Calculation of the EPR Parameters and the Local Structure for Fe+ on the Zn2+ Site of ZnSiP2

2004 ◽  
Vol 59 (11) ◽  
pp. 769-772
Author(s):  
Shao-Yi Wu ◽  
Wang-He Wei ◽  
Hui-Ning Dong
Keyword(s):  
Local Structure ◽  
Impurity Center ◽  
High Order ◽  
Order Perturbation ◽  
Zero Field ◽  
Cluster Approach ◽  
Zero Field Splitting ◽  
Epr Parameters ◽  
Fourfold Axis ◽  
Metal Ligand

The zero-field splitting D, g factors gII and g⊥ and the local structure near Fe+ on the Zn2+ site of ZnSiP2 are calculated from high-order perturbation formulas of the EPR parameters for a 3d7 ion in tetragonally distorted tetrahedra based on the cluster approach. According to these studies, we find that the impurity-ligand bonding angle αloc related to the fourfold axis is about 58.05◦ in the studied Fe+ impurity center, which is larger than the metal-ligand bonding angle αh(≈ 56.65◦) in pure ZnSiP2. The EPR parameters based on the above angle αloc agree well with the observed values. The errors of the results are analyzed

scholarly journals Theoretical Studies of the EPR Parameters and the Local Structure of the Tetragonal Fe+ Center in KTaO3

2005 ◽  
Vol 60 (1-2) ◽  
pp. 101-105
Author(s):  
Shao-Yi Wu ◽  
Hui-Ning Dong ◽  
Xiu-Ying Gao
Keyword(s):  
Local Structure ◽  
Impurity Center ◽  
Tetragonal Distortion ◽  
Zero Field ◽  
Theoretical Studies ◽  
Zero Field Splitting ◽  
Quadrupole Shift ◽  
Epr Parameters ◽  
Nuclear Quadrupole ◽  
G Factors

The EPR parameters (zero-field splitting D and g factors g‖ and g⊥) and the local structure for the tetragonal Fe+ center in KTaO3 are theoretically studied by using the perturbation formulas of the EPR parameters for a 3d7 ion in tetragonally distorted dodecahedra. Based on these studies, we find that the impurity Fe+ may not locate on the regular dodecahedral K+ site but suffer a large off-center displacement ΔZ (≈ 0.43 Å) along one of the 100 〈or C4〉 axes, which is responsible for the large tetragonal distortion of the impurity center. The displacement ΔZ obtained in this work is comparable with that (≈ 0.46 Å ) of a similar monovalent Li+ on K+ site of KTaO3 obtained from the nuclear quadrupole shift and can be regarded as reasonable. The calculated g factors, particularly the anisotropy Δg (= Kg⊥ −g‖) based on the above displacement, agree with the observed values.

EPR Parameters and Local Atom-position Parameters for Co2+ Ions in CdS and CdSe Semiconductors

2004 ◽  
Vol 59 (11) ◽  
pp. 783-786 ◽  
Author(s):  
Wen-Chen Zheng ◽  
Xiao-Xuan Wu ◽  
Yang Mei ◽  
Jian Zi
Keyword(s):  
Coupling Parameter ◽  
Zero Field ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Cluster Approach ◽  
Zero Field Splitting ◽  
Trigonal Symmetry ◽  
Epr Parameters ◽  
Impurity Centers ◽  
Atom Position

The EPR parameters (zero-field splitting D and g factors gII, g⊥) of Co2+ ions in CdS and CdSe semiconductors are calculated from the high-order perturbation formulas based on the cluster approach for a 3d7 ion in trigonal symmetry. These formulas include the contribution to the EPR parameters from both the spin-orbit coupling parameter of the 3d7 ion and that of the ligand. From the calculations, the local atom-position parameters u (which are different from the corresponding values in the host crystals) for the Co2+ impurity centers in both semiconductors are estimated. The results are discussed

Studies of EPR Parameters and Local Structure for Cr3+ in NaInS2 Crystal

2005 ◽  
Vol 60 (1-2) ◽  
pp. 91-94
Author(s):  
Yang Mei ◽  
Wen-Chen Zheng ◽  
Xiao-Xuan Wu ◽  
Qing Zhoua
Keyword(s):  
Local Structure ◽  
Coupling Parameter ◽  
Orbit Coupling ◽  
Zero Field ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Zero Field Splitting ◽  
Field Splitting ◽  
Epr Parameters ◽  
Local Angle

The EPR parameters (zero-field splitting D and g factors g‖, g⊥) of Cr3+ in a NaInS2 crystal are calculated from high-order perturbation formulas based on the two spin-orbit coupling parameter model for the EPR parameters of 3d3 ions in trigonal octahedral sites. In the calculations, both the contribution to EPR parameters from the spin-orbit coupling parameter of the central 3d3 ion and that of ligands are considered. From the calculations it is found that, to explain reasonably the EPR parameters, the local structure (in particular the local trigonal distortion angle θ ) in the vicinity of the Cr3+ impurity is different from the corresponding structure in the host crystal. The change of the local angle θ with temperature is also obtained from the temperature dependence of zero-field splitting. The results are discussed.

