Zur Hochdruckpolymorphie von Bal2 / High Pressure Polymorphism of Bal2

1981 ◽  
Vol 36 (10) ◽  
pp. 1255-1260 ◽  
Author(s):  
H. P. Beck
Keyword(s):  
High Pressure ◽  
Lattice Energy ◽  
Type Structure ◽  
Coordination Polyhedra ◽  
X Ray ◽  
Coordination Numbers ◽  
Bonding Type ◽  
P Type ◽  
Ray Methods

Abstract High pressure investigations of Bal2 yielded a new polymorph, which could be quenched and characterized by X-ray methods. PbCl2-type Bal2 is converted to an anti-Fe2P-type structure with more regular coordination polyhedra and an increase in effective coordination numbers. We discuss changes in bonding type by comparing the Madelung part of lattice energy in the two polymorphs.

Dimorphic ThNi2P2 with BaCu2S2 and CaBe2Ge2 Type Structure

1994 ◽  
Vol 49 (8) ◽  
pp. 1074-1080 ◽  
Author(s):  
Jörg H. Albering ◽  
Wolfgang Jeitschko
Keyword(s):  
Phase Transformation ◽  
High Temperature ◽  
Crystal Structures ◽  
Type Structure ◽  
Variable Parameters ◽  
Higher Symmetry ◽  
X Ray ◽  
Coordination Numbers ◽  
Structure Factors ◽  
High Temperature Form

Two modifications of ThNi2P2 were prepared in a tin flux at 850 °C (α-ThNi2P2) and 1000 °C (β-ThNi2P2). The crystal structures of both modifications were refined from single­crystal X-ray data. α-ThNi2P2 (BaCu2S2 type structure): Pnma. a = 819.69(5), b = 394.28(3), c = 981.54(7) pm. R = 0.028 for 32 variables and 654 structure factors: β-ThNi2P2 (CaBe2Ge2 type structure): P4/nmm, a = 408.5(1), c = 908.0(3) pm, R = 0.033 for 15 variable parameters and 261 F values. Although the two structures are closely related, they can be transformed into each other only by a reconstructive phase transformation. The differences and similari­ties of the two structures are discussed. The high temperature form has higher symmetry, a smaller number of variable positional parameters, and a tendency for higher coordination numbers.

scholarly journals Darstellung und Struktur ternärer Silizide und Germanide des Lithiums mit den Seltenen Erden Y und Gd im Fe2P-Typ / Preparation and Crystal Structure of Ternary Silicides and Germanides of Lithium with the Rare-Earth-Metals Y and Gd in the Fe2P-Type Structure

1979 ◽  
Vol 34 (8) ◽  
pp. 1057-1058 ◽  
Author(s):  
Axel Czybulka ◽  
Günter Steinberg ◽  
Hans-Uwe Schuster
Keyword(s):  
Crystal Structure ◽  
Rare Earth ◽  
Crystal Structures ◽  
Rare Earth Metals ◽  
Type Structure ◽  
Space Group ◽  
X Ray ◽  
P Type ◽  
Type Lattice ◽  
The Rare Earth

In the systems Li-M-X = (M = Y, Gd; X = Si, Ge) the compounds LiYSi, LiYGe and LiGdGe were prepared. Their crystal structures were determined by X-ray investigations. They crystallize hexagonally (space group P 6̄2m), and a C22-(Fe2P-type) lattice was found

scholarly journals MgNi2P - das erste ternäre Phosphid mit geordneter Fe3C-Struktur / MgNi2P - The First Ternary Phosphide with an Ordered Fe3C Type Structure

1994 ◽  
Vol 49 (8) ◽  
pp. 1071-1073 ◽  
Author(s):  
Viktor Keimes ◽  
Albrecht Mewis
Keyword(s):  
Single Crystal ◽  
Three Dimensional ◽  
Type Structure ◽  
X Ray ◽  
Ray Methods

MgNi2P was prepared by heating a mixture of the elements and investigated by means of single crystal X-ray methods. The compound crystallizes in an ordered Fe3C-type structure (Pnma; a = 6.477(1) Å, b = 6.364(1) Å, c = 5.001(1) Å; Z = 4). Ni and P atoms are linked together to a three-dimensional framework with octogonal tubes running along [010], which are occupied by Mg atoms in the form of stretched zigzag chains.

