Electron Paramagnetic Resonance and X-ray Studies of the Phase Transformation in Pb3P2O8

1975 ◽  
Vol 53 (1) ◽  
pp. 42-51 ◽  
Author(s):  
H. N. Ng ◽  
C. Calvo
Keyword(s):  
Rhombohedral Phase ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
Zero Field ◽  
Zero Field Splitting ◽  
Paramagnetic Resonance ◽  
Field Splitting ◽  
Space Group ◽  
X Ray ◽  
Monoclinic Cell

The compound Pb3P2O8 has a low temperature monoclinic phase with space group C2/c and a high temperature phase with space group [Formula: see text], both with two crystallographically inequivalent cationic sites. X-ray data taken at five temperatures have indicated that an F-centered monoclinic cell is developed prior to its transition to the rhombohedral phase. The EPR spectra at room temperature show that Mn2+ substitutes only at the cationic site on the twofold axis. A phase transition occurs at 185 °C and approaching this temperature from below the magnetic axes in the ac plane rotate continuously, by about 40°. At 185 °C the Z axis coincides with the c axis of the hexagonal cell (a* axis of the monoclinic cell). The crystal field splitting parameter b20 increases from −423 G to −222 G while b22 goes from 280 G to zero. A model based on the theory of Blume and Orbach for the zero-field splitting and with point charges as the source of the electric field is used to relate the EPR parameters to the atomic displacements.

An Electron Paramagnetic Resonance Study of Mn2+ Ions Doped in Langbeinites

1992 ◽  
Vol 47 (7-8) ◽  
pp. 849-856 ◽  
Author(s):  
T. Böttjer ◽  
G. Lehmann ◽  
M. Stockhausen
Keyword(s):  
Electron Paramagnetic Resonance Study ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
Zero Field ◽  
Zero Field Splitting ◽  
Paramagnetic Resonance ◽  
Zero Field Splitting Parameter ◽  
Splitting Parameter ◽  
Local Relaxation ◽  
Cation Size

Abstract The cubic (high temperature) phase of some langbeinites, A+2 B22+(SO4)3 with 11 different combinations of A and B type cations, doped with Mn2+, is investigated by EPR. Powder or single crystal spectra are measured at X-band. They indicate centers of axial symmetry in all cases. In 6 of the langbeinites two centers are found which differ considerably in intensity. Both centers are substitutional defects (Mn in the crystallographically nonequivalent divalent B ion sites). For the more intense one the zero field splitting parameter is proved to be negative in all cases. That center is assigned to the more spacious site which, depending on the cation size, allows for local relaxation. It is shown by comparison with predictions of the superposition model that relaxation appears to be effective

scholarly journals Broadband electron paramagnetic resonance of a molecular spin triangle

2021 ◽  
Vol 23 (36) ◽  
pp. 20268-20274
Author(s):  
Jérôme Robert ◽  
Philippe Turek ◽  
Matthieu Bailleul ◽  
Athanassios K. Boudalis
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Ground State ◽  
Zero Field ◽  
Zero Field Splitting ◽  
Field Sweep ◽  
Paramagnetic Resonance ◽  
Field Splitting ◽  
Molecular Spin ◽  
Electron Paramagnetic

A new broadband EPR spectrometer capable of measuring in frequency- and field-sweep modes is described and its functionality is demonstrated on a ferromagnetic Cu3II triangle demonstrating a moderate zero-field splitting of its quartet ground state.

An Electron Paramagnetic Resonance Investigation of Iron-Indium Pairs in Silicon

1989 ◽  
Vol 163 ◽  
Author(s):  
P. Emanuelsson ◽  
W. Gehlhoff ◽  
P. Omling ◽  
H. G. Grimmeiss
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Temperature Dependence ◽  
Zero Field ◽  
Zero Field Splitting ◽  
Paramagnetic Resonance ◽  
Field Splitting ◽  
Resonance Investigation ◽  
Electron Paramagnetic Resonance Investigation ◽  
Electron Paramagnetic

AbstractThree different Electron Paramagnetic Resonance (EPR) signals, one trigonal and two orthorhombic, which originates from iron-indium pairs in silicon are investigated. It is shown that the two orthorhombic spectra can be explained as transitions within the two doublets of a S=3/2 system with a large zero-field splitting. The temperature dependence of-the intensities reveals that the newly discovered spectrum corresponds to the lower doublet and that the zero-field splitting is 9.8 ± 2.0 cm-1.

