scholarly journals On the magnetic structure and magnetic behaviour of the most distorted member of the series of RNiO3 perovskites (R= Lu)

2022 ◽  
Author(s):  
Federico Serrano ◽  
Maria Teresa Fernandez-Diaz ◽  
Jose L. Martinez ◽  
Jose Antonio Alonso
Keyword(s):  
Crystal Structure ◽  
Magnetic Structure ◽  
Powder Diffraction ◽  
Temperature Region ◽  
Magnetic Behaviour ◽  
Neutron Powder Diffraction

The crystal structure of LuNiO3 perovskite has been examined below RT and across TN = 125 K by neutron powder diffraction. In this temperature region (2-298 K), well below the...

scholarly journals Hydroflux Synthesis, Chemical and Thermal Instability, Crystal and Magnetic Structures of the Oxo-Hydroxoferrate K2–xFe4O7–x(OH)x

2018 ◽  
Author(s):  
Ralf Albrecht ◽  
Jens Hunger ◽  
Theresa Block ◽  
Rainer Pöttgen ◽  
Anatoliy Senyshyn ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Magnetic Structure ◽  
Powder Diffraction ◽  
Thermal Instability ◽  
Neutron Powder Diffraction ◽  
Potassium Ions ◽  
Ambient Conditions ◽  
Magnetic Structures ◽  
Vertex Sharing ◽  
Crystal And Magnetic Structures

The reaction of Fe(NO3)3∙9 H2O with KOH under hydroflux conditions at about 200 °C produces red crystals of K2−xFe4O7–x(OH)x in a quantitative yield. In the crystal structure, edge-sharing [FeO6] octahedra form 2D-[Fe2O6] honeycomb nets. Pillars consisting of pairs of vertex-sharing [FeO4] tetrahedra link the honeycomb layers and form columnar halls in which the potassium ions are located. The trigonal (P3̅1m) and the hexagonal (P63/mcm) polytypes of K2−xFe4O7–x(OH)x show oriented intergrowth. The sub-stoichiometric potassium content (x = 0.3) is compensated by hydroxide ions. K2−xFe4O7–x(OH)x is an antiferromagnet above 2 K and its magnetic structure was determined by neutron powder diffraction. Under ambient conditions K2−xFe4O7–x(OH)x hydrolyzes and K2CO3·H2O forms gradually on the surface of the K2−xFe4O7–x(OH)x crystals. Upon annealing at air at about 500 °C, the potassium atoms in the columnar halls start to order into a superstructure.<br>

Use of Neutron Diffraction for Describing Texture of Isostatically-Pressed Molybdite Powders

2005 ◽  
Vol 105 ◽  
pp. 83-88 ◽  
Author(s):  
H. Sitepu ◽  
Heinz Günter Brokmeier
Keyword(s):  
Crystal Structure ◽  
Neutron Diffraction ◽  
Powder Diffraction ◽  
Quantitative Description ◽  
Neutron Powder Diffraction ◽  
Powder Diffraction Data ◽  
Neutron Powder Diffraction Data ◽  
Pole Figures ◽  
Diffraction Patterns ◽  
Excellent Tool

The modelling and/or describing of texture (i.e. preferred crystallographic orientation (PO)) is of critical importance in powder diffraction analysis - for structural study and phase composition. In the present study, the GSAS Rietveld refinement with generalized spherical harmonic (GSH) was used for describing isostatically-pressed molybdite powders neutron powder diffraction data collected in the ILL D1A instrument. The results showed that for texture in a single ND data of molybdite the reasonable crystal structure parameters may be obtained when applying corrections to intensities using the GSH description. Furthermore, the WIMV method was used to extract the texture description directly from a simultaneous refinement with 1368 whole neutron diffraction patterns taken from the sample held in a variety of orientations in the ILL D1B texture goniometer. The results provided a quantitative description of the texture refined simultaneously with the crystal structure. Finally, the (002) molybdite pole-figures were measured using the GKSS TEX2 texture goniometer. The results showed that neutron diffraction is an excellent tool to investigate the texture in molybdite.

A Study of the Magnetic Structure of LaMn2O5from Neutron Powder Diffraction Data

2005 ◽  
Vol 2005 (4) ◽  
pp. 685-691 ◽  
Author(s):  
Angel Muñoz ◽  
Jose A. Alonso ◽  
María T. Casais ◽  
María J. Martínez-Lope ◽  
Jose L. Martínez ◽  
...  
Keyword(s):  
Magnetic Structure ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Neutron Powder Diffraction ◽  
Powder Diffraction Data ◽  
Neutron Powder Diffraction Data

Neutron powder diffraction study of the magnetic structure of EuZrO3

2014 ◽  
Vol 26 (9) ◽  
pp. 095401 ◽  
Author(s):  
Maxim Avdeev ◽  
Brendan J Kennedy ◽  
Taras Kolodiazhnyi
Keyword(s):  
Diffraction Study ◽  
Magnetic Structure ◽  
Powder Diffraction ◽  
Neutron Powder Diffraction

scholarly journals Neutron diffraction investigation of the temperature dependence of crystal structure and thermal motions of red HgI2

2007 ◽  
Vol 63 (6) ◽  
pp. 828-835 ◽  
Author(s):  
Dieter Schwarzenbach ◽  
Henrik Birkedal ◽  
Marc Hostettler ◽  
Peter Fischer
Keyword(s):  
Crystal Structure ◽  
Neutron Diffraction ◽  
Powder Diffraction ◽  
Soft Mode ◽  
Layer Structure ◽  
Neutron Powder Diffraction ◽  
Force Constants ◽  
Quantum Oscillator ◽  
Thermal Displacement ◽  
Tetrahedral Layer

The structure of, and anisotropic thermal motions in, the red semiconductor tetrahedral layer structure of HgI2 have been studied with neutron powder diffraction as a function of temperature from 10 to 293 K. Average thermal displacement parameters U eq of the two atoms are comparable in size at 10 K, but U eq(Hg) increases considerably faster with temperature than U eq(I), the Hg—I bond being highly non-rigid. The anisotropic displacement tensor U (I) is strongly anisotropic with one term about twice as large as the others, while U (Hg) is nearly isotropic. All displacement tensor elements, except U 22(I), increase faster with temperature than harmonic quantum oscillator curves indicating a softening of the isolated-atom potentials at large amplitudes. A lattice dynamical model provides arguments that the anisotropic thermal motions of I are dominated by a soft mode with a wavevector at the [½ ½ 0] boundary of the Brillouin zone consisting essentially of coupled librations of the HgI4 tetrahedra, and by translations of the entire layer. The large vibration amplitudes of Hg suggest weak Hg–I force constants compared with the I–I force constants, allowing Hg to move quite freely inside the tetrahedra. The libration mode induces dynamic deformations of the Hg—I bond with twice its frequency. This provides a mechanism for the anharmonicity and may explain the lightening of the color from red to orange upon cooling at ca 80 K.

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