Explanation of the g-factors and Hyperfine Structure Constants of Co2+ in Tetragonal K2ZnF4

2000 ◽  
Vol 55 (5) ◽  
pp. 539-544 ◽  
Author(s):  
Wen-Chen Zheng ◽  
Shao-Yi Wu
Keyword(s):  
Hyperfine Structure ◽  
Configuration Interaction ◽  
Structural Parameters ◽  
Cluster Approach ◽  
Epr Parameters ◽  
Structure Constants ◽  
The Relationship ◽  
Good Agreement ◽  
G Factors

Abstract The formulas of the g-factors gII , g┴ and the hyperfine structure constants AII.A┴ for 3d7 ions in tetragonal octahedral crystals are established from a cluster approach. Differing from previous formulas, in these formulas the role of configuration interaction (CI)-and covalency (CO)-effects is considered, and the parameters related to both effects are obtained from the optical spectra and the structural parameters of the studied crystal. From these formulas, the EPR parameters gi and Ai for K2 ZnF4 :Co2+ are calculated. The results show good agreement with the observed values. The contributions to the EPR parameters gi and Ai, from the CI and CO effects, and the relationship between the sign of Δg(=g┴ - gII) and the tetragonal distortion (elongated or compressed) of the ligand octahedron are discussed

Studies of the g Factors and the Hyperfine Structure Constants for the Octahedral Interstitial Mn2+ and Cr+ Impurities in Silicon

2013 ◽  
Vol 68 (5) ◽  
pp. 337-342 ◽  
Author(s):  
Bo-Tao Song ◽  
Shao-Yi Wu ◽  
Zhi-Hong Zhang ◽  
Li-Li Li
Keyword(s):  
Experimental Data ◽  
Charge Transfer ◽  
Hyperfine Structure ◽  
Crystal Field ◽  
Structure Constant ◽  
Cluster Approach ◽  
Hyperfine Structure Constant ◽  
Structure Constants ◽  
Good Agreement ◽  
G Factors

The g factors and the hyperfine structure constants for the octahedral interstitial Mn2+ and Cr+ impurities in silicon are theoretically studied using the perturbation formulas of these parameters for an octahedral 3d5 cluster. In the calculations, both the crystal-field and charge transfer contributions are taken into account in a uniform way, and the related molecular orbital coefficients are quantitatively determined from the cluster approach. The theoretical g factors and the hyperfine structure constants are in good agreement with the experimental data. The charge transfer contribution to the g-shift (≈g-gs, where gs ≈ 2:0023 is the spin only value) is opposite (positive) in sign and about 51% - 116% in magnitude as compared with the crystal-field one for Mn2+ and Cr+, respectively. Nevertheless, the charge transfer contribution to the hyperfine structure constant has the same sign and about 12% - 19% that of the crystal-field one. Importance of the charge transfer contribution shows the order Cr+ < Mn2+ due to increase of the impurity valence state in the same host, especially for the g factor.

Theoretical Studies of the g Factors for Co2+ in MgO and CaO Crystals

2001 ◽  
Vol 56 (3-4) ◽  
pp. 249-252 ◽  
Author(s):  
Shao-Yi Wu ◽  
Wen-Chen Zheng
Keyword(s):  
Configuration Interaction ◽  
Optical Spectra ◽  
Theoretical Studies ◽  
Cluster Approach ◽  
Experimental Values ◽  
Good Agreement ◽  
G Factors

Abstract This paper presents a cluster approach to the calculation of the g factors for 3d7 ions in cubic oc­ tahedral crystals, in which the parameters related to the configuration interaction and the covalency reduction effects are obtained from optical spectra of the studied crystals, and so no adjustable parameters are applied. From the approach, the g factors for MgO:Co2+ and CaO:Co2+ are cal­culated. The calculated results show good agreement with the observed values. The experimental values of g 4.333 for CaO:Co2+ are also explained.

Theoretical Studies of the EPR g Factors and the Hyperfine Structure Constants of Cr3+ in MgS and SrS

2003 ◽  
Vol 58 (9-10) ◽  
pp. 503-506
Author(s):  
Shao-Yi Wu ◽  
Xiu-Ying Gao ◽  
Wei-Zi Yan
Keyword(s):  
Hyperfine Structure ◽  
Coupling Coefficient ◽  
Structure Constant ◽  
Theoretical Studies ◽  
Spin Orbit ◽  
Cluster Approach ◽  
Hyperfine Structure Constant ◽  
Structure Constants ◽  
G Factors

The EPR g factors and the hyperfine structure constant A factors for Cr3+ in MgS and SrS are theoretically studied by using the two-spin-orbit (S.O.)-coupling-coefficient formulas for a 3d3 ion in octahedra based on the cluster approach. In these formulas, both the contributions due to the S.O. coupling coefficient of the central 3d3 ion and that of ligands are taken into account. Based on these studies, the g and A factors of Cr3+ in both MgS and SrS are satisfactorily explained. The results are discussed.

