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−.

Theoretical investigations of electron paramagnetic resonancegfactors in ZnSe:Ti2+, CdTe:Ti2+and ZnSe:V3+crystals

2012 ◽  
Vol 45 (5) ◽  
pp. 972-975
Author(s):  
Lianxuan Zhu ◽  
Minjie Wang
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Charge Transfer ◽  
Coupling Effect ◽  
Orbit Coupling ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Paramagnetic Resonance ◽  
Theoretical Investigations ◽  
The One ◽  
Electron Paramagnetic

The electron paramagnetic resonance (EPR)g-factor formulas are constructed for ZnSe:Ti2+, CdTe:Ti2+and ZnSe:V3+crystals based on the contributions of the charge-transfer levels and the spin-orbit coupling effect of the central ion and the ligands. The EPRgfactors are calculated from these formulas, and the calculated values agree well with the experimental ones. The contribution rates of the charge-transfer levels are 10.1, 7.6 and 24.9% for ZnSe:Ti2+, CdTe:Ti2+and ZnSe:V3+crystals, respectively. Thegfactors obtained from the one-spin-orbit-parameter model are also given for comparison.

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.

Investigations of the EPR Parameters and Local Lattice Structure for the Rhombic Cu2+ Centre in TZSH Crystal

2016 ◽  
Vol 71 (3) ◽  
pp. 255-260 ◽  
Author(s):  
Chao-Ying Li ◽  
Shi-Fei Liu ◽  
Jin-Xian Fu
Keyword(s):  
Lattice Structure ◽  
Spin Orbit Coupling ◽  
Paramagnetic Resonance ◽  
Local Lattice ◽  
Ligand Orbital ◽  
Epr Parameters ◽  
Structure Constants ◽  
Electron Paramagnetic ◽  
D Orbitals ◽  
Good Agreement

AbstractThe electron paramagnetic resonance (EPR) parameters [i.e. g factors gi (i=x, y, z) and hyperfine structure constants Ai] and the local lattice structure for the Cu2+ centre in Tl2Zn(SO4)2·6H2O (TZSH) crystal were theoretically investigated by utilising the perturbation formulae of these parameters for a 3d9 ion under rhombically elongated octahedra. In the calculations, the admixture of d orbitals in the ground state and the ligand orbital and spin-orbit coupling interactions are taken into account based on the cluster approach. The theoretical EPR parameters show good agreement with the observed values, and the Cu2+–H2O bond lengths are obtained as follows: Rx≈1.98 Å, Ry≈2.09 Å, Rz≈2.32 Å. The results are discussed.

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.

scholarly journals Investigation Of The Epr Parameters Of An Orthorhombic Cu2+ Center In Cs2zncl4 Crystal

2005 ◽  
Vol 60 (5) ◽  
pp. 373-375 ◽  
Author(s):  
Hui-Ning Dong ◽  
Shao-Yi Wu ◽  
Xian-Rong Liu ◽  
Wei-Dong Chen
Keyword(s):  
Crystal Structure ◽  
Electron Paramagnetic Resonance ◽  
Hyperfine Structure ◽  
Hamiltonian Matrix ◽  
Superposition Model ◽  
Paramagnetic Resonance ◽  
Epr Parameters ◽  
Structure Constants ◽  
Crystal Field Parameters ◽  
Electron Paramagnetic

The electron paramagnetic resonance (EPR) anisotropic g-factors gx, gy and gz and hyperfine structure constants Ax, Ay and Az of Cu2+ in Cs2ZnCl4 crystal are theoretically investigated by the method of diagonalizing the full Hamiltonian matrix. The crystal-field parameters are obtained from the crystal structure by the superposition model. The results, agreeing reasonably with the observed values, are 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

Interpretation of the Electron Paramagnetic Resonance Spectra of Copper(II)–Tyrosine Complex

2017 ◽  
Vol 73 (1) ◽  
pp. 75-78
Author(s):  
Xiao-Hui Xu ◽  
Min-Quan Kuang
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Mean Value ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Elongation Ratio ◽  
Paramagnetic Resonance ◽  
Local Distortion ◽  
The Mean ◽  
Electron Paramagnetic ◽  
Ligand Bond

