Synthesis, crystal structures and properties of the new compounds K7–x Ag1+x (XO4)4 (X = Mo, W)

2017 ◽  
Vol 73 (12) ◽  
pp. 1071-1077 ◽  
Author(s):  
Tatyana S. Spiridonova ◽  
Sergey F. Solodovnikov ◽  
Aleksandra A. Savina ◽  
Zoya A. Solodovnikova ◽  
Sergey Yu. Stefanovich ◽  
...  
Keyword(s):  
Second Harmonic ◽  
Analysis Data ◽  
Rietveld Analysis ◽  
Structure Type ◽  
Polar Space ◽  
Scanning Calorimetry ◽  
Cell Dimensions ◽  
Unit Cell Dimensions ◽  
First Order Phase ◽  
New Compounds

Two new isostructural compounds, namely heptapotassium silver tetrakis(tetraoxomolybdate), K7–x Ag1+x (MoO4)4 (0 ≤ x ≤ 0.4), and heptapotassium silver tetrakis(tetraoxotungstate), K7–x Ag1+x (WO4)4 (0 ≤ x ≤ 0.4), have been synthesized and found to crystallize in the polar space group P63 mc (Z = 2) with the unit-cell dimensions a = 12.4188 (2) and c = 7.4338 (2) Å for K6.68Ag1.32(MoO4)4 (single-crystal data), and a = 12.4912 (5) and c = 7.4526 (3) Å for K7Ag(WO4)4 (Rietveld analysis data). Both structures represent a new structure type, with characteristic [K1(XO4)6] `pinwheels' of K1O6 octahedra and six XO4 tetrahedra (X = Mo, W) connected by common opposite faces into columns along the c axes. The octahedral columns are linked to each other through Ag1O4 tetrahedra along with the K2 and K3/Ag2 polyhedra, forming the polar rods (...Ag1O4–X1O4–empty octahedron–Ag1O4...). Ag1 is located almost at the centre of the largest face of its coordination tetrahedron and seems to have some mobility. The new structure type is related to the Ba6Nd2Al4O15 and CaBaSiO4 types, and to other structures of the α-K2SO4–glaserite family. The differential scanning calorimetry (DSC) and second harmonic generation (SHG) results show that both compounds undergo first-order phase transformations to high-temperature centrosymmetric phases.

Structure and Phase Transition of [(CH2OH)3CNH3]2SiF6

2003 ◽  
Vol 58 (2-3) ◽  
pp. 121-125 ◽  
Author(s):  
B. Kosturek ◽  
Z. Czapla ◽  
A. Waskowska
Keyword(s):  
Phase Transition ◽  
Optical Observations ◽  
Linear Birefringence ◽  
Temperature Phase ◽  
Scanning Calorimetry ◽  
Dsc Measurements ◽  
First Order Phase Transition ◽  
Cell Dimensions ◽  
Unit Cell Dimensions ◽  
First Order Phase

Single crystals of (TRIS)2SiF6 were grown and characterised by X-ray analysis, differential scanning calorimetry (DSC) and optical investigations. They were bond to be trigonal, space group P3̅, with the unit cell dimensions a = 7.699(1), c = 7.818(2) Å . The SiF2-6 anions, located in large cavities formed by hydrogen bonded cations, are strongly disordered at room temperature. The DSC measurements revealed a first-order phase transition at TC ≈ 177 K with a hysteresis of 4 K. The nature of the transition was confirmed by a sharp increase of the linear birefringence below TC. Optical observations under a polarizing microscope showed a domain structure of the low temperature phase, characteristic of ferroelastic materials

A synchrotron study of bladder urolith architecture

2000 ◽  
Vol 15 (2) ◽  
pp. 94-100
Author(s):  
K. D. Rogers ◽  
M. W. Sperrin ◽  
E. J. MacLean
Keyword(s):  
Calcium Oxalate ◽  
Calcium Oxalate Monohydrate ◽  
Rietveld Analysis ◽  
Calcium Oxalate Dihydrate ◽  
New Approach ◽  
Surface Data ◽  
Cell Dimensions ◽  
Crystalline Nature ◽  
Unit Cell Dimensions

