A new tilt and an old twist on the nickel arsenide structure-type: synthesis and characterisation of the quaternary transition-metal cyanamides A2MnSn2(NCN)6 (A = Li and Na)

2019 ◽  
Vol 48 (40) ◽  
pp. 15029-15035 ◽  
Author(s):  
Alex J. Corkett ◽  
Richard Dronskowski
Keyword(s):  
Crystal Structure ◽  
Transition Metal ◽  
Structure Type ◽  
Type Synthesis

Two quaternary transition-metal cyanamides with a novel crystal structure are stabilised through cyanamide tilts and octahedral twists.

Crystal chemistry of transition metal diarsenates M 2As2O7 (M = Mn, Co, Ni, Zn): variants of the thortveitite structure

2010 ◽  
Vol 66 (6) ◽  
pp. 603-614 ◽  
Author(s):  
Matthias Weil ◽  
Berthold Stöger
Keyword(s):  
Crystal Structure ◽  
Low Temperature ◽  
Transition Metal ◽  
Basic Structure ◽  
Structure Type ◽  
Ambient Conditions ◽  
Modulated Structure ◽  
Triclinic Crystal System ◽  
Space Groups ◽  
Unit Cells

The structures of the 3d divalent transition-metal diarsenates M 2As2O7 (M = Mn, Co, Ni, Zn) can be considered as variants of the monoclinic (C2/m) thortveitite [Sc2Si2O7] structure type with a ≃ 6.7, b ≃ 8.5, c ≃ 4.7 Å, α ≃ 90, β ≃ 102, γ ≃ 90° and Z = 2. Co2As2O7 and Ni2As2O7 are dimorphic. Their high-temperature (β) polymorphs adopt the thortveitite aristotype structure in C2/m, whereas their low-temperature (α) polymorphs are hettotypes and crystallize with larger unit cells in the triclinic crystal system in space groups P\bar 1 and P1, respectively. Mn2As2O7 undergoes no phase transition and likewise adopts the thortveitite structure type in C2/m. Zn2As2O7 has an incommensurately modulated crystal structure [C2/m(α,0,γ)0s] with q = [0.3190 (1), 0, 0.3717 (1)] at ambient conditions and transforms reversibly to a commensurately modulated structure with Z = 12 (I2/c) below 273 K. The Zn phase resembles the structures and phase transitions of Cr2P2O7. Besides descriptions of the low-temperature Co2As2O7, Ni2As2O7 and Zn2As2O7 structures as five-, three- and sixfold superstructures of the thortveitite-type basic structure, the superspace approach can also be applied to descriptions of all the commensurate structures. In addition to the ternary M 2As2O7 phases, the quaternary phase (Ni,Co)2As2O7 was prepared and structurally characterized. In contrast to the previously published crystal structure of the mineral petewilliamsite, which has the same idealized formula and has been described as a 15-fold superstructure of the thortveitite-type basic structure in space group C2, synthetic (Ni,Co)2As2O7 can be considered as a solid solution adopting the α-Ni2As2O7 structure type. Differences of the two structure models for (Ni,Co)2As2O7 are discussed.

The crystal chemistry of (Mn3 +, Fe3+)-substituted andalusites (viridines and kanonaite), (Al1−x−yMn3x+Fe3y+)2 (OǀSiO4): crystal structure refinements, Mössbauer, and polarized optical absorption spectra

1981 ◽  
Vol 155 (1-2) ◽  
Author(s):  
I. Abs-Wurmbach ◽  
K. Langer ◽  
F. Seifert ◽  
E. Tillmanns
Keyword(s):  
Crystal Structure ◽  
Transition Metal ◽  
Optical Absorption ◽  
Metal Ions ◽  
Crystal Chemistry ◽  
Mixed Crystal ◽  
Transition Metal Ions ◽  
Structure Type ◽  
Optical Absorption Spectra ◽  
Distorted Octahedral

