: 99%

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Discovery of γ-MnP₄ and the Polymorphism of Manganese Tetraphosphide

et al. 2015

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A new polymorph of MnP4 was prepared by reaction of the elements via chemical vapor transport with iodine as transporting agent. The crystal structure was refined using single-crystal diffraction data (space group Cc, no. 9, a = 5.1049(8) Å, b = 10.540(2) Å, c = 10.875(2) Å, β = 93.80(2)°). The phase is called γ-MnP4 as it is isostructural with γ-FeP4. It is the fourth reported binary polymorph in the MnP4 system, all of which are stacking variants of nets built with manganese and phosphorus atoms. In γ-MnP4, there are two Mn-Mn distances (2.93 and 3.72 Å) arising from a Peierls-like distortion effectively forming Mn2 dumbbells in the structure. Magnetic and electrical conductivity measurements show diamagnetism and a small anisotropic band gap (100-200 meV) with significantly enhanced conductivity along the crystallographic a axis. Calculations of the electronic and vibrational (phonon) structures show the P-P and Mn-P bonds within the nets are mainly responsible for the stability of the phase. The similar bonding motifs of the polymorphs give rise to the existence of numerous dynamically stable variants. The calculated Helmholtz energy shows the polymorph formation to be closely tied to temperature with the 6-MnP4 structure favorable at low temperatures, the 2-MnP4 favorable between approximately 800 and 2000 K, and 8-MnP4 preferred at high temperatures.

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Section: ■ Introductionmentioning

confidence: 97%

Section: ■ Introductionmentioning

confidence: 98%

Section: ■ Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

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Discovery of γ-MnP₄ and the Polymorphism of Manganese Tetraphosphide

et al. 2015

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First Row Transition Metal Phosphides

Whitmire

Caudell

2004

Encyclopedia of Inorganic and Bioinorganic Chemistry

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A review with 209 references of the binary and ternary metal phosphides for the first row transition metals. A large variety exists in M:P stoichiometry for this class of compounds although a number of general trends are easily identified. Compounds with different transition metals having the same M:P ratio often adopt similar crystallographic forms, providing tremendous flexibility in producing isostructural ternary or higher order compounds over a wide composition range. In some cases, however, a given M:P stoichiometry can choose to crystallize in one of two different crystal systems depending on transition metal, temperature, pressure, and dopant metals. Common features of the variety of structural types are presented. Crystal data are tabulated for compounds exhibiting a variety of different M:P stoichiometries for each transition metal in the first series. For ternary phosphides containing more than one first row transition metal, crystal data is also presented showing that these compounds adopt the structure of one of the parent metals involved. The metal phosphides have been well‐studied for the electronic, magnetic, and catalytic properties and a number of examples of these properties are presented.

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