scholarly journals Determination of the Local Crystal-Chemical Features of Complex Chalcogenides by Copper, Antimony, and Arsenic NQR

10.5772/46939 ◽  
2010 ◽  
Author(s):  
R.R. Gainov ◽  
A.V. Dooglav ◽  
I.N. Penkov ◽  
A.Yu. Orlova ◽  
I.A. Evlampiev ◽  
...  
Keyword(s):  
Crystal Chemical

Nondestructive determination of the amphibole crystal‐chemical formulae by Raman spectroscopy: One step closer

2019 ◽  
Vol 51 (9) ◽  
pp. 1530-1548 ◽  
Author(s):  
Naemi Waeselmann ◽  
Jochen Schlüter ◽  
Thomas Malcherek ◽  
Giancarlo Della Ventura ◽  
Roberta Oberti ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Crystal Chemical ◽  
Nondestructive Determination ◽  
One Step ◽  
Amphibole Crystal

Weissite from Gambatesa mine, Val Graveglia, Liguria, Italy: occurrence, composition and determination of the crystal structure

2013 ◽  
Vol 77 (4) ◽  
pp. 475-483 ◽  
Author(s):  
L. Bindi ◽  
C. Carbone ◽  
D. Belmonte ◽  
R. Cabella ◽  
R. Bracco
Keyword(s):  
Crystal Structure ◽  
Vickers Hardness ◽  
Crystal Chemical ◽  
Chemical Formula ◽  
Unit Cell Parameters ◽  
Cell Parameters ◽  
Black Streak ◽  
Pure Metals ◽  
Complex Crystal

AbstractWeissite, Cu2–xTe (x ≈ 0.21), a very rare copper telluride, occurs in a sample from the Gambatesa mine, Val Graveglia, Liguria, Italy, where it occurs as purplish black anhedral grains up to 0.1 mm in length and shows a black streak. No cleavage is observed and the Vickers hardness (VHN100) is 142 kg/mm2. Weissite is dark bluish black, weakly pleochroic, and moderately anisotropic in bluish tints. Reflectance percentages in air for Rmin and Rmax are 37.0, 38.4 (471.1 nm), 33.2, 34.2 (548.3 nm), 31.2, 32.1 (586.6 nm), and 28.6, 31.0 (652.3 nm), respectively.Weissite is trigonal and belongs to the space group P3m1 with the following unit-cell parameters: a = 8.3124(7) Å, c = 21.546(1) Å, V = 1289.3(2) Å3, and Z = 24. Electron microprobe analyses gave the chemical formula (Cu1.62Ag0.04Au0.04Fe0.04Sb0.04)Σ=1.78(Te0.96S0.02Se0.02). The crystal structure has been solved and refined to R = 1.95%. It consists of Cu and Te polyhedra forming complex crystal-chemical environments as is typical of many intermetallic compounds. The exceedingly short bond distances observed among the metals are discussed in relation to other copper tellurides and pure metals.

Crystal-Chemical Approach to the Determination of Oxo-Centered Complexes in Divalent Lead Silicates

2021 ◽  
Vol 66 (1) ◽  
pp. 43-55
Author(s):  
T. A. Eremina ◽  
E. L. Belokoneva ◽  
N. N. Eremin ◽  
E. I. Marchenko
Keyword(s):  
Crystal Chemical ◽  
Chemical Approach

Structure determination of KScS2, RbScS2and KLnS2(Ln = Nd, Sm, Tb, Dy, Ho, Er, Tm and Yb) and crystal–chemical discussion

2015 ◽  
Vol 71 (7) ◽  
pp. 623-630 ◽  
Author(s):  
Lubomír Havlák ◽  
Jan Fábry ◽  
Margarida Henriques ◽  
Michal Dušek
Keyword(s):  
Rare Earth ◽  
Structure Determination ◽  
Structure Type ◽  
Trivalent Cation ◽  
Crystal Chemical ◽  
Ionic Radii ◽  
Structural Family ◽  
Trivalent Cations ◽  
Ytterbium Sulfide

