Magnetic structure of bornite, Cu5FeS4

1981 ◽  
Vol 59 (4) ◽  
pp. 535-539 ◽  
Author(s):  
M. F. Collins ◽  
G. Longworth ◽  
M. G. Townsend
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Magnetic Structure ◽  
Magnetic Phase ◽  
Magnetic Ordering ◽  
Neutron Powder Diffraction ◽  
Spin Rotation ◽  
Neutron Diffraction Data ◽  
X Ray ◽  
Antiferromagnetic Ordering

Neutron powder diffraction techniques have been used to investigate the magnetic structure of bornite, Cu5FeS4. Below the antiferromagnetic ordering temperature of 76 ± 2 K extra peaks appear in the diffraction pattern corresponding to magnetic ordering. The data are consistent with an antiferromagnetic alignment of iron atoms with moments of 4.4 ± 0.3 μB on the iron sites proposed by Koto and Morimoto on the basis of X-ray measurements of the crystal structure. Mössbauer and neutron diffraction data suggest that the second magnetic phase transition at 8 K arises from a spin rotation. Since the magnetic structure gives only superexchange paths between iron atoms through two or more anions, it is difficult to understand why the Néel temperature is so high without invoking small moments on copper atoms

Structural and Magnetic Properties of La0.7Sr0.3Mn1-xNixO3 (x=0.05, 0.1, 0.2, 0.3, 0.4)

2011 ◽  
Vol 1327 ◽  
Author(s):  
Thomas F. Creel ◽  
Jinbo B. Yang ◽  
Mehmet Kahveci ◽  
Jagat Lamsal ◽  
Satish K. Malik ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Neutron Diffraction ◽  
Diffraction Data ◽  
Magnetic Measurements ◽  
Magnetic Ordering ◽  
Neutron Diffraction Data ◽  
Space Group ◽  
X Ray ◽  
Antiferromagnetic Ordering ◽  
Structural And Magnetic Properties

ABSTRACTWe have studied the structural and magnetic properties of La0.7Sr0.3Mn1-xNixO3 (x=0.05, 0.10, 0.20, 0.30, and 0.40) perovskites using x-ray and neutron diffraction and magnetic measurements. To our knowledge, there exists no neutron diffraction data available for this group of perovskite compositions. Neutron (λ = 1.479Å) and x-ray (λ = 1.5481Å; Cu Kα) powder diffraction indicate that for x ≥ 0.1 all samples are two-phase with a rhombohedral perovskite structure (space group R-3c) and a small amount of NiO (space group Fm3m). Neutron diffraction data for the perovskite phase at 12K and 300K show ferromagnetic ordering for x ≤ 0.2 and antiferromagnetic ordering for x = 0.4. However, for x = 0.3, neutron diffraction data at 12K show coexisting ferromagnetic and antiferromagnetic ordering while at 300K no magnetic ordering is found. Magnetic measurements indicate that the Curie temperature decreases with increasing Ni content. The NiO phase for all samples was found to have antiferromagnetic ordering at 12K and 300K. The magnetic measurements are consistent with the neutron diffraction data and together indicate long-range magnetic ordering for samples at low temperature and transitions from ferromagnetic to paramagnetic to antiferromagnetic ordering for samples at room temperature.

Structural behaviour of synthetic Co2SiO4 at low temperatures

2008 ◽  
Vol 64 (6) ◽  
pp. 661-668 ◽  
Author(s):  
Andrew Sazonov ◽  
Martin Meven ◽  
Vladimir Hutanu ◽  
Volker Kaiser ◽  
Gernot Heger ◽  
...  
Keyword(s):  
Phase Transition ◽  
Low Temperatures ◽  
Magnetic Phase ◽  
Structural Phase ◽  
Magnetic Ordering ◽  
Structure Parameters ◽  
Structural Behaviour ◽  
X Ray ◽  
Anomalous Thermal Expansion ◽  
Olivine Structure

Synthetic Co2SiO4 has an olivine structure with isolated SiO4 groups (space group Pnma) and shows magnetic ordering below 50 K. Single-crystal neutron diffraction was applied to determine precise crystal structure parameters at low temperatures. No structural phase transition was revealed in the temperature range 2.5–300 K. Lattice parameters were determined by high-resolution X-ray powder diffraction between 15 and 300 K. There is a clear evidence of an anomalous thermal expansion related to the magnetic phase transition which can be attributed to magnetostriction.

Synthesis, Crystal and Magnetic Structure of the New Double Perovskite Ba2MnMoO6

2003 ◽  
Vol 58 (6) ◽  
pp. 571-576 ◽  
Author(s):  
M. J. Martínez-Lope ◽  
J. A. Alonso ◽  
M. T. Casais
Keyword(s):  
Magnetic Structure ◽  
Room Temperature ◽  
Double Perovskite ◽  
Electronic Configuration ◽  
Neutron Powder Diffraction ◽  
X Ray ◽  
Antiferromagnetic Ordering ◽  
Citrate Precursors ◽  
Polycrystalline Form

We describe the preparation and characterization of a new double perovskite of formula Ba2MnMoO6. It has been obtained in polycrystalline form by thermal treatment, in a H2/N2 flow, of previously decomposed citrate precursors. This material has been studied by X-ray (XRD) and neutron powder diffraction (NPD): it crystallizes, at room temperature, in the cubic space group Fm3̄̄̄̄̄m, and shows an almost perfect ordering between Mn2+ and Mo6+ cations at the B substructure. Below TN = 10.8 K, it experiences a long range antiferromagnetic ordering that was followed from sequential NPD data. The low-temperature magnetic structure is defined by the propagation vector k = (1⁄2, 1⁄2, 1⁄2). The ordered magnetic moment of Mn is found to be 4.04(8) μB at 2 K, suggesting a divalent oxidation state for Mn cations, in a high spin t32ge2g (S = 5/2) electronic configuration.

