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The Samson phase, β-Mg2Al3, revisited

The Al-Mg phase diagram has been reinvestigated in the vicinity of the stability range of the Samson phase, β-Mg2Al3 (cF1168). For the composition Mg38.5Al61.5, this cubic phase, space group Fd3̄m (no 227), a = 28.242(1) Å, V = 22526(2) Å3, undergoes at 214°C a first-order phase transition to rhombohedral β′-Mg2Al3, (hR293), a = 19.968(1) Å, c = 48.9114(8) Å, V = 16889(2) Å3, (i.e. 22519 Å3 for th

Low-temperature structural transitions in the phonon-glass thermoelectric material β-Zn 4 Sb 3 : Ordering of Zn interstitials and defects

The low-temperature phase transitions of thermoelectric Zr 4 Sb 3 have been characterized using singlecrystal X-ray diffraction, electrical resistance, and thermal conductivity measurements. Room-temperature stable, disordered β-Zn 4 Sb 3 undergoes a phase transition at 254 K to ordered α-n 4 Sb 3 , which has an ideal composition Zn 4 Sb 10 . Below 235 K, a second low-temperature phase (α′-Zn

Synthesis, crystal structure, phase relations and chemical bonding analysis of the new Nowotny chimney-ladder compound ZrBi1.62

ZrBi1.62 is a new compound crystallising with an incommensurate Nowotny chimney-ladder structure, which was refined from single crystal X-ray diffraction data using a four-dimensional formalism. The tetragonal unit cell has the lattice parameters a = 6.958 (7) Å, c = 3.460 (3) Å and q = (0 0 0.382). The symmetry is described by the superspace group pair W:P4/nnc:q-1q1-P:I41/amd:1-1ss. The full pha

Lone-pair interfaces that divide inorganic materials into ionic and covalent parts

The lone (ar)ranger: The structure of Cu20Sb35O 44Cl37 is divided up into two parts: ionically bonded Cu+-Cl- supertetrahedra (green) and covalently bonded clusters that resemble zeolite β cages. The Sb3+ ions (gray) lie at the vertices of the cages, while their lone pairs of electrons form surfaces that separate the covalent and ionic parts. (Figure Presented).

Complexity of hexagonal approximates in the RE13Zn ∼58 system (RE = Ce, Pr, Nd, Sm, Gd, Tb and Dy)

For the RE13Zn58 quasicrystal approximants (RE = Ce, Pr, Nd, Sm, Gd, Tb, Dy), single crystals were prepared from the elements and their structures were refined from single-crystal X-ray diffraction data. They are derived from the Gd13Cd58 type structure and crystallize in the space group P63/mmc or its subgroups. The crystal structures of Ce and Pr compounds are identical to that of the archetype,

Structural study of the disordered RECd6 quasicrystal approximants (RE = Tb, Ho, Er, Tm and Lu)

The crystal structures of approximants RECd6 (RE = Tb, Ho, Er, Tm and Lu) have been refined from single crystal X-ray diffraction data. This work is a continuation of a previous study of MCdg approximants [1] in which the different types of disorder of the central Cd4 tetrahedra located in the dodecahedral cavities were examined. The structures of the title compounds are all similar to GdCd6 and d

The structure of onoratoite, Sb8 O11 X2 (X = Cl, Br) revisited

The crystal structure of Sb8O11Cl2 (onoratoite) is redetermined in the triclinic space group P-1. The crystal structure was previously described by a partially disordered model in the monoclinic space group C 2 / m containing some partially occupied oxygen atoms. The new structural model features exclusively atomic positions that are fully occupied. The crystal structure was solved from single cry

Structure and bonding properties of (Bi2Se3)m(Bi2)n stacks by first-principles density functional theory

We have investigated crystal structure, chemical bonding, and electronic properties of the compounds Bi2Se3, BiSe, Bi4Se3, and Bi2Se by first-principles calculations within the density functional theory. The compounds are members of a general series of stacks (Bi2Se3)m(Bi2)n composed of five-layer blocks Se-Bi-Se-Bi-Se and two-layer blocks Bi-Bi. Both types of blocks can be considered as closed-sh

The crystal structure of CuSb2O3Br : Slabs from cubic Sb2O3 interspersed between puckered hexagonal CuBr-type layers

The new compound CuSb2O3Br crystallize in the monoclinic space group Cc. The unit cell parameters are a=7.9189(15)Å, b=13.7105(10)Å, c=19.048(2)Å, β=90°, Z=16. The crystal structure is solved from single crystal data, R=0.0490. The compound show a layered structure with slabs from cubic Sb2O3 interspersed in between puckered layers of CuBr. The Sb(III) atoms have tetrahedral [SbO3E] coordination w

Inheritance of the guanidinium chloride structure in two molybdenum (II) chloride salts