The principal aim of this study was to assess a new approach to the characterization of uroliths using synchrotron radiation. To achieve this, a detailed investigation of the crystalline nature of a human bladder urolith has been undertaken. Changes in the phase composition and crystalline mineral nature have been measured from the urolith core center to its outer surface. Data were collected using a microbeam, synchrotron probe, and image plate. Rietveld analysis has enabled us to determine that the unit cell dimensions of the majority phases (anhydrous uric acid and calcium oxalate monohydrate) are significantly greater in the core region but become progressively smaller from the outer to inner regions. The crystallites of both phases are also shown to possess significant radial orientation which varies through the urolith and reaches a maximum at a point of principal fracture. The analysis has also allowed us to study the change in average crystallite morphology; the crystallites of both phases are shown to decrease in size toward the outer parts of the urolith although this is in a nonuniform fashion. Evidence of calcium oxalate dihydrate was also found, but only within the outermost region of the urolith.

Rietveld analysis of high-density polyethylene

1994 ◽  
Vol 9 (3) ◽  
pp. 217-220 ◽  
Author(s):  
Sampath S. Iyengar ◽  
Simona Percec
Keyword(s):  
Crystallite Size ◽  
High Density Polyethylene ◽  
Internal Standard ◽  
Rietveld Analysis ◽  
Unit Cell ◽  
High Density ◽  
Cell Dimensions ◽  
Oriented Films ◽  
Degree Of Orientation ◽  
Unit Cell Dimensions

Wide angle X-ray powder diffraction data from unoriented and uniaxially oriented films of high-density polyethylene were analyzed by the Rietveld whole pattern profile fitting technique. A Voigt function was used to model the profile and extract crystallographic information such as the unit cell dimensions, crystallite size and strain, and degree of orientation. The analysis revealed that the technique was efficient in providing not only accurate unit cell dimensions without an internal standard, but also crystallite size and strain information. The oriented films were also successfully modeled with this technique.

Crystal structure of a synthetic aluminoan tantalian titanite: a reconnaissance study

2006 ◽  
Vol 70 (1) ◽  
pp. 115-121 ◽  
Author(s):  
R. P. Liferovich ◽  
R. H. Mitchell
Keyword(s):  
Crystal Structure ◽  
Structural Data ◽  
Rietveld Analysis ◽  
Synthetic Analogue ◽  
X Ray Diffraction ◽  
Coordination Polyhedra ◽  
X Ray ◽  
Ceramic Synthesis ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

AbstractA synthetic analogue, Ca(Ti0.6Al0.2Ta0.16Nb0.04)OSiO4, of an aluminoan tantalian titanite previously described from Craveggia pegmatite (Piemonte, Italy) has been prepared by a ceramic synthesis technique and its crystal structure determined by Rietveld analysis of the powder X-ray diffraction pattern. The synthetic Al-Ta-Nb-rich titanite adopts space group A2/a implying that substitutions at the single octahedral site destroy the coherence of the off-centering of octahedral chains in the titanite structure resulting in a P21/a → A2/a phase transition. Unit-cell dimensions obtained for the Al-Ta-Nb-rich titanite are: a = 7.0649(1) Å; b = 8.7187(1) Å; c = 6.5701(1) Å; β = 113.755(1)°, V = 370.41(1) Å3. The extensive replacement of Ti by Al, Ta and Nb results in a considerable decrease in the distortion of all coordination polyhedra in the structure of this titanite. These structural data suggest that a solid solution CaTi1-x(Alx/2 [Ta,Nb]x/2)OSiO4 (0 ≤ x ≤ 0.4) adopting the titanite structure might exist.

