Structure Refinement of the S-Phase Precipitate MgCuAl2

2005 ◽  
Vol 60 (5) ◽  
pp. 491-494 ◽  
Author(s):  
Birgit Heying ◽  
Rolf-Dieter Hoffmann ◽  
Rainer Pöttgen
Keyword(s):  
Single Crystal ◽  
Original Work ◽  
Induction Furnace ◽  
Structure Refinement ◽  
S Phase ◽  
Crystal Chemical ◽  
X Ray Diffraction ◽  
Variable Parameters ◽  
X Ray ◽  
Phase Precipitate

The technologically important S-phase precipitate MgCuAl2 has been synthesized from the elements in a sealed tantalum tube in an induction furnace. The aluminide was investigated by powder and single crystal X-ray diffraction methods: Cmcm, a = 401.19(9), b = 926.5(2), c = 712.4(1) pm, wR2 = 0.0425, 234 F2 values, and 16 variable parameters. The new crystallographic data fully confirm the original work by Perlitz and Westgren [Ark. Kemi, Mineral. Geol. 16, 1 (1943)], but the present structure refinement has led to a much higher precision. The crystal chemical peculiarities of MgCuAl2 are briefly discussed.

Structure Refinement of BaIrIn2

2005 ◽  
Vol 60 (1) ◽  
pp. 118-120 ◽  
Author(s):  
Jan F. Riecken ◽  
Rainer Pöttgen
Keyword(s):  
Single Crystal ◽  
Induction Furnace ◽  
Structure Refinement ◽  
Two Dimensional ◽  
Moisture Sensitivity ◽  
Variable Parameters ◽  
X Ray ◽  
Coordination Numbers

BaIrIn2 was synthesized from the elements in a sealed tantalum tube in an induction furnace. The indide was investigated by powder and single crystal X-ray data: Cmcm, a = 443.3(1), b = 1151.3(2), c = 806.0(1) pm, wR2 = 0.0471, 352 F2 values, and 16 variable parameters. The iridium and indium atoms build up two-dimensional [IrIn2]2− polyanions (279 - 281 pm Ir-In and 310-314 pm In-In) which are separated and charge-balanced by the barium atoms. The two-dimensional character of the polyanion is responsible for the strong moisture sensitivity of BaIrIn2. The coordination numbers for barium, iridium, and indium are 15, 9, and 12, respectively.

Ternary Antimonides RE4T7Sb6 (RE=Gd–Lu; T =Ru, Rh) with Cubic U4Re7Si6-type Structure

2013 ◽  
Vol 68 (9) ◽  
pp. 971-978 ◽  
Author(s):  
Inga Schellenberg ◽  
Ute Ch. Rodewald ◽  
Christian Schwickert ◽  
Matthias Eul ◽  
Rainer Pöttgen
Keyword(s):  
Magnetic Susceptibility ◽  
Single Crystal ◽  
Magnetic Moment ◽  
Induction Furnace ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
X Ray ◽  
Antiferromagnetic Ordering ◽  
Arc Melting ◽  
Intermediate Valent

The ternary antimonides RE4T7Sb6 (RE=Gd-Lu; T =Ru, Rh) have been synthesized from the elements by arc-melting and subsequent annealing in an induction furnace. The samples have been characterized by powder X-ray diffraction. Four structures were refined on the basis of single-crystal X-ray diffractometer data: U4Re7Si6 type, space group Im3m with a=862.9(2) pm, wR2=0.0296, 163 F2 values for Er4Ru7Sb6; a=864.1(1) pm, wR2=0.1423, 153 F2 values for Yb4Ru7Sb6; a=872.0(2) pm, wR2=0.0427, 172 F2 values for Tb4Rh7Sb6; and a=868.0(2) pm, wR2=0.0529, 154 F2 values for Er4Rh7Sb6, with 10 variables per refinement. The structures have T1@Sb6 octahedra and slightly distorted RE@T26Sb6 cuboctahedra as building units. The distorted cuboctahedra are condensed via all trapezoidal faces, and this network leaves octahedral voids for the T1 atoms. The ruthenium-based series of compounds was studied by temperature-dependent magnetic susceptibility measurements. Lu4Ru7Sb6 is Pauli-paramagnetic. The antimonides RE4Ru7Sb6 with RE=Dy, Ho, Er, and Tm show Curie-Weiss paramagnetism. Antiferromagnetic ordering occurs at 10.0(5), 5.1(5) and 4.0(5) K for Dy4Ru7Sb6, Ho4Ru7Sb6 and Er4Ru7Sb6, respectively, while Tm4Ru7Sb6 remains paramagnetic. Yb4Ru7Sb6 is an intermediate-valent compound with a reduced magnetic moment of 3.71(1) μB per Yb as compared to 4.54 μB for a free Yb3+ ion

Structure refinement of (Al, Zn)49Mg32-type phases by single-crystal X-ray diffraction