Theoretical Investigations of the Spin Hamiltonian Parameters and the Local Structure of a Trigonal Co2+ Center in Bi4Ge3O12

2004 ◽  
Vol 59 (9) ◽  
pp. 563-567
Author(s):  
Shao-Yi Wu ◽  
Hui-Ning Dongb
Keyword(s):  
Hyperfine Structure ◽  
Local Structure ◽  
Reasonable Agreement ◽  
Spin Hamiltonian ◽  
Cluster Approach ◽  
Trigonal Symmetry ◽  
Theoretical Investigations ◽  
Structure Constants ◽  
Hamiltonian Parameters ◽  
G Factors

The spin Hamiltonian parameters anisotropic g factors g||, g⊥ and hyperfine structure constants A||and A⊥, as well as the local structure of the trigonal Co2+ center in Bi4Ge3O12 (BGO) are theoreticallyinvestigated by the perturbation formulas of the spin Hamiltonian parameters for a 3d7 ion intrigonal symmetry, based on the cluster approach. It is found that the impurity Co2+ substituting thehost Bi3+ undergoes an off-center displacement ΔZ(≈ −0.132 Å ) away from the center of the oxygenoctahedron along the C3 axis. The spin Hamiltonian parameters based on the above displacementshow reasonable agreement with the observed values. The results are discussed.

INVESTIGATIONS ON THE LOCAL STRUCTURE AND THE EPR PARAMETERS FORCu2+-DOPEDGaN

2008 ◽  
Vol 22 (18) ◽  
pp. 1739-1747 ◽  
Author(s):  
LI-HUA WEI ◽  
SHAO-YI WU ◽  
ZHI-HONG ZHANG ◽  
HUI WANG ◽  
XUE-FENG WANG
Keyword(s):  
Experimental Data ◽  
Local Structure ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Cluster Approach ◽  
Ligand Orbital ◽  
Epr Parameters ◽  
Structure Constants ◽  
Slight Displacement ◽  
Good Agreement

The local structure and the EPR parameters (g factors and the hyperfine structure constants) for Cu2+in GaN are theoretically studied from the perturbation formulas of these parameters for a 3d9ion in trigonally distorted tetrahedra. In these formulas, the ligand orbital and spin-orbit coupling contributions are taken into account from the cluster approach, in view of the strong covalency effect of the system. Based on the studies, the impurity Cu2+is found not to occupy exactly the host Ga3+site but to suffer a slight displacement (≈ 0.004 Å ) towards the ligand triangle along C3axis due to charge and size mismatching substitution. The theoretical EPR parameters show good agreement with the experimental data. The validity of the impurity displacement is also discussed.

scholarly journals Studies Of The Epr G Factors And Hyperfine Structure Constants For Yb3+ Ions In Single Crystals Of Zircon-Structure Orthophosphates

2003 ◽  
Vol 58 (7-8) ◽  
pp. 434-438 ◽  
Author(s):  
Hui-Ning Dong ◽  
Wen-Chen Zheng ◽  
Shao-Yi Wu ◽  
Sheng Tang
Keyword(s):  
Hyperfine Structure ◽  
Crystal Field ◽  
Lattice Relaxation ◽  
Superposition Model ◽  
Zircon Structure ◽  
Local Lattice ◽  
Epr Parameters ◽  
Structure Constants ◽  
Zircon Type ◽  
G Factors

The EPR g factors g|| and g⊥ of Yb3+ and the hyperfine structure constants A|| and A⊥ of 171Yb3+ and 173Yb3+ in crystals of the zircon-structure orthophosphates YPO4, LuPO4, and ScPO4 are calculated from the calculation formulas of the EPR parameters for a 4f13 ion in tetragonal symmetry. In these formulas, the contributions to the EPR parameters from the J-mixing between the ground 2F7/2 and excited 2F5/2 states, the admixtures between the lowest Kramers doublet Γγ and the other 6 Kramers doublets (or irreducible representations) via the crystal-field and orbital angular momentum (or hyperfine structure) interactions and the covalency reduction effect are included. The calculated values agree with the observed ones. In the calculations, the superposition model is used to estimate the crystal-field parameters. It is found intrinsic parameters Ā(R0) that the superposition model with the same R0 for Yb3+ in various zircon-type compounds obtained by considering local lattice relaxation are not scattered as those obtained by using the structural data of pure zircon-type compounds. It appears that, in order to obtain suitable superposition model parameters, the local lattice relaxation should be taken in to account.