Crystal structure determination of new compounds Li6MB3O9 (M=Nd,Sm,Eu,Tm,Er)

2008 ◽  
Vol 23 (1) ◽  
pp. 3-9 ◽  
Author(s):  
Y. F. Lou ◽  
W. Y. Wang ◽  
G. M. Cai ◽  
Y. P. Sun ◽  
C. Wang
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Diffraction Analysis ◽  
Crystal Structure Analysis ◽  
X Ray Diffraction ◽  
Space Group ◽  
Cell Dimensions ◽  
Unit Cell Dimensions ◽  
New Compounds

New compounds Li6MB3O9 (M=Nd,Sm,Eu,Tm,Er) were synthesized by solid-state reaction. The crystal structure of Li6NdB3O9 was analyzed from both powder and single crystal X-ray diffraction data. The results obtained by powder diffraction analysis and Rietveld refinement are a=7.2725(4) Å, b=16.6398(9) Å, c=6.7529(5) Å, β=105.398(8)°, and space group P21/c, which agree with the results obtained by single crystal diffraction analysis: a=7.2712(4) Å, b=16.6268(9) Å, c=6.7484(4) Å, β=105.411(1)°, and space group P21/c. This compound is isostructural with Li6YB3O9. Single crystal structure analysis showed that the fundamental building unit of these isostructural compounds comprises three isolated [BO3]3− triangles, one distorted [NdO8]13− triangulated dodecahedron, four distorted [LiO5]9− five-coordinated polyhedra, and two [LiO4]7− tetrahedron. An analysis of the infrared spectrum of Li6NdB3O9 confirmed the presence of isolated [BO3]3− triangles in Li6NdB3O9. The remaining four Li6MB3O9 (M=Nd, Sm, Eu, Tm, and Er) compounds were found to be isostructural with Li6NdB3O9. Their unit cell dimensions decrease with an increase in the atomic number of the rare-earth atoms. DTA and TGA measurements of Li6MB3O9 (M=Nd, Sm, Eu, Tm, and Er) revealed that these borates congruently melt from 800 °C to 860 °C.

Notizen: Über neue ternäre Fluoride vom Typ Ag3MF3, und AgMF4 / On New Ternary Fluorides of the Type Ag3MF6 and AgMF4

1979 ◽  
Vol 34 (12) ◽  
pp. 1765-1766 ◽  
Author(s):  
Roland Lösch ◽  
Christoph Hebecker
Keyword(s):  
Structure Type ◽  
Unit Cell ◽  
Cell Dimensions ◽  
Unknown Structure ◽  
Unit Cell Dimensions

Unit cell dimensions of new Ag3MF6 com­pounds have been determined by Guinier-photographs: Ag3AlF6 and Ag3GaF6 crystallize tetragonally (isostructurally to Rb3TlFe); Ag3ScF6, Ag3lnFe and Ag3TlF6 are monoclinic (Na3AlF6- type). AgGaF4 crystallizes tetragonally (iso­structurally to KFeF4), AgScF4 monoclinic in a new, unknown structure type.

scholarly journals Crystal structure and phase transition in the compound [C6H17N3]TlCl5.2H2O

2016 ◽  
Vol 8 (1) ◽  
pp. 1508-1522
Author(s):  
Hiba Khili ◽  
Najla Chaari ◽  
Abdelaziz Koumina ◽  
Slaheddine Chaabouni
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Differential Scanning Calorimetry ◽  
Dielectric Constant ◽  
Impedance Spectroscopy ◽  
Dissipation Factor ◽  
Scanning Calorimetry ◽  
Monoclinic System ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