AbstractThe crystal chemistry of viridines and kanonaite, (AlThe structure refinements reveal that the transition metal ions substitute for Al almost exclusively in the distorted octahedral Al(l) site of the andalusite structure type within the entire mixed crystal series. This is independently proven by the Mössbauer results for

Synthese und Kristallstruktur von Pt2Sn2Zn3, der ersten ternären Verbindung im System Pt/Sn/Zn / Synthesis and Crystal Structure of Pt2Sn2Zn3, the First Ternary Compound of the Pt/Sn/Zn System

2006 ◽  
Vol 61 (7) ◽  
pp. 862-866 ◽  
Author(s):  
Rainer Lux ◽  
Harald Hillebrecht
Keyword(s):  
Crystal Structure ◽  
Transition Metal ◽  
Single Crystals ◽  
Ternary Compound ◽  
Structure Type ◽  
Synthesis And Crystal Structure ◽  
Binary Compounds

Single crystals of Pt2Sn2Zn3, the first ternary compound in the system Pt/Sn/Zn, have been synthesised from the elements. Pt2Sn2Zn3 exhibits a new structure type (hP14, P63/mmc, Z = 2, a = 4.3367(5), c = 15.532(3) Å , 402 reflections, 14 variables, R1(F) = 0.025, wR2(I) = 0.059) with motifs of the binary compounds. One Pt atom has a cubic environment (PtSn6Zn2), the second one forms an Edshammer polyhedron (PtSn2Zn9). Pt2Sn2Zn3 is one of the few examples of a ternary Sn/Zn compound of a transition metal.

The Crystal Structure of NbO2I – A Double-layer Structure with 7-Coordinated Niobium

2007 ◽  
Vol 62 (12) ◽  
pp. 1543-1548 ◽  
Author(s):  
Sabina Hartwig ◽  
Harald Hillebrecht
Keyword(s):  
Crystal Structure ◽  
Transition Metal ◽  
Single Crystals ◽  
Structure Determination ◽  
Layer Structure ◽  
Chemical Transport ◽  
Structure Type ◽  
Van Der Waals Interactions ◽  
Double Layers ◽  
Double Layer Structure

Single crystals of NbO2I were obtained as dark red needles by chemical transport. According to the structure determination (Pnma, a = 20.897(4), b = 3.7654(8), c = 3.9715(8) Å , Z = 4, 619 reflections, 26 variables, R1(F) = 0.0645, wR2(F2) = 0.1597) NbO2I represents a new structure type with 7- coordinated Nb atoms. Pentagonal bipyramids NbO5I2 are connected via the apical O atoms with alternating short and long Nb-O distances (1.79 / 2.20 Å ) to chains and via the three equatorial O atoms to double layers. Between the double layers there are only weak van-der-Waals interactions of the I atoms. NbO2I is the first oxide halide of a transition metal with CN 7. Structurally NbO2I is closely related to UO2Br, but with alternating short and long Nb-O distances as a difference.

Ln3Cu4P4O2: a New Lanthanide Transition Metal Pnictide Oxide Structure Type

1996 ◽  
Vol 453 ◽  
Author(s):  
R. J. Cava ◽  
H. W. Zandbergen ◽  
J. J. Krajewski ◽  
T. Siegrist ◽  
H. Y. Hwang ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Transition Metal ◽  
Homologous Series ◽  
Structure Type ◽  
Magnetic Susceptibilities ◽  
Oxide Structure ◽  
Trivalent Lanthanides ◽  
New Type

AbstractA new type of lanthanide transition metal pnictide-oxide, Ln3Cu4P4O2 (for Ln = La, Ce, and Nd), is reported. The crystal structure is made from Ln2O2 layers of the Pb2O2 type stacked with layers of Cu2P2 tetrahedra. The existence of a homologous series of compounds with similar chemistry connecting the BiCuOSe and ThCr2Si2 structure types is indicated. The resistivity of La3Cu4P4O2 is metallic, with no superconductivity observed above 2K. The Ce and Nd compounds have magnetic susceptibilities characteristic of the trivalent Lanthanides. The Ce compound orders magnetically at approximately 0.8 K.

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