EXAFS and X-ray powder diffraction studies of the spin transition molecular materials [Fe(Htrz)2(trz)](BF4) and [Fe(Htrz)3](BF4)2.H2O (Htrz = 1,2,4-4H-triazole; trz = 1,2,4-triazolato)

1995 ◽  
Vol 7 (10) ◽  
pp. 1833-1842 ◽  
Author(s):  
Alain Michalowicz ◽  
Jacques Moscovici ◽  
Bernard Ducourant ◽  
Denis Cracco ◽  
Olivier Kahn
Keyword(s):  
Powder Diffraction ◽  
Spin Transition ◽  
Molecular Materials ◽  
X Ray

An X-ray powder diffraction study of the spin-crossover transition and structure of bis(2,6-dipyrazol-1-ylpyrazine)iron(II) perchlorate

2004 ◽  
Vol 60 (1) ◽  
pp. 41-45 ◽  
Author(s):  
Victoria A. Money ◽  
Ivana Radosavljevic Evans ◽  
Jerome Elhaïk ◽  
Malcolm A. Halcrow ◽  
Judith A. K. Howard
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Spin Crossover ◽  
Spin Transition ◽  
High Spin State ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Crossover Transition

The crystal structure of the iron(II) spin-crossover compound [Fe(C10H8N6)2](ClO4)2 in the high-spin state has been solved from powder X-ray diffraction data using the DASH program and refined using Rietveld refinement. The thermal spin transition has been monitored by following the change in unit-cell parameters with temperature. The title compound has been found to undergo a crystallographic phase change, involving a doubling of the crystallographic a axis, on undergoing the spin transition.

Improvement of X-ray powder diffraction patterns of the spin transition polymer [Fe(Htrz)3](ClO4)2⋅1.85H2O

2001 ◽  
Vol 16 (1) ◽  
pp. 37-41 ◽  
Author(s):  
E. Smit ◽  
B. Manoun ◽  
S. M. C. Verryn ◽  
D. de Waal
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Spin Transition ◽  
Powder Diffraction Data ◽  
High Quality ◽  
Monoclinic System ◽  
X Ray ◽  
Cell Parameters ◽  
Diffraction Patterns

The effects of proper drying and grinding of [Fe(Htrz)3](ClO4)2⋅1.85H2O specimens on the quality of X-ray powder patterns are illustrated (Htrz=1H-1,2,4-Triazole). A procedure is suggested to achieve high-quality, reproducible X-ray powder patterns of the compound. The observed powder diffraction data of the compound are reported together with preliminary indices calculated for a monoclinic system with cell parameters a=15.8160 Å, b=20.6134 Å, c=13.0321 Å, β=103.83° and Volume=4125.633 Å3, with reliability factors: M15=10.4, F15=22.0 (0.0100; 68) and space group P21/m. This compound is very similar to the compound [Cu(Hyetrz)3](ClO4)2⋅3H2O and a comparison is made between the cell parameters of the two compounds

Computationally Assisted Structure Determination for Molecular Materials from X-ray Powder Diffraction Data

1997 ◽  
Vol 101 (33) ◽  
pp. 6532-6536 ◽  
Author(s):  
Robert B. Hammond ◽  
Kevin J. Roberts ◽  
Robert Docherty ◽  
Michael Edmondson
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Structure Determination ◽  
Powder Diffraction Data ◽  
Molecular Materials ◽  
X Ray

X-ray powder diffraction and LIESST-effect of the spin transition material [Fe(bpp)2](NCS)2·2H2O

2006 ◽  
Vol 431 (1-3) ◽  
pp. 72-77 ◽  
Author(s):  
A. Bhattacharjee ◽  
J. Kusz ◽  
V. Ksenofontov ◽  
K.H. Sugiyarto ◽  
H.A. Goodwin ◽  
...  
Keyword(s):  
Powder Diffraction ◽  
Spin Transition ◽  
X Ray ◽  
Liesst Effect