The title structures of KScS2(potassium scandium sulfide), RbScS2(rubidium scandium sulfide) and KLnS2[Ln = Nd (potassium neodymium sufide), Sm (potassium samarium sulfide), Tb (potassium terbium sulfide), Dy (potassium dysprosium sulfide), Ho (potassium holmium sulfide), Er (potassium erbium sulfide), Tm (potassium thulium sulfide) and Yb (potassium ytterbium sulfide)] are either newly determined (KScS2, RbScS2and KTbS2) or redetermined. All of them belong to the α-NaFeO2structure type in agreement with the ratio of the ionic radiir3+/r+. KScS2, the member of this structural family with the smallest trivalent cation, is an extreme representative of these structures with rare earth trivalent cations. The title structures are compared with isostructural alkali rare earth sulfides in plots showing the dependence of several relevant parameters on the trivalent cation crystal radius; the parameters thus compared arec,aandc/a, the thicknesses of the S—S layers which contain the respective constituent cations, the sulfur fractional coordinatesz(S2−) and the bond-valence sums.

scholarly journals New structural data reveal benleonardite to be a member of the pearceite-polybasite group

2015 ◽  
Vol 79 (5) ◽  
pp. 1213-1221 ◽  
Author(s):  
Luca Bindi ◽  
Christopher J. Stanley ◽  
Paul G. Spry
Keyword(s):  
Scientific Literature ◽  
Silver Ions ◽  
Structural Data ◽  
Crystal Chemical ◽  
Dimensional Diffusion ◽  
Group A ◽  
Diffusion Paths ◽  
Using Data ◽  
Linear Coordination

AbstractThe determination of the crystal structure of benleonardite (P3m1; R = 0.0321 for 1250 reflections and 102 parameters; refined formula Ag15.00Cu1.00Sb1.58As0.42S7.03Te3.97) obtained using data from a gem-quality, untwinned crystal recovered from the type material, revealed that benleonardite exhibits the structure observed for minerals of the pearceite-polybasite group. The structure consists of the stacking of [Ag6(Sb,As)2S6Te]2– A and [Ag9Cu(S,Te)2Te2]2+B layer modules in which (Sb, As) forms isolated SbS3 pyramids typically occurring in sulfosalts; Cu links two (S,Te) atoms with linear coordination, and Ag occupies sites with coordination geometries ranging from quasi-linear to almost triangular. The silver ions are found in the B layer module along two-dimensional diffusion paths and their electron densities are evidenced by means of a combination of a Gram-Charlier development of the atom displacement factors and a split model. In the structure, two S positions are completely replaced by Te (i.e. Te3 and Te4) and one is half occupied [S1: S0.514(9)Te0.486], whereas S2 is completely filled by sulfur. This distribution reflects the crystal-chemical environments of the different cations. On the basis of information gained from this characterization, the crystal-chemical formula of benleonardite was revised according to the structural results, yielding Ag15Cu(Sb,As)2S7Te4 (Z = 1) instead of Ag8(Sb,As)Te2S3(Z = 2) as previously reported. Thus, the mineral must be considered a member of the pearceite-polybasite group. A recalculation of the chemical data listed in the scientific literature for benleonardite according to the structural results obtained here leads to excellent agreement.

Structure determination of KLaS2, KPrS2, KEuS2, KGdS2, KLuS2, KYS2, RbYS2, NaLaS2and crystal-chemical analysis of the group 1 and thallium(I) rare-earth sulfide series

2014 ◽  
Vol 70 (2) ◽  
pp. 360-371 ◽  
Author(s):  
Jan Fábry ◽  
Lubomír Havlák ◽  
Michal Dušek ◽  
Přemysl Vaněk ◽  
Jan Drahokoupil ◽  
...  
Keyword(s):  
Rare Earth ◽  
Chemical Analysis ◽  
Crystal Structures ◽  
Structural Type ◽  
Crystal Chemical ◽  
Crystal Chemical Analysis ◽  
Cell Parameters ◽  
Structure Determinations ◽  
Group 1