2000 ◽  
Vol 294-296 ◽  
pp. 327-330 ◽  
Author(s):  
W. Sun ◽  
F.J. Lincoln ◽  
K. Sugiyama ◽  
K. Hiraga
Keyword(s):  
Single Crystal ◽  
Structure Refinement ◽  
X Ray Diffraction ◽  
X Ray

scholarly journals Redetermination of Sr2PdO3 from single-crystal X-ray data

2019 ◽  
Vol 75 (1) ◽  
pp. 30-32
Author(s):  
Gohil S. Thakur ◽  
Hans Reuter ◽  
Claudia Felser ◽  
Martin Jansen
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Diffraction Data ◽  
Structure Refinement ◽  
Structure Type ◽  
X Ray Diffraction ◽  
High Quality ◽  
X Ray ◽  
Cell Parameters ◽  
Anisotropic Displacement Parameters

The crystal structure redetermination of Sr2PdO3 (distrontium palladium trioxide) was carried out using high-quality single-crystal X-ray data. The Sr2PdO3 structure has been described previously in at least three reports [Wasel-Nielen & Hoppe (1970). Z. Anorg. Allg. Chem. 375, 209–213; Muller & Roy (1971). Adv. Chem. Ser. 98, 28–38; Nagata et al. (2002). J. Alloys Compd. 346, 50–56], all based on powder X-ray diffraction data. The current structure refinement of Sr2PdO3, as compared to previous powder data refinements, leads to more precise cell parameters and fractional coordinates, together with anisotropic displacement parameters for all sites. The compound is confirmed to have the orthorhombic Sr2CuO3 structure type (space group Immm) as reported previously. The structure consists of infinite chains of corner-sharing PdO4 plaquettes interspersed by SrII atoms. A brief comparison of Sr2PdO3 with the related K2NiF4 structure type is given.

Structure Refinement of CePtSi and Hydrogenation Behavior of CePdGe, CePtSi and CePtGe

2007 ◽  
Vol 62 (4) ◽  
pp. 613-616 ◽  
Author(s):  
Wilfried Hermes ◽  
Ute Ch. Rodewald ◽  
Bernard Chevalier ◽  
Rainer Pötgena
Keyword(s):  
Single Crystal ◽  
Diffraction Data ◽  
Structure Refinement ◽  
Three Dimensional ◽  
Subsequent Annealing ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hydride Formation ◽  
Arc Melting ◽  
Cerium Compounds

The intermetallic cerium compounds CePdGe, CePtSi, and CePtGe were synthesized from the elements by arc-melting and subsequent annealing. The structure of CePtSi was refined from single crystal X-ray diffraction data: LaPtSi-type (ordered α-ThSi2 version), 141md, a = 419.6(1) and c = 1450.0(5) pm, wR2 = 0.0490, 362 F2 values and 16 variables. The Pt-Si distances within the three-dimensional [PtSi] network are 242 pm, indicating strong Pt-Si interactions. Hydrogenation of the three compounds at 623 K and 4 MPa H2 gave no indication for hydride formation.

Al analogue of chayesite from a lamproite of Cancarix, SE Spain, and its crystal structure

2020 ◽  
Vol 196 (3) ◽  
pp. 193-198
Author(s):  
Natalia V. Zubkova ◽  
Nikita V. Chukanov ◽  
Christof Schäfer ◽  
Konstantin V. Van ◽  
Igor V. Pekov ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Diffraction Data ◽  
Empirical Formula ◽  
Structure Refinement ◽  
Crystal Chemical ◽  
Chemical Formula ◽  
Crystal Chemical Formula ◽  
X Ray Diffraction ◽  
Se Spain ◽  
X Ray

Al analogue of chayesite (with Al > Fe3+) was found in a lamproite from Cancarix, SE Spain. The mineral forms green thick-tabular crystals up to 0.4 mm across in cavities. The empirical formula derived from EMP measurements and calculated on the basis of 17 Mg + Fe + Al + Si apfu is (K0.75 Na0.20 Ca0.11)Mg3.04 Fe0.99 Al1.18 Si11.80 O30. The crystal structure was determined from single crystal X-ray diffraction data ( R = 2.38%). The mineral is hexagonal, space group P 6/ mcc, a = 10.09199(12), c = 14.35079(19) Å, V = 1265.78(3) Å3, Z = 2. Fe is predominantly divalent. Al is mainly distributed between the octahedral A site and the tetrahedral T 2 site. The crystal chemical formula derived from the structure refinement is C (K0.73 Na0.16 Ca0.11)B (Na0.02)4 A(Mg0.42 Al0.29 Fe0.29)2 T 2(Mg0.71 Fe0.16 Al0.13)3 T 1(Si0.985 Al0.015)12 O30.