Ein Beitrag zur Chemie von Verbindungen des Bautyps MxPd3O4 / A Contribution to the Chemistry of the Compounds MxPd3O4

1979 ◽  
Vol 34 (12) ◽  
pp. 1661-1662 ◽  
Author(s):  
H.-J. Meyer ◽  
Hk. Müller-Buschbaum
Keyword(s):  
Single Crystals ◽  
Type Structure ◽  
Space Group ◽  
X Ray ◽  
Structure Space ◽  
Ray Methods

Single crystals of a new compound Pd0.5Pd3O4 were prepared and investigated by X-ray methods. It crystallizes with NaxPt3O4-type structure (space group Oh3-Pm3n, a = 575.6 pm). The distribution of the oxydation states of Pd with respect to the lattice positions is discussed.

Neue Chalcogenophosphate: KBaPS4, KBaPSe4 und Ba3PO4PSe4 / New Chalcogenophosphates: KBaPS4, KBaPSe4, and Ba3PO4PSe4

2005 ◽  
Vol 60 (4) ◽  
pp. 431-436 ◽  
Author(s):  
Stefan Jörgens ◽  
Albrecht Mewis
Keyword(s):  
Single Crystals ◽  
Type Structure ◽  
Coordination Polyhedra ◽  
Coordination Numbers ◽  
New Type ◽  
C 30 ◽  
Strong Distortion

Colourless single crystals of KBaPS4 (a = 11.587(2), b = 6.700(1), c = 10.118(2) Å ), and pale orange ones of KBaPSe4 (a = 11.972(2), b = 6.973(1), c = 10.388(2) Å ) were obtained by reactions of Ba3(PS4)2 and Ba3(PSe4)2, respectively, with KCl (790 °C; 30 h). The isotypic compounds crystallize with a slightly modified TlEuPS4 type structure (Pnma, Z = 4); that is, the characteristic units are distorted discrete PX4 tetrahedra (X: S, Se) interconnected by K+ and Ba2+. However, due to the strong distortion of the trigonal X6 prisms along [001] the coordination numbers increase from 8 to 9 for the barium atoms and from 8 to 11 for the potassium atoms. Orange crystals of Ba3PO4PSe4 (a= 6.779(1), b =7.108(1), c =12.727(3)Å ; α = 82.45(3)°, β =78.88(3)°, γ =81.34(3)°) resulted as a by-product of the synthesis of Ba3(PSe4)2. The compound crystallizes in a new type of structure (P1̅; Z = 2) and is the first chalcogenophosphate with discrete PO4 and PSe4 tetrahedra. The coordination polyhedra of the barium atoms are formed by both chalcogen atoms

AB2X2-Verbindungen im CaAl2Si2-Typ, V[1] Zur Struktur der Verbindungen CaMn2P2, CaMn2As2, SrMn2P2 und SrMn2As2 / AB2X2-Compounds with the CaAl2Si2 Structure, V [1] The Crystal Structure of CaMn2P2, CaMn2As2, SrMn2P2, and SrMn2As2

1978 ◽  
Vol 33 (6) ◽  
pp. 606-609 ◽  
Author(s):  
Albrecht Mewis
Keyword(s):  
Crystal Structure ◽  
Type Structure ◽  
Space Group ◽  
X Ray ◽  
Lattice Constants ◽  
Ternary Compounds ◽  
Structure Space ◽  
Ray Methods

Abstract Four ternary compounds with the formulas CaMn2P2, CaMn2As2, SrMn2P2, and SrMn2As2 have been prepared and investigated by X-ray methods. They are isotypic and crystallize trigonally in a CaAl2Si2-type structure (space group P3̅m 1-D33d) with the lattice constants: CaMn2P2 a = 4,096 ± 0,001 Å, c = 6,848 ± 0,002 Å, CaMn2As2 a = 4,239 ± 0,001 Å, c = 7,027 ± 0,003 Å, SrMn2P2 a = 4,168 ± 0,001 Å, c = 7,132 ± 0,001 Å, SrMn2As2 a = 4,306 ± 0,001 Å, c = 7,315 ± 0,001 Å. The lattice constants of BaMn2P2 and BaMn2As2 are given

Notizen:Neue Verbindungen mit CeNiSi2-Struktur / New Compounds with C eNiSi2-Type Structure

1996 ◽  
Vol 51 (8) ◽  
pp. 1213-1214 ◽  
Author(s):  
Dirk Johrendt ◽  
Christine Lux ◽  
Albrecht Mewis
Keyword(s):  
Type Structure ◽  
X Ray ◽  
New Compounds ◽  
Ray Methods

The compounds BaPdAs2 (a = 4.678(1), b = 17.330(2), c = 4.574(1) Å), BaPdSb2 (a = 4.877(1), b = 18.583(2), c = 4.889(1) Å) and BaPtAs2 (a = 4.660(1), b = 17.119(2), c = 4.608(1) Å) were prepared by heating mixtures of the elements and investigated by X-ray methods. They are isotypic and crystallize in the CeNiSi2-type structure (Cmcm), also called the BaCuSn2-type.