Theoretical Studies of the Spin Hamiltonian Parameters for Fe0 and Mn– in Silicon Center

2013 ◽  
Vol 634-638 ◽  
pp. 2518-2522
Author(s):  
Min Quan Kuang ◽  
Shao Yi Wu ◽  
Bo Tao Song ◽  
Xian Fen Hu
Keyword(s):  
Experimental Data ◽  
Hyperfine Structure ◽  
Theoretical Studies ◽  
Spin Hamiltonian ◽  
Cluster Approach ◽  
Valence States ◽  
Structure Constants ◽  
Hamiltonian Parameters ◽  
Theoretical Results ◽  
Good Agreement

The spin Hamiltonian parameters (g factors and the hyperfine structure constants) for the octahedral interstitial Fe0and Mn in silicon are theoretically investigated using the perturbation formulas of these parameters for a 3d8ion under octahedral environments based on the cluster approach. The theoretical results show good agreement with the experimental data, and the ligand contributions should be considered due to the strong covalency of the systems. The interstitial occupation of the above novel 3d8impurities of rare valence states in silicon is discussed.

Investigations of the spin Hamiltonian parameters for the cubic Mn2+ centers in ZnX (X = S, Se, Te) and CdTe

2010 ◽  
Vol 88 (5) ◽  
pp. 301-306 ◽  
Author(s):  
Xue-Feng Wang ◽  
Shao-Yi Wu ◽  
Li-Li Li ◽  
Shan-Xiang Zhang
Keyword(s):  
Charge Transfer ◽  
Hyperfine Structure ◽  
Crystal Field ◽  
Pure Spin ◽  
Spin Orbit Coupling ◽  
Spin Hamiltonian ◽  
Structure Constants ◽  
Hamiltonian Parameters ◽  
Good Agreement ◽  
G Factors

The spin Hamiltonian parameters (g factors and the hyperfine structure constants) for the cubic Mn2+ centers in ZnX (X = S, Se, Te) and CdTe are investigated theoretically using the perturbation formulas of these parameters for a tetrahedral 3d5 cluster containing both the crystal-field and charge-transfer contributions. The relevant molecular orbital coefficients are uniformly determined from the cluster approach, and the calculated spin Hamiltonian parameters are in good agreement with the observed values. The g-shifts of the g factors related to the pure spin value gs (≈ 2.0023) arising from the charge transfer contributions are opposite (positive) in sign and much larger in magnitude than those from the crystal field contributions. On the other hand, the contributions from the charge-transfer mechanism to the hyperfine structure constants are the same in sign and about 20%–30% in magnitude of those from the crystal-field mechanism. The importance of the charge transfer contributions increases significantly with the increase of the covalency and the spin–orbit coupling coefficient of the ligand, i.e., S2− < Se2− < Te2−.

Investigations of the EPR Parameters and Local Structure for one Cu2+ Center in CdS

2008 ◽  
Vol 280-281 ◽  
pp. 15-20
Author(s):  
Li Hua Wei ◽  
Shao Yi Wu ◽  
Yue Xia Hu ◽  
Xue Feng Wang
Keyword(s):  
Experimental Data ◽  
Hyperfine Structure ◽  
Local Structure ◽  
Defect Structure ◽  
Reasonable Agreement ◽  
Cluster Approach ◽  
Epr Parameters ◽  
Structure Constants ◽  
Theoretical Results ◽  
The Ideal

The EPR g factors g// and g and the hyperfine structure constants for one substitutional Cu2+ center in CdS are theoretically investigated from the perturbation formulas of these parameters for a 3d9 ion under trigonally distorted tetrahedra. In view of the significant covalency of the [CuS4]6 cluster, the ligand contributions are taken into account on the basis of the cluster approach. According to the calculations, the impurity Cu2+ is found not to occupy exactly the ideal Cd2+ site but to suffer a small inward displacement 0.12 Å toward the ligand triangle along C3 axis. The theoretical results by considering the above impurity displacement show reasonable agreement with the experimental data. The defect structure of this Cu2+ center is also discussed.

scholarly journals Defect Model of a Tetragonal Sm3+ Center Found from EPR Measurements in CaF2 and SrF2 Crystals

2003 ◽  
Vol 58 (5-6) ◽  
pp. 373-375
Author(s):  
Wen-Chen Zheng ◽  
Hui-Ning Dong ◽  
Shao-Yi Wu ◽  
Sheng Tang
Keyword(s):  
Hyperfine Structure ◽  
Crystal Field ◽  
Selective Excitation ◽  
Defect Model ◽  
Free Ion ◽  
Epr Parameters ◽  
Structure Constants ◽  
Epr Measurements ◽  
Crystal Field Parameters ◽  
G Factors

The EPR parameters (g factors g∥, g⊥ and hyperfine structure constants A∥, A⊥) of a tetragonal(C4v) Sm3+ center in CaF2 and SrF2 crystals are calculated by considering the crystal-field Jmixingamong the ground 6H5/2, the first excited 6H7/2 and second excited 6H9/2 state multiplets.In the calculations the free-ion and crystal-field parameters of the tetragonal Sm3+-F− centerobtained from polarized laser-selective excitation spectroscopy are used. The calculated resultssuggest that the tetragonal Sm3+-F− center is the Sm3+ center found by later EPR measurements.The g factors g∥, g⊥ and hyperfine structure constants A∥, A⊥ of this EPR center are satisfactorilyexplained.

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