High Resolution Neutron Powder Diffraction Studies of the Ferroelastic Phase Transition in LaNbO4

1989 ◽  
Vol 166 ◽  
Author(s):  
W I F David
Keyword(s):  
Phase Transition ◽  
High Resolution ◽  
Powder Diffraction ◽  
Structural Phase ◽  
Strain Tensor ◽  
Neutron Powder Diffraction ◽  
Line Broadening ◽  
Neutron Powder Diffraction Data ◽  
Ferroelastic Phase Transition ◽  
Principal Axes

ABSTRACTAnalysis of high resolution neutron powder diffraction data of ferroelastic LaNbO4 indicates a monoclinic to tetragonal structural phase transition that is accompanied by anomalous line broadening. The origins of this line broadening have been investigated using a novel modification of the Rietveld technique. The results show that strain broadening is associated with the ferroelastic phase transition both above and below the transition temperature. This anomalous ‘microstrain’ is well-described by a second rank strain tensor, the principal axes of which are collinear with the spontaneous lattice strain. This phenomenon may be a general feature of proper ferroelastic phase transitions.

Equation of state and phase transition of deuterated ammonia monohydrate (ND3⋅D2O) measured by high-resolution neutron powder diffraction up to 500 MPa

2009 ◽  
Vol 131 (15) ◽  
pp. 154503 ◽  
Author(s):  
A. Dominic Fortes ◽  
Emmanuelle Suard ◽  
Marie–Hélène Lemée-Cailleau ◽  
Christopher J. Pickard ◽  
Richard J. Needs
Keyword(s):  
Phase Transition ◽  
High Resolution ◽  
Equation Of State ◽  
Powder Diffraction ◽  
Neutron Powder Diffraction

Neutron powder diffraction study of the mixed-valence vanadium pyrophosphate RbV3P4O17

1992 ◽  
Vol 202 (3-4) ◽  
Author(s):  
Sue-Lein Wang ◽  
James W. Richardson
Keyword(s):  
High Resolution ◽  
Diffraction Study ◽  
Rietveld Refinement ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Mixed Valence ◽  
Neutron Powder Diffraction ◽  
Powder Diffraction Data ◽  
Resolution Time ◽  
Neutron Powder Diffraction Data

AbstractRietveld refinement using high-resolution time-of-flight neutron powder diffraction data is reported for a mixed-valence vanadium pyrophosphate of RbV

The Crystal Structure of [Mg2(H2O)6(HCO3)3]+Cl–, Containing a Magnesium-based Hetero-polycation

2008 ◽  
Vol 63 (12) ◽  
pp. 1347-1351 ◽  
Author(s):  
Robert E. Dinnebier ◽  
Martin Jansen
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
High Resolution ◽  
Structural Phase Transition ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Structural Phase ◽  
Close Packing ◽  
Powder Diffraction Data ◽  
Hydrogen Carbonate

The crystal structure of di-magnesium hexahydrate trihydrogencarbonate chloride, [Mg2(H2O)6- (HCO3)3]+Cl−, has been determined from high-resolution laboratory powder diffraction data (lattice parameters at r. t.: a = 8.22215(2), c = 39.5044(2) Å, V = 2312.85(2) Å3, space group R3̄̄c, Z = 6). The crystal structure of [Mg2(H2O)6(HCO3)3]+Cl− is built up of alternating sheets of Cl− anions and complex [Mg2(H2O)6(HCO3)3]+ cations consisting of two Mg(OH2)3O3 octahedra interconnected by three disordered hydrogen carbonate groups. The packing can be described as a cubic close packing of [Mg2(H2O)6(HCO3)3]+ cations with the Cl− anions filling all octahedral voids. In the temperature range from r. t. up to decomposition, which takes place in the range 398 K < T < 413 K, no structural phase transition occurs.

Structural Phase Transition of Orthorhombic LaCrO3 Studied by Neutron Powder Diffraction

2000 ◽  
Vol 154 (2) ◽  
pp. 524-529 ◽  
Author(s):  
K. Oikawa ◽  
T. Kamiyama ◽  
T. Hashimoto ◽  
Y. Shimojyo ◽  
Y. Morii
Keyword(s):  
Phase Transition ◽  
Structural Phase Transition ◽  
Powder Diffraction ◽  
Structural Phase ◽  
Neutron Powder Diffraction

The ab initio crystal structure determination of vapour-deposited methyl fluoride by high-resolution neutron powder diffraction

1996 ◽  
Vol 52 (5) ◽  
pp. 892-895 ◽  
Author(s):  
R. M. Ibberson ◽  
M. Prager
Keyword(s):  
Crystal Structure ◽  
High Resolution ◽  
Ab Initio ◽  
Bond Length ◽  
Powder Diffraction ◽  
Structure Refinement ◽  
Neutron Powder Diffraction ◽  
Methyl Halides ◽  
Methyl Fluoride ◽  
Neutron Powder Diffraction Data

The crystal structure of methyl fluoride (m.p. = 131 K, b.p. = 195 K) at 5 K has been solved ab initio from high-resolution neutron powder diffraction data. A good quality powder sample was produced using a vapour deposition technique and enabled an accurate and precise structure refinement to be carried out; the C—F bond length is 1.399 (4) Å, and the average C—D bond length is 1.070 (4) Å. The monoclinic structure may be described in terms of dipole-dipole intermolecular interactions and is distinct from the structures of the other methyl halides.

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