New data for lansfordite

1982 ◽  
Vol 46 (341) ◽  
pp. 453-457 ◽  
Author(s):  
R. J. Hill ◽  
J. H. Canterford ◽  
F. J. Moyle
Keyword(s):  
Absorption Spectrum ◽  
Low Temperature ◽  
Diffraction Pattern ◽  
Powder Diffraction ◽  
Room Temperature ◽  
X Ray ◽  
Infra Red ◽  
Bicarbonate Solutions

AbstractEuhedral crystals of the low-temperature mineral lansfordite, MgCO3 · 5H2O, have been prepared from saturated magnesium bicarbonate solutions at temperatures below 10°C. The crystals are monoclinic P21/a with a = 12.4758(7), b = 7.6258(4), c = 7.3463(6)Å, β = 101.762(6)°, V = 684.24Å3, Dcalc. = 1.693 g cm−3, Dobs. = 1.70(1) g m−3. At room temperature, the crystals slowly effloresce to produce pseudomorphs of nesquehonite, MgCO3 · 3H2O. Dehydration is complete at 300°C, with decarbonation taking place in the interval to 560°C. A new X-ray powder diffraction pattern is presented, and details of the infra-red absorption spectrum are discussed.

Crystal structure of potassium tetraperoxomolybdate (VI) K2[Mo(O2)4]

2005 ◽  
Vol 20 (3) ◽  
pp. 203-206 ◽  
Author(s):  
M. Grzywa ◽  
M. Różycka ◽  
W. Łasocha
Keyword(s):  
Crystal Structure ◽  
Low Temperature ◽  
Diffraction Pattern ◽  
Powder Diffraction ◽  
Rietveld Method ◽  
Structure Refinement ◽  
Crystal Structure Refinement ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters

Potassium tetraperoxomolybdate (VI) K2[Mo(O2)4] was prepared, and its X-ray powder diffraction pattern was recorded at low temperature (258 K). The unit cell parameters were refined to a=10.7891(2) Å, α=64.925(3)°, space group R−3c (167), Z=6. The compound is isostructural with potassium tetraperoxotungstate (VI) K2[W(O2)4] (Stomberg, 1988). The sample of K2[Mo(O2)4] was characterized by analytical investigations, and the results of crystal structure refinement by Rietveld method are presented; final RP and RWP are 9.79% and 12.37%, respectively.

Structure of TlSr2PrCu207−x by Rietveld analysis

1994 ◽  
Vol 9 (3) ◽  
pp. 194-199
Author(s):  
Hoong-Kun Fun ◽  
Ping Yang ◽  
Rusli Othman ◽  
Tsong-Jen Lee ◽  
Chiou-Chu Lai ◽  
...  
Keyword(s):  
Low Temperature ◽  
Crystalline Structure ◽  
Powder Diffraction ◽  
Room Temperature ◽  
Goodness Of Fit ◽  
Rietveld Analysis ◽  
Crystal Data ◽  
X Ray ◽  
Tetragonal System

The crystalline structure of new TlSr2PrCu207−x was obtained at room temperature (300 K) and low temperature (100 K) from X-ray powder diffraction with CuKα radiation using Rietveld analysis. TlSr2PrCu207−x has an isotypical structure with TlBa2CaCu207 (1212). At 300 K, crystal data: Tl0.864Sr2PrCu2O6.75, Mr=727.811, the tetragonal system, P4/mmm, a =3.85404(5) Å, c = 12.1046(2) Å, V=179.80 Å3, Z=1, Dx =6.7218 g cm−3, μ =1143.922 cm−1 (λ = 1.54051 Å), F(000)=317.0, the structure was refined with 28 parameters to Rwp=5.29%, Rp = 3.65% for 3551 step intensities and Rb=7.40%, Rf=639% for 155 peaks, “goodness of fit” 5=3.05. At 100 K, crystal data: Tl0.858Sr2PrCu2O6.61, Mr=724.345, the tetragonal system, P4/mmm, a =3.84872(6) Å, c = 12.0771(3) Å, V=178.89 Å3, Z=1, Dx=6.7235 g cm−3, μ=1146.939 cm−1 (λ= 1.54051 Å), F(000) = 315.4, the structure was refined with 26 parameters to Rwp=6.70%, Rp=5.11% for 2926 step intensities and Rb=7.83%, Rf=6.70% for 131 peaks, “goodness of fit” S = 1.75.

Crystallization of anorthite from CaO–Al2O3–SiO2glasses

1970 ◽  
Vol 37 (291) ◽  
pp. 780-789 ◽  
Author(s):  
M. S. Y. Bhatty ◽  
J. A. Gard ◽  
F. P. Glasser
Keyword(s):  
Electron Diffraction ◽  
Low Temperature ◽  
Diffraction Pattern ◽  
Powder Diffraction ◽  
Powder Pattern ◽  
Molar Ratio ◽  
Measurable Effect ◽  
Apparent Absence ◽  
X Ray ◽  
Unique Manner

SummaryThe X-ray powder diffraction pattern of synthetic anorthite crystallized from a CaO-Al2O3-SiO2glass having the anorthite (1:1:2) molar ratio is identical with that reported in the literature, and also with that of a natural Japanese anorthite specimen. Increasing the CaO or SiO2content of the parent glasses used for crystallization studies has no measurable effect on that portion of the powder pattern attributable to anorthite. However, glasses containing an excess of Al2O3ranging from 5 to 10 mol % gave, after crystallization at temperatures belowc.1150 °C distinctively different powder pattern. Several powder reflections that are normally strong, such as, etc., were found to be virtually absent. Moreover, the chemical excess of Al2O3did not appear as a separate alumina-bearing phase. Upon reheating these anorthites to temperatures above 1200–50 °C or upon crystallizing a fresh portion of alumina-rich glass above 1200-50 °C, only the normal anorthite powder X-ray pattern was obtained; the pattern also contained some reflections due to corundum (α-Al2O3). Examination of the anomalous low-temperature anorthite by electron diffraction shows that the apparent absence of some powder lines is caused by both albite and Carlsbad twinning, which occur on an intimate scale not exceeding a few unit cell repeats. From the unique manner of its occurrence, the twinning is believed to be associated with the inclusion of an excess of Al3+in the anorthite.