Single-crystal X-ray diffraction, EMPA, FTIR and X-ray photoelectron spectroscopy study of narsarsukite from Murun Massif, Russia

2017 ◽  
Vol 81 (2) ◽  
pp. 339-354 ◽  
Author(s):  
E. Schingaro ◽  
E. Mesto ◽  
M. Lacalamita ◽  
F. Scordari ◽  
E. Kaneva ◽  
...  
Keyword(s):  
Single Crystal ◽  
Photoelectron Spectroscopy ◽  
Chemical Study ◽  
Structural Disorder ◽  
Crystal Chemical ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Alkaline Massif

AbstractA crystal chemical study of narsarsukite from the Murun alkaline massif, Russia has been carried out combining single-crystal X-ray diffraction, electron microprobe analyses, micro-Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The narsarsukite single crystals are tetragonal (space group I4/m) with unit-cell parameters: 10.7140(1) ≤ a ≤ 10.7183(2) Å and 7.9478(1) ≤ c ≤ 7.9511(1) Å. The XPS analysis showed that Fe occurs in the mineral as Fe3+, whereas the FTIR spectrum showed that the sample studied is anhydrous. The average crystal chemical formula of the Murun narsarsukite is: Na2.04K0.01(V0.015+Ti0.74Zr0.01Al0.01Fe0.223+Mg0.01)1.00Si4.00(O10.74F0.23OH0.03)11.00. Structural disorder at octahedral and interstitial sites was modelled and also discussed in consideration of the main substitutional mechanism Ti4+ + O2– ↔ Fe3+ + (F–, OH–) active in the structure of the mineral.

Copper-rich Intermetallic Compounds RECu9Cd2(RE = La, Ce, Pr, Nd) with YNi9In2-type Structure

2012 ◽  
Vol 67 (11) ◽  
pp. 1225-1228 ◽  
Author(s):  
Michael Johnscher ◽  
Rainer Pöttgen
Keyword(s):  
Single Crystal ◽  
Intermetallic Compounds ◽  
Induction Furnace ◽  
Three Dimensional ◽  
Pair Formation ◽  
Type Structure ◽  
X Ray Diffraction ◽  
X Ray

The YNi9In2-type copper-rich compounds RECu9Cd2 (RE=La, Ce, Pr, Nd) were synthesized directly from the elements in sealed niobium ampoules in an induction furnace and were characterized by powder X-ray diffraction. The structure of PrCu9Cd2 was refined from single-crystal Xray diffractometer data: P4/mbm, a=849.0(3), c=498.2(3) pm, wR2=0.0418, 374 F2 values, 23 variables. The structure has two striking polyhedral motifs: Pr@Cu16Cd4 and Cu2@Cu8Cd4. The packing of these polyhedra describes the whole structure. The copper and cadmium atoms build up a three-dimensional [Cu9Cd2] network with broader ranges of Cu-Cu (246 - 274 pm) and Cu-Cd (272 - 288 pm) distances. The cadmium atoms show segregation through pair formation with Cd-Cd distances of 288 pm.

A single-crystal neutron and X-ray diffraction study of a Li, Be-bearing brittle mica

2014 ◽  
Vol 78 (1) ◽  
pp. 55-72 ◽  
Author(s):  
G. D. Gatta ◽  
G. Nénert ◽  
G. Guastella ◽  
P. Lotti ◽  
A. Guastoni ◽  
...  
Keyword(s):  
Chemical Analysis ◽  
Single Crystal ◽  
Scattering Length ◽  
Structure Refinement ◽  
Site Occupancy ◽  
Emission Spectrometry ◽  
X Ray Diffraction ◽  
Plasma Atomic Emission Spectrometry ◽  
X Ray ◽  
Final Population

AbstractThe crystal chemistry of a meso-octahedral Li,Be-bearing mica from the Harding pegmatite (Dixon, Taos County, New Mexico, USA) has been investigated by constant-wavelength single-crystal neutron diffraction at 20 K, single-crystal X-ray diffraction at 100 K and inductively coupled plasma-atomic emission spectrometry (ICP-AES). The chemical composition based on ICP-AES analysis leads to the following chemical formula (calculated on the basis of 12 oxygen atoms):Ca(Na0.26K0.04Ca0.69)∑0.99M(Li0.29Mg0.03Fe0.023+Al1.78)∑2.12T(Al1.73Be0.16Si2.11)S4.00O12H2.53. The apparent excess of H is probably due to the fact that the fraction of H2O was assumed by difference to 100 wt.%, and slightly overestimated. On the basis of the previous experimental findings on Li,Be-bearing mica, X-ray (at 100 K) and neutron (at 20 K) structure refinements were performed in the space groupsCcandC2/c. The neutron structure refinement in the space groupCcoffers a view about the (Al,Be,Si)-tetrahedral ordering: the best fit of the refinement was reached with theT1 andT4 sites occupied by (Be + Al) andT2 andT3 fully occupied by Si. This leads to a final population ofT(Al1.88Be0.12Si2.00)∑4.00p.f.u., in reasonable agreement with the chemical analysis. The neutron refinement provides unambigous evidence of the occurrence of Li at theM1 site. The refined fraction of Li at theM1 site ranges between 0.27 and 0.29 a.p.f.u., in excellent agreement with the chemical analysis. The presence of Li, at least at a significant level, at theM2 (andM3) site can be ruled out, as a full site occupancy with the scattering length of Al was obtained. The location of the H sites and the complex hydrogen-bonding scheme are described. A comparison between the structure features of this Li,Be-mica and other brittle micas is carried out.

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