Anomalous behavior of displacement correlation function and strain in lanthanum cobalt oxide analyzed both from X-ray powder diffraction and EXAFS data

2017 ◽  
Vol 32 (S1) ◽  
pp. S151-S154 ◽  
Author(s):  
V. Efimov ◽  
V. Sikolenko ◽  
I. O. Troyanchuk ◽  
D. Karpinsky ◽  
E. Efimova ◽  
...  
Keyword(s):  
Spin State ◽  
Powder Diffraction ◽  
Spin Transition ◽  
High Spin State ◽  
Atomic Displacement ◽  
Relative Displacement ◽  
Rhombohedral Structure ◽  
Cobalt Ions ◽  
Exafs Data ◽  
X Ray

A combined X-ray powder diffraction (XPD) and high-resolution extended X-ray absorption fine structure (EXAFS) at the Co and Ga K-edges study has been performed for LaCoO3 and LaGaO3 ceramics, the latter sample was used as a reference without spin transitions. Based on the X-ray diffraction data, we have found that isotropic atomic displacement parameters (ADP) or mean-squared displacement of the Co–O bond exhibit gradual growth below ~50 K, wherein the strain dependencies testify rapid increase below 150 K for the LaCoO3 having rhombohedral structure. No similar features could be observed for LaGaO3 sample. Above ~100 K the isotropic ADP of the Co–O bond indicate a gradual growth, whereas strain curves show distinct bend near the spin-state transition temperature at about 150 K. According to the EXAFS data, the correlated parallel mean squared relative displacement (MSRD||) of Co–O and Ga–O bonds exhibit a gradual growth above 150 K; however, in the LaCoO3 this parameter is notably bigger. It is supposed that at low temperature the cobalt ions are dominantly in low-spin (LS) state, while certain amount of Co3+ ions located within the surface layer of the crystallines have high-spin state (HS). Temperature growth leads to a gradual transformation of the HS state of the cobalt ions into the highly-hybridized intermediate-spin (IS) state, while the cobalt ions located in the inner part of the crystallines remain LS configuration up to 150 K. Further temperature increase leads to a spin transition of the Co3+ ions located within the crystallines from the LS state into the IS one.

New horizons for the structural characterization of stainless steel slags by X-ray powder diffraction

2007 ◽  
Vol 2007 (suppl_26) ◽  
pp. 61-66 ◽  
Author(s):  
B. Peplinski ◽  
B. Adamczyk ◽  
G. Kley ◽  
K. Adam ◽  
F. Emmerling ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Powder Diffraction ◽  
Structural Characterization ◽  
X Ray ◽  
New Horizons

X-ray Structure Refinement and Vibrational Spectroscopy of Ca8Gd2 (PO4)6 O2

2013 ◽  
Vol 12 (10) ◽  
pp. 719-726
Author(s):  
R. Ayadi ◽  
Mohamed Boujelbene ◽  
T. Mhiri
Keyword(s):  
Solid State ◽  
General Formula ◽  
Vibrational Spectroscopy ◽  
Powder Diffraction ◽  
Infrared Spectra ◽  
Solid State Reaction ◽  
Structure Refinement ◽  
Unit Cell ◽  
Cell Group ◽  
X Ray

The present paper is interested in the study of compounds from the apatite family with the general formula Ca10 (PO4)6A2. It particularly brings to light the exploitation of the distinctive stereochemistries of two Ca positions in apatite. In fact, Gd-Bearing oxyapatiteCa8 Gd2 (PO4)6O2 has been synthesized by solid state reaction and characterized by X-ray powder diffraction. The site occupancies of substituents is0.3333 in Gd and 0.3333 for Ca in the Ca(1) position and 0. 5 for Gd in the Ca (2) position.  Besides, the observed frequencies in the Raman and infrared spectra were explained and discussed on the basis of unit-cell group analyses.

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