Notizen: Single-Crystal Structure Refinement of LiZnAs

1993 ◽  
Vol 48 (5) ◽  
pp. 683-684 ◽  
Author(s):  
Wolfgang Hönle
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Structure Refinement ◽  
Single Crystal Structure ◽  
Crystal Structure Refinement ◽  
X Ray ◽  
Zinc Blende ◽  
Ray Methods

The crystal structure of LiZnAs has been verified with single crystal X-ray methods. LiZnAs crystallizes in a filled-up zinc blende type of structure (F 43 m, a = 593.9(1) pm, As at site 4a (000); Zn at site 4d (3/4 3/4 3/4); Li at site 4 c (1/4 1/4 1/4); 25 hkl; R = 0.018). As is coordinated by 4 Li and 4 Zn atoms with identical distances of 257.2(1) pm. Li and Zn atoms are tetrahedrally coordinated by As. No indications for a disorder between Li and Zn have been found.

scholarly journals Recommended X-ray single-crystal structure refinement and Rietveld refinement procedure for tremolite

2021 ◽  
Vol 77 (4) ◽  
Author(s):  
Paolo Ballirano ◽  
Beatrice Celata ◽  
Alessandro Pacella ◽  
Ferdinando Bosi
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Rietveld Refinement ◽  
Structure Refinement ◽  
Point Of View ◽  
Single Crystal Structure ◽  
Crystal Structure Refinement ◽  
Statistical Point ◽  
X Ray ◽  
Refinement Procedure

A detailed description of the structure of the amphibole-supergroup minerals is very challenging owing to their complex chemical composition that renders the process of cation partition extremely difficult, particularly because of the occurrence of multivalent elements. Since amphiboles naturally occur under a fibrous morphology and have largely been used to produce asbestos, there is a growing demand for detailed and accurate structural data in order to study the relationships between structure, composition and toxicity. The present study proposes a recommended refinement procedure for both X-ray single-crystal structure refinement (SREF) and Rietveld analysis for tremolite, selected as a test case. The corresponding structural results are compared to estimate the `degree of confidence' of the Rietveld refinement with regard to SREF. In particular, it is shown that the interpretation of the electron density of the tremolite structure by SREF is model dependent. By assuming that the site-scattering values from SREF should be as close as possible to those from electron microprobe analysis, as a crucial constraint for the correct description of the final crystal-chemical model, it is found that it is best satisfied by using partially ionized scattering curves (SCs) for O and Si, and neutral SCs (neutral oxygen curves or NOCs) for other atoms. This combination leads to the best fit to the diffraction data. Moreover, it is found that Rietveld refinement using NOCs produces the best structural results, in excellent agreement with SREF. It is worth noting that, due to the complexity of the diffraction pattern and the fairly large number of freely refinable parameters, refinements with different combinations of SCs produce results almost indistinguishable from a statistical point of view, albeit showing significant differences from a structural point of view.

X-ray single-crystal structure refinement of the 129 K superconductor HgxPb1−xBa2Ca3Cu4O10+δ

1995 ◽  
Vol 243 (1-2) ◽  
pp. 10-18 ◽  
Author(s):  
H. Schwer ◽  
J. Karpinski ◽  
K. Conder ◽  
L. Lesne ◽  
C. Rossel ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Structure Refinement ◽  
Single Crystal Structure ◽  
Crystal Structure Refinement ◽  
X Ray

Neue Niob- und Tantalchloride der Zusammensetzung A4[M6Cl18] (A = (Ga,) In, TI; M = Nb, Ta) / New Niobium and Tantalum Chlorides of the Composition A4[M6Cl18] (A = (Ga,) In, TI; M = Nb, Ta)

1995 ◽  
Vol 50 (9) ◽  
pp. 1373-1376 ◽  
Author(s):  
Béla Baján ◽  
H.-Jürgen Meyer
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
General Formula ◽  
Coordination Sphere ◽  
Structure Refinement ◽  
Single Crystal Structure ◽  
Crystal Structure Refinement ◽  
Space Group ◽  
X Ray ◽  
New Compounds

AbstractThe syntheses of new compounds of the general formula A4[Nb6Cl18] (A = Ga, In, Tl) and A4[Ta6Cl18] (A = In, Tl) are reported. The indexing of their X-ray powder patterns was performed isotypically with K4Nb6Cl18]- A single-crystal structure refinement on In4[Ta6Cl18] gave the space group C2/m, Z - 2, a = 1077.7(3) pm, b = 1542.3(5) pm, c = 960.2(2) pm, β = 117.68(2) . The structure contains [Ta6Cl12Cl6]4- ions linked via I+ ions . In+ is situated in a strongly distorted coordination sphere of Cl- .

Iron in kornerupine; a57Fe Moessbauer spectroscopic study and comparison with single-crystal structure refinement

1999 ◽  
Vol 84 (4) ◽  
pp. 536-549 ◽  
Author(s):  
Edward S. Grew ◽  
Guenther J. Redhammer ◽  
Georg Amthauer ◽  
Mark A. Cooper ◽  
Frank C. Hawthorne ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Spectroscopic Study ◽  
Structure Refinement ◽  
Single Crystal Structure ◽  
Crystal Structure Refinement
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