Eine Notiz über Li4[PbO4] [1, 2] / A Note on Li4[PbO4] [1,2]

1984 ◽  
Vol 39 (5) ◽  
pp. 566-576 ◽  
Author(s):  
Helmut Stoll ◽  
Rudolf Hoppe
Keyword(s):  
Crystal Structure ◽  
Lattice Energy ◽  
Coordination Polyhedra ◽  
Space Group ◽  
X Ray ◽  
Structure Description ◽  
Characteristic Features ◽  
Temperature Factors

The crystal structure of Li4PbO4 is reexamined by new X-ray data [Ag-Kα, four-circle-diffractometer CAD 4 (Enraf-Nonius), 863 of 890 Io, R = 1,88% and Rw = 1,79%, temperature factors of all particles ‘anisotropically’ refined, parameters see text]. Space group and parameters (see text) are confirmed, errors in the structure description [1] corrected. The characteristic features are shown using Extended Schlegel Diagrams of the coordination polyhedra. The Madelung Part of Lattice Energy, MAPLE, is calculated and discussed

scholarly journals NOTIZEN: Mg6Ni16As7 - eine neue G-Phase / Mg6Ni16As7 - a New G Phase

1995 ◽  
Vol 50 (8) ◽  
pp. 1275-1276 ◽  
Author(s):  
Viktor Keimes ◽  
Albrecht Mewis
Keyword(s):  
Single Crystal ◽  
Type Structure ◽  
X Ray ◽  
Ternary Compounds ◽  
Ray Methods

Mg6Ni16As7 (F m 3m ; a = 11.479(1) Å; Z = 4) was prepared by heating a mixture of the elements and investigated by means of single crystal X-ray methods. The arsenide crystallizes in a modified Th6Mn23 type structure, similar to many ternary compounds of the composition A6M16X7, called G phases.

Synthese und Kristallstrukturen von Seltenerdmetall-Antimoniden des Palladiums / Synthesis and Crystal Structures of Antimonides of Rare-Earth Metals and Palladium

2006 ◽  
Vol 61 (1) ◽  
pp. 17-22 ◽  
Author(s):  
Anette Imre ◽  
Albrecht Mewis
Keyword(s):  
Rare Earth ◽  
Rare Earth Metal ◽  
Three Dimensional ◽  
Earth Metal ◽  
Type Structure ◽  
X Ray ◽  
Metal Atoms ◽  
New Compounds ◽  
Ray Methods ◽  
The Rare Earth

The new compounds Pr3Pd6Sb5 (a = 13.442(3), b = 4.442(1), c = 9.994(2) Å ), Nd3Pd6Sb5 (a = 13.412(3), b = 4.431(1), c = 9.962(2) Å), and Gd3Pd6Sb5 (a = 13.293(2), b = 4.397(1), c = 9.881(2) Å) are isotypic and crystallize with the Ce3Pd6Sb5 type structure (Pmmn; Z = 2). The rare-earth metal atoms are arranged in form of three pseudo-body-centered subcells, whereas Pd and Sb atoms form a three-dimensional arrangement derived from the well-known ThCr2Si2 and CaBe2Ge2 structures. GdPdSb (a = 4.566(1), c = 7.444(1) Å) and DyPdSb (a = 4.545(1), c = 7.354(1) Å) crystallize with an ordered variant of the CaIn2 type structure (P63mc; Z = 2), also called as LiGaGe type, with slightly puckered hexagon nets of Pd and Sb atoms, which trigonally coordinate each other. In this series a decreasing radius of the rare-earth metal allows a tetrahedral non-metal environment of the Pd atoms and accordingly ScPdSb (a = 6.310(1) Å) forms the MgAgAs type structure (F4̄3m; Z = 4), a filled variant of the sphalerite type. The antimonides were prepared by heating mixtures of the elements at 600 °C and subsequent annealing at 900 - 1100 °C. Their structures have been determined by single-crystal X-ray methods.

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