Reexamination of the crystal structure of semseyite, Pb9Sb8S21

2018 ◽  
Vol 233 (3-4) ◽  
pp. 279-284 ◽  
Author(s):  
Yoshitaka Matsushita
Keyword(s):  
Crystal Structure ◽  
Chemical Composition ◽  
Single Crystal ◽  
Structure Refinement ◽  
Unit Cell ◽  
Crystal Structure Refinement ◽  
Cell Level ◽  
Single Crystal Specimen ◽  
Cation Sites ◽  
Occupancy Behavior

AbstractThe crystal structure of semseyite, Pb9Sb8S21was successfully refined using a single-crystal specimen from Wolfsberg, Harz, Germany, having chemical composition (EPMA) Pb9.01(1)Sb8.00(3)S21.05(5). The structure belongs to the monoclinicC2/cspace group (a=13.6267(10) Å,b=11.9742(9) Å,c=24.5891(18) Å,β=105.997(3)°,V=3856.8(5) Å3,Z=4,Dc=6.048 g/cm3). Crystal structure refinement with all atoms refined anisotropically converged toR1=4.64% (I>2σ(I)). The crystal structure is built of two subunits (A and B) showing TlSbS2-like topology. Each of them stacks parallel to (001), andc/2 in thickness. Two cation sites (Pb1 and Sb5) located at central part of the subunit, show mixed occupancy behavior as 95% Pb and 5% Sb at the Pb5 site, and 95% Sb and 5% Pb at the Sb1 site, respectively. Each of subunits are related by unit cell-level twinning mechanism “tropochemical cell twinning” with the TlSbS2-like subunits alternatively parallel to (1 1 −4) and (−1 1 4) planes.

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

Crystal and powder XRD data of Mg3(PO4)2-III: High-temperature and high-pressure form

1995 ◽  
Vol 10 (4) ◽  
pp. 293-295 ◽  
Author(s):  
F. Brunet ◽  
C. Chopin ◽  
A. Elfakir ◽  
M. Quarton
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
High Temperature ◽  
Single Crystal ◽  
Diffraction Pattern ◽  
Structure Refinement ◽  
Powder Xrd ◽  
Single Crystal Structure ◽  
Crystal Structure Refinement ◽  
Pressure Form

A new diffraction pattern of the high-temperature and high-pressure polymorph Mg3(PO4)2-III (PDF 43-500) is given and indexed on the basis of a single-crystal structure refinement. It allows diffractogram indexing of the isostructural high-temperature and high-pressure form of Co3(PO4)2 (PDF 43-499).

Protoenstatite: a crystal-structure refinement at 1100°C

1971 ◽  
Vol 134 (3-4) ◽  
Author(s):  
Joseph R. Smyth
Keyword(s):  
Crystal Structure ◽  
Melting Point ◽  
Single Crystal ◽  
Structure Refinement ◽  
Three Dimensional ◽  
Intensity Data ◽  
Crystal Structure Refinement ◽  
Space Group

AbstractTechniques allowing single-crystal investigations on the precession camera up to the melting point of platinum have been developed. The crystal structure of protoenstatite has been refined from three-dimensional intensity data obtained at 1100°C using a crystal of enstatite from the Norton County, Kansas meteorite. The space group is

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.

Single-crystal structure refinement of enargite [Cu3AsS4]

1994 ◽  
Vol 29 (11) ◽  
pp. 1121-1127 ◽  
Author(s):  
J.A. Henao ◽  
G. Díaz de Delgado ◽  
J.M. Delgado ◽  
F.J. Castrillo ◽  
O. Odreman
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Structure Refinement ◽  
Single Crystal Structure ◽  
Crystal Structure Refinement
Sign in / Sign up

Export Citation Format

Share Document