Crystal Structure Refinement of the Layered Copper-Titanium Perovskites Ln2Ba2Cu2Ti2O11 (Ln = La, Nd) from Neutron Powder Diffraction Data

1994 ◽  
Vol 6 (11) ◽  
pp. 2118-2122 ◽  
Author(s):  
Pedro Gomez-Romero ◽  
Maria Rosa Palacin ◽  
Juan Rodriguez-Carvajal
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Structure Refinement ◽  
Neutron Powder Diffraction ◽  
Crystal Structure Refinement ◽  
Powder Diffraction Data ◽  
Neutron Powder Diffraction Data

The crystal structure of perdeuterated methanol monoammoniate (CD3OD·ND3) determined from neutron powder diffraction data at 4.2 and 180 K

2009 ◽  
Vol 42 (6) ◽  
pp. 1054-1061 ◽  
Author(s):  
A. D. Fortes ◽  
I. G. Wood ◽  
K. S. Knight
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Rietveld Method ◽  
Neutron Powder Diffraction ◽  
Relative Volume ◽  
Powder Diffraction Data ◽  
Orthorhombic Space Group ◽  
Neutron Powder Diffraction Data

The crystal structure of perdeuterated methanol monoammoniate, CD3OD·ND3, has been solved from neutron powder diffraction data collected at 4.2 and 180 K. The crystal structure is orthorhombic, space groupPbca(Z= 8), with unit-cell dimensionsa= 11.02320 (7),b= 7.66074 (6),c= 7.59129 (6) Å,V= 641.053 (5) Å3[ρcalc= 1162.782 (9) kg m−3] at 4.2 K, anda= 11.21169 (5),b= 7.74663 (4),c= 7.68077 (5) Å,V= 667.097 (4) Å3[ρcalc= 1117.386 (7) kg m−3] at 180 K. The crystal structure was determined byab initiomethods from the powder data; atomic coordinates and anisotropic displacement parameters were subsequently refined by the Rietveld method toRp< 3% at both temperatures. The crystal comprises a sheet-like structure in thebccrystallographic plane, consisting of strongly hydrogen bonded elements; these sheets are stacked along theaaxis, and adjacent sheets are linked by what may be comparatively weak C—D...O hydrogen bonds. Within the strongly bonded sheet structure, ND3molecules are tetrahedrally coordinated by the hydroxy moieties of the methanol molecule, accepting one hydrogen bond (O—D...N) of length ∼1.75 Å, and donating three hydrogen bonds (N—D...O) of length 2.15–2.25 Å. Two of the methyl deuterons appear to participate in weak interlayer hydrogen bonds (C—D...O) of length 2.7–2.8 Å. The hydrogen bonds are ordered at both 4.2 and 180 K. The relative volume change on warming from 4.2 to 180 K, ΔV/V, is +4.06%, which is comparable to, but more nearly isotropic (as determined from the relative change in axial lengths,e.g.Δa/a) than, that observed in deuterated methanol monohydrate.

Crystal Structure of La4Si2O7N2Analyzed by the Rietveld Method Using the Time-of-Flight Neutron Powder Diffraction Data

2003 ◽  
Vol 15 (5) ◽  
pp. 1099-1104 ◽  
Author(s):  
Junichi Takahashi ◽  
Hisanori Yamane ◽  
Naoto Hirosaki ◽  
Yoshinobu Yamamoto ◽  
Takayuki Suehiro ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Rietveld Method ◽  
Time Of Flight ◽  
Neutron Powder Diffraction ◽  
Powder Diffraction Data ◽  
Neutron Powder Diffraction Data

Crystal-structure refinement of τ3-Cr4(Al, Si)11 by full-profile Rietveld analysis

2007 ◽  
Vol 22 (3) ◽  
pp. 253-255 ◽  
Author(s):  
Franz Weitzer ◽  
Hailin Chen ◽  
Julius C. Schuster
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Ternary Phase ◽  
Structure Refinement ◽  
Rietveld Analysis ◽  
Crystal Structure Refinement ◽  
Powder Diffraction Data ◽  
Full Profile

Crystal structure of the triclinic ternary phase Cr4(Al, Si)11 was investigated by full-profile Rietveld analysis of powder diffraction data. Four hundred eighty-four reflections were refined to a final RBragg value of 5.00%. Cr4(Al, Si)11 is isostructural to Mn4Al11. Silicon atoms enter into the structure by partially replacing aluminium on the Al(1) and Al(2) sites.

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