The title compound 1-(2-ammonium-ethyl) piperaziniumpentachlorothallate (III) dihydrate crystallizes in the monoclinic system with space group Cm. The unit cell dimensions are: a = 12.786(5), b = 12.021(5), c = 10.566(5) Å, β = 93.469(5) °, with Z = 4. Its crystal structure was determined and refined down to R = 0.045. The structure of this compound consists of 1-(2-ammonium-éthyl) pipéraziniumcations and [Tl2Cl10]4- dimers. The arylammoniumcations are located between anions and connected to the halogen atoms by N-H…Cl hydrogen bonds. One phase transition at T = 320 K is detected and studied by differential scanning calorimetry, dielectric and impedance spectroscopy measurements. The evolution of the dielectric constant and dissipation factor as a function of temperature revealed the transition characterized by a strong jump in the conductivity plot. 

scholarly journals Minerology of Nipe Clay

1969 ◽  
Vol 76 (3-4) ◽  
pp. 107-117
Author(s):  
Miguel A. Muñoz ◽  
Jerry M. Bigham
Keyword(s):  
Surface Area ◽  
Clay Fraction ◽  
High Capacity ◽  
Unit Cell ◽  
Bet Surface Area ◽  
Scanning Calorimetry ◽  
Ir Radiation ◽  
Mole Percent ◽  
Cell Dimensions ◽  
Unit Cell Dimensions

The mineralogy of Nipe clay was characterized by means of X-ray diffraction (XRD), differential scanning calorimetry (DSC), infrared spectroscopy (FTIR), BET surface area, and chemical analysts. The major components of the clay fraction are goethite, gibbsite, hematite and kaolinite. Goethite is the predominant iron oxide as indicated by the high intensity of the XRD peaks. The unit cell dimensions of goethite, estimated from the XRD data, were a = 4.603 Å, b = 9.806 Å and c = 3.002 Å. The unit cell dimensions of hematite were a = 5.037 Å, and c = 13.735 Å. The extent of aluminum substitution in goethite and hematite was also estimated from the XRD data. The mole % Al in goethite, based on the d (111) value, was 15.57 mole percent, whereas when the a-dimension of the unit cell was used, a value of 12.86 mole percent was obtained. The estimated mole percent Al substitution in hematite was 0.67. The hematite/goethite ratio as estimated from the relative intensities of the 104 peak of hematite and the 110 peak of goethite was 0.51. Kaolinite showed a high capacity to absorb IR radiation as indicated by strong absorption peaks around 1000 and 3700 cm-1. The surface area of the clay as determined by the BET method was 55.26 m2/g. The ratio of Feox/Fed was very low (1.17x10-2), indicating that the iron oxides occur in well crystallized form.

The External Shape of Human γ GI Immunoglobulin from Crystal Sections

1971 ◽  
Vol 29 ◽  
pp. 428-429
Author(s):  
L. W. Labaw
Keyword(s):  
Molecular Weight ◽  
Sodium Phosphate ◽  
Osmium Tetroxide ◽  
Unit Cell ◽  
Monoclinic Space Group ◽  
X Ray ◽  
Large Molecular Weight ◽  
Cell Dimensions ◽  
Unit Cell Dimensions ◽  
Crystallographic Axes

Crystals of a human γGl immunoglobulin have the external morphology of diamond shaped prisms. X-ray studies have shown them to be monoclinic, space group C2, with 2 molecules per unit cell. The unit cell dimensions are a = 194.1, b = 91.7, c = 51.6Å, 8 = 102°. The relatively large molecular weight of 151,000 and these unit cell dimensions made this a promising crystal to study in the EM.Crystals similar to those used in the x-ray studies were fixed at 5°C for three weeks in a solution of mother liquor containing 5 x 10-5M sodium phosphate, pH 7.0, and 0.03% glutaraldehyde. They were postfixed with 1% osmium tetroxide for 15 min. and embedded in Maraglas the usual way. Sections were cut perpendicular to the three crystallographic axes. Such a section cut with its plane perpendicular to the z direction is shown in Fig. 1.This projection of the crystal in the z direction shows periodicities in at least four different directions but these are only seen clearly by sighting obliquely along the micrograph.

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