The Dimeric Structure of Bis(1,3-Dimethylcyclopentadienyl)titanium(III) Chloride

1996 ◽  
Vol 61 (9) ◽  
pp. 1285-1294 ◽  
Author(s):  
Karel Mach ◽  
Vojtech Varga ◽  
Günter Schmid ◽  
Jörg Hiller ◽  
Ulf Thewalt
Keyword(s):  
Crystal Structure ◽  
Triplet State ◽  
Structure Analysis ◽  
Crystal Structure Analysis ◽  
Epr Spectra ◽  
Zero Field ◽  
Zero Field Splitting ◽  
Field Splitting ◽  
X Ray ◽  
Dimeric Structure

The X-ray crystal structure analysis of bis(1,3-dimethylcyclopentadienyl)titanium(III) chloride revealed that it is a centrosymmetric chlorine-bridged dimer [(η5-C5H3Me2)2Ti(μ-Cl)]2 (1) with the Ti-Ti distance of 3.9155(8) Å. Its skeleton is virtually identical with those of the [(η5-C5H5)2Ti(μ-Cl)]2 and [(η5-C5H4Me)2Ti(μ-Cl)]2 dimers. The solution EPR study proved that 1 remains a dimer in toluene whereas it dissociates in 2-methyltetrahydrofuran (MTHF) to give (η5-C5H3Me2)2TiCl . MTHF. The EPR spectra of frozen toluene solutions proved that 1 forms the triplet state whose g-tensor and zero-field splitting D are virtually the same as those of [(η5-C5H5)2Ti(μ-Cl)]2.

Structural phase transition in Zn1.98Mn0.02P2O7: EPR evidence for enhanced line broadening and large zero-field splitting parameter in high temperature phase

2013 ◽  
Vol 28 (22) ◽  
pp. 3157-3163 ◽  
Author(s):  
Santosh K. Gupta ◽  
Ramakant Mahadeo Kadam ◽  
Pradeep Samui ◽  
Krishnan Kesavaiyer ◽  
Venkataraman Natarajan ◽  
...  
Keyword(s):  
Phase Transition ◽  
Structural Phase ◽  
High Temperature Phase ◽  
Temperature Phase ◽  
Zero Field ◽  
Line Broadening ◽  
Zero Field Splitting ◽  
Zero Field Splitting Parameter ◽  
Splitting Parameter ◽  
Image Position

Abstract

Phase Transitions in Tris(3,5-dimethylpyrazol-1-yl)methane. The Structure of the High-Temperature Phase from X-ray Powder Diffraction

1997 ◽  
Vol 53 (6) ◽  
pp. 939-944 ◽  
Author(s):  
L. E. Ochando ◽  
J. Rius ◽  
D. Louër ◽  
R. M. Claramunt ◽  
C. Lopez ◽  
...  
Keyword(s):  
Powder Diffraction ◽  
High Temperature Phase ◽  
Unit Cell ◽  
Temperature Phase ◽  
Unit Cell Parameters ◽  
Space Group ◽  
X Ray ◽  
Cell Parameters ◽  
Search Structure ◽  
Patterson Search

The crystal structure of the sublimated form (m.p. = 424 K) of tris(3,5-dimethylpyrazol-l-yl)methane has been solved by a Patterson search method from laboratory X-ray powder diffraction data. Crystal data: trigonal symmetry with the unit-cell parameters a = 16.152 (1) and c = 5.353 (1) Å, space group P3, C16H22N6, Z = 3, 293 K. After indexing the powder pattern by two methods, the unit-cell parameters found were refined by a least-squares technique. A whole pattern-fitting program was used to extract the integrated intensities. The structure was solved taking a related compound as a search model and the final Rietveld refinement converged to R wp = 0.077 and R p = 0.059. This study is one of the first examples of Patterson search structure determination from an hemihedral space group using powder data. The complexity of the structural determination is increased by the presence of three molecules in the asymmetric unit.

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