Investigations of the EPR Parameters and Local Structures for Two Tetragonal Cr3+ Centers in NH4Cl Crystal

2001 ◽  
Vol 56 (3-4) ◽  
pp. 326-328 ◽  
Author(s):  
Shao-Yi Wu ◽  
Wen-Chen Zheng
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Room Temperature ◽  
Zero Field ◽  
Spin Orbit ◽  
Zero Field Splitting ◽  
Paramagnetic Resonance ◽  
Resonance Parameters ◽  
Local Structures ◽  
Epr Parameters ◽  
Electron Paramagnetic

Abstract In this paper, the zero-field splittings D and g factors g||, g⟂ at room temperature for two tetragonal Cr3+ centers in NH4Cl:Cr3+ crystal have been investigated by a two-spin-orbit (S.O)-parameter model, in which both the contribution due to the S.O. coupling of central d3 ion and that of ligands are considered. From the investigations, the signs of zero-field splitting and the local structures of both centers are ob­ tained. The electron paramagnetic resonance parameters D, g|| and g⟂ of both centers are also explained.

Theoretical Investigations of the EPR Parameters for Three Tetragonal Centers in CsCl:Cr3+ Crystal

2003 ◽  
Vol 58 (2-3) ◽  
pp. 93-96
Author(s):  
Wei-Dong Chen
Keyword(s):  
Room Temperature ◽  
Coupling Parameter ◽  
Water Molecules ◽  
Zero Field ◽  
Zero Field Splitting ◽  
Paramagnetic Resonance ◽  
Theoretical Investigations ◽  
Epr Parameters ◽  
Electron Paramagnetic ◽  
Theoretical Results

The electron paramagnetic resonance parameters zero-field splitting D and g factors g∥ and g⊥ of three tetragonal centers in CsCl: Cr3+ crystal at room temperature have been investigated by a two-spin-orbit (S. O.)-coupling parameter model. In this model, the contributions arising from the S. O. coupling of the central d3 ion and the ligands are included. For center III, the very small D of the [CrCl6]3− cluster may be due to the displacement (≈ 0.506 Å ) of the two substitutional Cl− ions along the tetragonal (C4) axis. For the centers I and II, the relatively larger D results from the contribution of two or one water molecules, i. e., corresponding to [CrCl6−n(H2O)n]n−3 with, n = 2 or 1 along the C4 axis, respectively. The reasonableness of the theoretical results is discussed.

scholarly journals Defect Structures for Fe3+, Mn2+, and Ni3+ Impurities in Wuritzite GaN Crystals

2001 ◽  
Vol 56 (6-7) ◽  
pp. 473-477 ◽  
Author(s):  
Wen-Chen Zheng ◽  
Shao-Yi Wu ◽  
Jian Zi
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Strong Field ◽  
Zero Field ◽  
Spin Orbit ◽  
Defect Structures ◽  
Superposition Model ◽  
Paramagnetic Resonance ◽  
Impurity Ions ◽  
Epr Parameters ◽  
Electron Paramagnetic

Abstract Electron paramagnetic resonance (EPR) zero-field splittings D for Mn2+ and Fe3+ in wurtzite GaN crystals are studied from high-order perturbation formulas based on the spin-orbit mechanism in both weak- and strong-field schemes. From these studies it can be seen that the Mn2+ or Fe3+ impurity does not occupy the exact Ga3+ position, but is displaced by ΔR on the C3 axis. The displacements are confirmed from a study of the superposition model, based on which a normal value of b̅2 (Ro) ( ≈ -0 .34 (15) cm-1 ) for the Fe3+-N3- combination is suggested. The EPR parameters D, g|| and g ⟂ for Ni3+ in GaN crystals are also studied. It is found that Ni3+ is almost not displaced. The impurity displacements in GaN are discussed by considering the valences and radii of these impurity ions and the replaced Ga3+ ion. - Pacs: 61.16Hn; 76.30Fc; 71.70Ch

INVESTIGATIONS OF ELECTRON-PARAMAGNETIC-RESONANCE PARAMETERS OF OCTAHEDRAL (CrO6)9- and (MnO6)8- CLUSTER IN MgTiO3:Cr3+, SrTiO3:Cr3+ AND SrTiO3:Mn4+ CRYSTALS

2011 ◽  
Vol 25 (21) ◽  
pp. 1779-1785
Author(s):  
MINJIE WANG ◽  
LIANXUAN ZHU ◽  
JIANLIANG DANG
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Crystal Field ◽  
Valence State ◽  
Spin Orbit ◽  
Contribution Rate ◽  
Paramagnetic Resonance ◽  
Epr Parameters ◽  
Experimental Values ◽  
Electron Paramagnetic ◽  
G Factors

The complete high-order perturbation formulas are established by both crystal-field (CF) and charge-transfer (CT) mechanisms. The EPR g factors of MgTiO 3: Cr 3+, SrTiO 3: Cr 3+ and SrTiO 3: Mn 4+ crystals are calculated from the formulas. The calculations of the EPR g factors are in agreement with the experimental values. The contribution rate of the CT mechanism (|ΔgT/ΔgF|) to EPR parameters, increases with the growth of the valence state for the 3dn ions in the crystals. For the higher valence state 3d3 ion Mn 4+ in crystals, the explanation of the EPR parameters reasonably involves both CF and CT mechanisms. The g values are also given from one-spin-orbit-parameter model and crystal-field (CF) mechanism for comparison.

On The EPR Parameters of Divalent Cobalt in ZnX (X = S, Se, Te) And CdTe

2004 ◽  
Vol 59 (12) ◽  
pp. 938-942 ◽  
Author(s):  
Shao-Yi Wu ◽  
Hui-Ning Dong
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Charge Transfer ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Paramagnetic Resonance ◽  
A Value ◽  
Epr Parameters ◽  
Divalent Cobalt ◽  
Structure Constants ◽  
Electron Paramagnetic

The electron paramagnetic resonance (EPR) parameters g and the hyperfine structure constants A of Co2+ in ZnX (X = S, Se, Te) and CdTe are studied, using the perturbation formulas of the EPR parameters for a 3d7 ion in tetrahedra based on two mechanism models. In these formulas, both the contributions from the conventional crystal-field (CF) mechanism and those from the charge-transfer (CT) mechanism are taken into account. According to the investigations, the sign of the g-shift ΔgCT from the CT mechanism is the same as ΔgCF from the CF mechanism, whereas the contributions to the A value from the CF and CT mechanisms have opposite signs. Particularly, the contributions to the EPR parameters from the CT mechanism increase rapidly with increase of the spin-orbit coupling coefficient of the ligand and the covalency effect of the systems, i. e. S2− < Se2− < Te2−.

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.

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