AbstractThe electron paramagnetic resonance (EPR) spectra of [Cu(l-tyrosine)2]n (CuA) were interpreted based on the fourth-order perturbation treatments where the contributions due to the local distortion, ligand orbit and spin-orbit coupling were included. The calculated band transitions ${{\text{d}}_{{{\text{x}}^2} - {{\text{y}}^2}}}$ to dxy (≈16412 cm−1) and ${{\text{d}}_{{{\text{z}}^2}}}$ (≈14845 cm−1) agree well with the band analysis results ${\text{(}}{{\text{d}}_{{{\text{x}}^2} - {{\text{y}}^2}}} \to {{\text{d}}_{{\text{xy}}}}$≈16410 and ${{\text{d}}_{{{\text{x}}^2} - {{\text{y}}^2}}} \to {{\text{d}}_{{{\text{z}}^2}}}$≈14850 cm−1). The unresolved separations ${{\text{d}}_{{{\text{x}}^2} - {{\text{y}}^2}}} \to {{\text{d}}_{{\text{xz}}}}$ and ${{\text{d}}_{{{\text{x}}^2} - {{\text{y}}^2}}} \to {{\text{d}}_{{\text{yz}}}}$ in the absorption spectra were evaluated as 26283 and 26262 cm−1, respectively. For CuA, copper chromophores in 1,3-diaminorpropane isophtalate copper(II) complex (CuB) and N-methyl-1,2-diaminoetaane-bis copper(II) polymer (CuC), the transition ${{\text{d}}_{{{\text{x}}^2} - {{\text{y}}^2}}} \to {{\text{d}}_{{\text{xy}}}}$ (=E1≈10Dq) suffered an increase with a decrease in R̅L which was evaluated as the mean value of the copper-ligand bond lengths. The correlations between the tetragonal elongation ratio ρ (=(Rz–R̅L)/R̅L) (or the ratio G=(gz–ge)/((gx+gy)/2–ge)) and the g isotropy gav (=(gx+gy+gz)/3) (or the covalency factor N) for CuA, CuB and CuC were acquired and all the results were discussed.

Theoretical Studies on the Local Structure and Electron Paramagnetic Resonance Parameters for Cu2+ Centers in TiO2 with one Oxygen Vacancy Adjacent

2013 ◽  
Vol 68 (10-11) ◽  
pp. 605-609 ◽  
Author(s):  
Chao-Ying Li ◽  
Xue-Mei Zheng ◽  
Jie He
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Oxygen Vacancy ◽  
Local Structure ◽  
Defect Model ◽  
Paramagnetic Resonance ◽  
Epr Parameters ◽  
Structure Constants ◽  
Electron Paramagnetic ◽  
Theoretical Results ◽  
Good Agreement

Based on the defect model that the impurity Cu2+ in TiO2 on the octahedral Ti4+ site is associated with one oxygen vacancy VO along the C2 axis, the electron paramagnetic resonance (EPR) parameters, i. e., the g factors gi (i = x;y; z) and the hyperfine structure constants At, of the Cu2+-VOcenter in TiO2 are calculated by using the perturbation formulas of these parameters for a 3d9 ion in a rhombically elongated octahedra. From this study, the impurity Cu2+ is found to be away from VO by a distance Dz (≈ 0:33 Å) along the C2 axis, meanwhile the four O2- ions in the plane perpendicular to the C2 axis may be shifted by Dx (≈ 0:28 Å) towards VO due to the electrostatic interaction between these ions and VO. The theoretical results based on the above local structure distortions show good agreement with the experimental data.

Studies of local structures for Cu2+ centers in M2Zn(SO4)2·6H2O (M = NH4 and Rb) crystals

2021 ◽  
Vol 76 (4) ◽  
pp. 299-304
Author(s):  
Fu Chen ◽  
Jian-Rong Yang ◽  
Zi-Fa Zhou
Keyword(s):  
Crystal Field ◽  
Elongation Ratio ◽  
Paramagnetic Resonance ◽  
Local Structures ◽  
Epr Parameters ◽  
Structure Constants ◽  
Crystal Field Parameters ◽  
Electron Paramagnetic ◽  
Theoretical Results ◽  
Good Agreement

Abstract The electron paramagnetic resonance (EPR) parameters (g factor g i , and hyperfine structure constants A i , with i = x, y, z) and local structures for Cu2+ centers in M2Zn(SO4)2·6H2O (M = NH4 and Rb) are theoretically investigated using the high order perturbation formulas of these EPR parameters for a 3d 9 ion under orthorhombically elongated octahedra. In the calculations, contribution to these EPR parameters due to the admixture of d-orbitals in the ground state wave function of the Cu2+ ion are taken into account based on the cluster approach, and the required crystal-field parameters are estimated from the superposition model which enables correlation of the crystal-field parameters and hence the studied EPR parameters with the local structures of the Cu2+ centers. Based on the calculations, the Cu–H2O bonds are found to suffer the axial elongation ratio δ of about 3 and 2.9% along the z-axis, meanwhile, the planar bond lengths may experience variation ratio τ (≈3.8 and 1%) along x- and y-axis for Cu2+ center in (NH4)2Zn(SO4)2·6H2O and Rb2Zn(SO4)2·6H2O, respectively. The theoretical results show good agreement with the observed values.

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