One of the purposes of this work is to provide a crystallographic review of group 1 and thallium rare-earth ternary sulfidesM+Ln3+S2. We have therefore determined crystal structures of KLaS2, KPrS2, KEuS2, KGdS2, KLuS2, KYS2, RbYS2, which belong to the α-NaFeO2structural family (R \bar 3 m), as well as NaLaS2, which is derived from the disordered NaCl structural type (Fm \bar 3 m). The determined structures were compared with known members of the group 1 as well as thallium(I) rare-earth sulfides by the standard tools of crystal-chemical analysis such as comparison of bond-valences, analysis of interatomic distances and comparison of the unit-cell parameters. The results indicate why the cubic structural type is limited to Li+and Na+members of the series only. The analysis has also revealed frequent problems in the reported crystal structures, especially in the determination of the K+compounds, probably due to severe absorption and different accuracy and sensitivity of various instruments. Intense diffuse scattering has been discovered in NaLaS2, which will be the subject of further investigation. The newly determined as well as already known structures are summarized, together with critical comments about possible errors in the previous structure determinations.

scholarly journals Synthesis and X-Ray Crystal Structure Determination of Thiotrithiazyl Iododichloride, S4N3ICl2

2002 ◽  
Vol 57 (12) ◽  
pp. 1387-1390 ◽  
Author(s):  
Stephan H. Irsen ◽  
Richard Dronskowski
Keyword(s):  
Crystal Structure ◽  
Rietveld Refinement ◽  
Structure Determination ◽  
Crystal Structure Determination ◽  
Crystal Chemical ◽  
Monoclinic System ◽  
X Ray

Thiotrithiazyl iododichloride, S4N3ICl2, has been synthesized from molecular S4N4 and liquid ICl and structurally characterized by an X-ray Rietveld refinement. S4N3ICl2 crystallizes in the monoclinic system (P21/c, a = 611.548(7), b = 877.336(8), c = 1770.12(2) pm, β = 92.3357(7)°, Z = 4), follows the crystal-chemical motif (S4N3+)(ClICl−), and is thus isotypic with (S4N3+ )(Br3− ). The crystal structure contains a planar S4N3+ ring and a linear ClICl− unit.

scholarly journals Ab initio constrained crystal-chemical Rietveld refinement of Ca10(V x P1 − x O4)6F2 apatites

2007 ◽  
Vol 63 (1) ◽  
pp. 37-48 ◽  
Author(s):  
Patrick H. J. Mercier ◽  
Zhili Dong ◽  
Thomas Baikie ◽  
Yvon Le Page ◽  
T. J. White ◽  
...  
Keyword(s):  
Ab Initio ◽  
Rietveld Refinement ◽  
Vanadium Content ◽  
Crystal Chemical ◽  
Initial Attempt ◽  
Rietveld Refinements ◽  
Space Groups ◽  
Uniform Expansion ◽  
Vanadium Ion

Extraction of reliable bond distances and angles for Ca10(V x P1 − x O4)6F2 apatites using standard Rietveld refinement with Cu Kα X-ray powder data was significantly impaired by large imprecision for the O-atom coordinates. An initial attempt to apply crystal-chemical Rietveld refinements to the same compounds was partly successful, and exposed the problematic determination of two oxygen–metal–oxygen angles. Ab initio modeling with VASP in space groups P63/m, P21/m and Pm showed that both these angular parameters exhibited a linear dependence with the vanadium content. Stable crystal-chemical Rietveld refinements in agreement with quantum results were obtained by fixing these angles at the values from ab initio simulations. Residuals were comparable with the less precise standard refinements. The larger vanadium ion is accommodated primarily by uniform expansion and rotation of BO4 tetrahedra combined with a rotation of the Ca–Ca–Ca triangular units. It is proposed that the reduction of symmetry for the vanadium end-member is necessary to avoid considerable departures from formal valences at the A II and B sites in P63/m. The complementarity of quantum methods and structural analysis by powder diffraction in cases with problematic least-squares extraction of the crystal chemistry is discussed.

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