X-ray powder diffraction study on ErNi2Ge2

1999 ◽  
Vol 14 (2) ◽  
pp. 145-146
Author(s):  
Liangqin Nong ◽  
Lingmin Zeng
Keyword(s):  
Least Squares ◽  
Diffraction Study ◽  
Diffraction Pattern ◽  
Powder Diffraction ◽  
Room Temperature ◽  
Rietveld Analysis ◽  
Lattice Parameters ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray

An X-ray diffraction pattern for ErNi2Ge2 at room temperature is reported. ErNi2Ge2 is tetragonal with lattice parameters a=4.0191(2) Å, c=9.7643(2) Å, space group I4/mmm, and Z=2. The lattice parameters derived from Rietveld analysis agree well with the results of a least-squares refinement.

X-ray powder diffraction data and structural study of Cd4GeSe6

1998 ◽  
Vol 13 (4) ◽  
pp. 202-209 ◽  
Author(s):  
J. A. Henao ◽  
J. M. Delgado ◽  
M. Quintero
Keyword(s):  
Crystal Structure ◽  
Diffraction Pattern ◽  
Powder Diffraction ◽  
Room Temperature ◽  
Rietveld Method ◽  
Monoclinic Space Group ◽  
Temperature Phase ◽  
Powder Diffraction Data ◽  
X Ray ◽  
Semiconducting Material

The X-ray powder diffraction pattern of the room temperature phase of Cd4GeSe6, a II4 □ IV VI6 semiconducting material, has been recorded and evaluated. This material crystallizes in the monoclinic space group Cc [No. 9] with a=12.847(3), b=7.407(2), c=12.854(2) Å, β=109.82(1)°, and Z=4. The powder diffraction pattern was also used to refine the crystal structure of this material employing the Rietveld method. The refinement of 56 parameters led to RWP=13.2%, RP=9.95% for 3751 step intensities and RB=7.05% and RF=5.20% for 833 reflections. Cd4GeSe6 can be considered a defect “adamantane-structure” material with a sphalerite-related superstructure.

X-ray powder diffraction data for ammonium D-gluconate, C6H11O7−NH4+

2003 ◽  
Vol 18 (2) ◽  
pp. 162-164
Author(s):  
F. J. W. J. Labuschagné ◽  
S. M. C. Verryn ◽  
W. W. Focke
Keyword(s):  
Diffraction Pattern ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Room Temperature ◽  
Powder Diffraction Data ◽  
X Ray ◽  
Cell Data

The compound ammonium D-gluconate (C6H11O7−NH4+) has been studied by X-ray powder diffraction. The powder diffraction pattern and data obtained at room temperature are presented (cell data and powder data summary).

X-ray powder diffraction data and structural study of Fe2GeSe4

1998 ◽  
Vol 13 (4) ◽  
pp. 196-201 ◽  
Author(s):  
J. A. Henao ◽  
J. M. Delgado ◽  
M. Quintero
Keyword(s):  
Diffraction Pattern ◽  
Structural Study ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Room Temperature ◽  
Rietveld Method ◽  
Structure Refinement ◽  
Powder Diffraction Data ◽  
Space Group ◽  
X Ray

The room temperature X-ray powder diffraction pattern of Fe2GeSe4, a II2 □ IV VI4 semiconducting compound, has been recorded and evaluated. This material was found to be orthorhombic, a=13.069(1), b=7.559(1), c=6.2037(6) Å, V=612.83(9) Å3, Z=4, Dx=5.42 gcm−3. The structure refinement carried out using the Rietveld method indicated that this material crystallizes in space group Pnma (No. 62) with an olivine type of structure. The refinement of 33 parameters led to RWP=15.3%, RP=10.2% for 5251 step intensities and RB=9.44% and RF=9.36% for 913 reflections.

A compact, transportable, thermoelectrically cooled cold stage for reflection geometry X-ray powder diffraction

2012 ◽  
Vol 45 (3) ◽  
pp. 608-610 ◽  
Author(s):  
Ian G. Wood ◽  
N. J. Hughes ◽  
F. Browning ◽  
A. D. Fortes
Keyword(s):  
Low Temperature ◽  
Powder Diffraction ◽  
Room Temperature ◽  
The Body ◽  
Base Temperature ◽  
Thermoelectric Cooling ◽  
X Ray ◽  
Temperature Range ◽  
Cold Stage ◽  
Reflection Geometry

A cold stage for Bragg–Brentano geometry X-ray powder diffraction is described for use in the temperature range from about 250 to 300 K. The stage is constructed in such a way that it may be removed from the diffractometer and pre-cooled to its base temperature before the sample is loaded. After loading, thermoelectric cooling maintains the specimen at low temperature (ice free) whilst the body of the stage is allowed to return to room temperature prior to remounting on the diffractometer.

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