Crystal Structure of the Compound Bi2Zn2/3Nb4/3O7

2002 ◽  
Vol 17 (6) ◽  
pp. 1406-1411 ◽  
Author(s):  
Igor Levin ◽  
Tammy G. Amos ◽  
Juan C. Nino ◽  
Terrell A. Vanderah ◽  
Ian M. Reaney ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Neutron Diffraction ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Neutron Powder Diffraction ◽  
Neutron Diffraction Data ◽  
Structural Refinement ◽  
Large Component ◽  
X Ray ◽  
Thermal Displacements

The crystal structure of Bi2Zn2/3Nb4/3O7 was determined using a combination of electron, x-ray, and neutron powder diffraction. The compound crystallizes with a monoclinic zirconolite-like structure [C2/c (No.15) space group, a = 13.1037(9) Å, b = 7.6735(3) Å, c = 12.1584(6) Å, β = 101.318(5)°]. According to structural refinement using neutron diffraction data, Nb preferentially occupies six-fold coordinated sites in octahedral sheets parallel to the (001) planes, while Zn is statistically distributed between two half-occupied (5 + 1)-fold coordinated sites near the centers of six-membered rings of [Nb(Zn)O6] octahedra. The Nb/Zn cation layers alternate along the c-axis with Bi-layers, in which Bi cations occupy both eight- and seven-fold coordinated sites. The eight-fold coordinated Bi atoms exhibited strongly anisotropic thermal displacements with an abnormally large component directed approximately along the c-axis (normal to the octahedral layers).

Synthesis, structural, magnetic and phase-transition studies of the ferromagnetic La2CoMnO6 double perovskite by symmetry-adapted modes

2015 ◽  
Vol 44 (31) ◽  
pp. 13867-13880 ◽  
Author(s):  
B. Orayech ◽  
I. Urcelay-Olabarria ◽  
G. A. López ◽  
O. Fabelo ◽  
A. Faik ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Double Perovskite ◽  
Solid State Reaction Method ◽  
Rietveld Analysis ◽  
Neutron Diffraction Data ◽  
Reaction Method ◽  
X Ray ◽  
Space Groups ◽  
Transition Studies

A powdered La2CoMnO6 double perovskite was synthesized by the solid-state reaction method, and its crystal structure and phase-transitions were investigated by (Mode Crystallography) Rietveld analysis using X-ray and neutron diffraction data. Three indistinguishable ferromagnetic models with the space groups P21/n and P2′1/n′ are proposed.

scholarly journals Synthesis, Crystal Structure and Magnetic Properties of Bixbyite-type Vanadium Oxide Nitrides

2009 ◽  
Vol 64 (3) ◽  
pp. 281-286 ◽  
Author(s):  
Suliman Nakhal ◽  
Wilfried Hermes ◽  
Thorsten Ressler ◽  
Rainer Pöttgen ◽  
Martin Lerch
Keyword(s):  
Crystal Structure ◽  
Vanadium Oxide ◽  
Magnetic Ordering ◽  
Vanadium Oxides ◽  
Detectable Amount ◽  
X Ray Diffraction ◽  
X Ray ◽  
Vanadium Sulfide ◽  
Structure Result ◽  
X Ray Absorption

Ammonolysis of vanadium sulfide leads to the formation of bixbyite-type vanadium oxide nitrides. Small amounts of nitrogen incorporated in the structure result in the stabilization of the bixbyite type not known for vanadium oxides. The crystal structure was investigated using X-ray diffraction and X-ray absorption spectroscopy. At temperatures above 550 °C the powders decompose to corundumtype V2O3 containing no detectable amount of nitrogen. Below 39 K magnetic ordering is observed.

Structure of ammonium hydrogen succinate above and below the phase transition around 170K

1996 ◽  
Vol 52 (2) ◽  
pp. 323-327 ◽  
Author(s):  
A. Hirano ◽  
Y. Kubozono ◽  
H. Maeda ◽  
H. Ishida ◽  
S. Kashino
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Hydrogen Bonds ◽  
Order Phase Transition ◽  
Space Group ◽  
X Ray ◽  
Ammonium Hydrogen ◽  
Significant Change ◽  
Short Hydrogen Bonds ◽  
Second Order Phase Transition

For crystals of ammonium hydrogen succinate it is known that the space group is P{\bar 1} with Z = 2 at 293 K and the second-order phase transition occurs around 170 K. X-ray crystal structure analyses above and below 170 K have been carried out in order to study the change in mode of short hydrogen bonds between the hydrogen succinate ions. The space group was determined to be P{\bar 1} at 150 and 190 K by structure analysis. No ordering of the H-atom positions in the short hydrogen bonds occurs by the phase transition. The hydrogen bonds show a decrease in the O...O distances with a decrease in temperature from 290 to 190 K, but no significant change in the geometries between 190 and 150 K. Disorder of the NH4 + ion is not observed at 297, 190 and 150 K. Significant change through the phase transition is found only in the geometry of one of the N—H...O hydrogen bonds between ammonium and hydrogen succinate ions.

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