Depending on the proticity of the solvent, two different salts may be crystallized from the combination of solutions of guanidinium chloride, C(NH2)3Cl, and the acidic hydrate of molybdenum dichloride, [(Mo6Cl8)Cl6](H20 O9). From aprotic solvents such as dimethyl sulfoxide (DMSO) or formamide (FA), compound I, [(Mo6Cl8) Cl6]Cl6(C(NH2)3)8, crystallizes, while from protic solvents such as ethanol or

Highly hydrated cations : Deficiency, mobility, and coordination of water in crystalline nonahydrated scandium(III), yttrium(III), and lanthanoid(III) trifluoromethanesulfonates

Trivalent lanthanide-like metal ions coordinate nine water oxygen atoms, which form a tricapped trigonal prism in a large number of crystalline hydrates. Water deficiency, randomly distributed over the capping positions, was found for the smallest metal ions in the isomorphous nonahydrated trifluoromethanesulfonates, [M-(H2O)n](CF 3SO3)3, in which M = ScIII, Lu III, YbIII, TmIII or ErIII. The hydr

Synthesis and study of Sr-substituted misfit layer sulfides

Two series of [(Ln1/3Sr2/3S)1.15] 1.15NbS2 (1.5Q/1H) and (Ln1- Sr S) 1+ NbS2 (1Q/1H) misfit layer sulfides have been synthesised and studied by X-ray powder and single crystal diffraction, EDX-analysis and magnetic measurements. For the early lanthanides (Ln = La, Ce) only the (Ln1- Sr S)1+ NbS2 (< 0.40-0.45, = 0.15-0.17) compounds were formed whereas for late lanthanides (Ln = Pr, Nd, Sm, Gd-Er,

Host-guest compounds in the family of tellurium-nickel oxohalogenides

The peeling of an onion: Embedded in the voids of an infinite cationic [Te32Ni30X3O90]5+ network lies an icosahedral [Ni4X13]5- anionic guest cluster (ochre). It may be considered wrapped and trapped in a successive series of concentric skins made from the lone pairs of Te atoms (blue), the Te (yellow), O (red), and Ni atoms (light blue polyhedra). But are there any other guests?

New Sr-substituted niobium-based misfit layer sulfides

Two series of [(Ln1/3Sr2/3S)1.5]1.15NbS2and (Ln1-xSrxS)1+yNbS2misfit layer sulfides have been synthesized and studied by X-ray powder and single crystal diffraction, electron diffraction, and EDX-analysis. The [(Sm1/3Sr2/3S)1.5]1. 15NbS2compound belongs to the 1.5Q/1H homologue type where the Sr-cations are mainly located at the exterior of the Q-slab whereas Sm preferably occupy the positions at

Phase stability in the systems AeAl2-xMgx (Ae = Ca, Sr, Ba) : Electron concentration and size controlled variations on the laves phase structural theme

The systems AeAl2-xMgx (Ae = Ca, Sr, Ba) display electron concentration induced Laves phase structural changes. However, the complete sequence MgCu2 → MgNi2 → MgZn 2 with increasing x (decreasing electron count) is only observed for Ae = Ca. Compounds SrAl2-xMgx (0 < x ≤ 2) and BaAl2-xMgx (x = 0.85 and 2.0) were synthesized and structurally characterized by X-ray diffraction experiments. For the S

Superstructure of Eu4Cd25 : A quasicrystal approximant

The quasicrystal approximant Eu4Cd25, formerly designated EuCd6, was synthesized and characterized by means of single-crystal X-ray diffraction. Superstructure reflections corresponding to an F-centered cubic unit cell with a doubled cell-parameter relative to the I-centered cubic sub-cell could be observed in the diffraction data. This gives the largest cubic unit cell reported to date among bina

The incommensurably modulated structure of ζ-Zn3-xSb 2

The incommensurately modulated structure of ζ-Zn3-xSb 2 was solved and refined versus X-ray single crystal diffraction data using a 3+1 dimensional superspace formalism. The compound crystallizes in the orthorhombic system in the 3+1 dimensional superspace group Pnna(α0)0s0 with the cell parameters a=7.283(3)Å, b=15.398(5)Å, c=25.06(1)Å, q=(α,0,0), α≈0.385. The structure features columns of interg

The structures of X2[(Mo6Cl8)Cl 6]·nH2O, X=NH4, K, Rb, Cs

The title compounds were synthesized from MoCl2 and the appropriate commercial chlorides and their structures were solved by a combination of single crystal X-ray diffraction analysis and theoretical methods. The NH4, K and Rb compounds are essentially isostructural, and crystallize in space group Ia (No. 9) with the cell parameters (in Å) a=9.173(1), b=14.986(2), c=17.505(3), β=92.94(2)°(NH4); a=

Site occupancy wave and charge density wave in the modulated structure of Nd0.6Gd0.4Se1.85

Single crystals of Nd0.6Gd0.4Se1.85 have been prepared by chemical transport reactions starting from pre-annealed powder samples. Satellite reflections observed in X-ray and electron diffraction experiments indicate the presence of a two-dimensional lattice distortion. The origin of this is a site occupancy wave and, coupled to this, a charge density wave in the planar selenium layer of this compo