Studies of Zero-field Splitting and its Pressure and Stress Dependence for Ni2+ in La2Mg3(NO3)12 · 24 H2O Crystal

2001 ◽  
Vol 56 (12) ◽  
pp. 855-858
Author(s):  
Wen-Chen Zheng ◽  
Shao-Yi Wu ◽  
Hui-Ning Dong
Keyword(s):  
Uniaxial Stress ◽  
High Order ◽  
Order Perturbation ◽  
Zero Field ◽  
Stress Dependence ◽  
Zero Field Splitting ◽  
Field Splitting ◽  
Trigonal Distortion

AbstractBy using the high-order perturbation formulas, the g factors g||and g⊥, the zero-field splittings D and the pressure and uniaxial stress dependences of zero-field splitting are studied for Ni2+ ions in both Mg + sites of La2Mg3(NO3)12 • 24 H2O crystal. It is found that the local trigonal distortion angles ßiof the two Ni + centers are only slightly different from the corresponding host ones, but the local angular compressibilities under pressure and stress for both Ni centers are quite different not only from the corresponding host ones, but also from each other.

Investigations of the Defect Structures and EPR Parameters for the Tetragonal and Cubic Ni2+ Centers in AgX (X=Cl, Br)

2008 ◽  
Vol 272 ◽  
pp. 117-122
Author(s):  
Zhi Hong Zhang ◽  
Shao Yi Wu ◽  
Li Hua Wei ◽  
Yue Xia Hu
Keyword(s):  
Experimental Data ◽  
Reasonable Agreement ◽  
Zero Field ◽  
Nearest Neighbour ◽  
Defect Structures ◽  
Cluster Approach ◽  
Zero Field Splitting ◽  
Paramagnetic Resonance ◽  
Epr Parameters ◽  
Electron Paramagnetic

The defect structures and the electron paramagnetic resonance (EPR) parameters zero-field splitting and the g factors for the tetragonal and cubic Ni2+ centers in AgX (X=Cl, Br) are theoretically studied from the perturbation formulas of these parameters for a 3d8 ion in tetragonal and cubic octahedra. In these formulas, the ligand s-orbital contributions, which were usually neglected in the previous studies, are taken into account based on the cluster approach. The ligand X− intervening in the Ni2+ and the next nearest neighbour Ag+ vacancy VAg is suggested to suffer a small inward displacement (≈ 0.11 or 0.15Å for AgCl or AgBr, respectively) towards Ni2+ along the [100] (or C4) axis. The calculated EPR parameters based on the above defect structures show reasonable agreement with the experimental data.

Theoretical Investigations of the Local Structure and the EPR Parameters of Mn4+ in LiF:U:Mn Crystal

2003 ◽  
Vol 58 (12) ◽  
pp. 672-676
Author(s):  
Shao-Yi Wu ◽  
Wang-He Wei ◽  
Hui-Ning Dong
Keyword(s):  
Hyperfine Structure ◽  
Local Structure ◽  
Electrostatic Attraction ◽  
Zero Field ◽  
Zero Field Splitting ◽  
Field Splitting ◽  
Theoretical Investigations ◽  
Distorted Octahedra ◽  
Epr Parameters ◽  
Structure Constants

The local structure and the EPR parameters (zero-field splitting D, g factors g‖ and g⊥ and hyperfine structure constants A‖ and A⊥) ofMn4+ in LiF:U:Mn crystal have theoretically been investigated by using the perturbation formulas of the EPR parameters for a 3d3 ion in trigonally distorted octahedra. In this trigonal Mn4+ center, three U6+ ions locate on (1,1,0), (1,0,1) and (0,1,1) sites, each surrounded by six O2− ions. Thus, the studied system is characterized as the Mn4+ associated with one host F− triangle, one O2− triangle and an additional equivalent F’− triangle containing the three U6+ ions, i.e. an [MnF3O3F’3]8− cluster. The central Mn4+ impurity is found to shift towards the oxygen triangle along the C3 (or [111]) axis by an amount ΔZ (≈ 0.29 Å) due to the strong electrostatic attraction between the Mn4+ and the oxygen triangle (and also the additional equivalent F’− triangle), which increases the trigonal distortion of the Mn4+ center considerably. The calculated EPR parameters based on the above displacement ΔZ agree reasonably with the observed values.

Theoretical Study of the Local Lattice Distortion at the Trigonal Cr3+ Center in BiI3

2006 ◽  
Vol 61 (1-2) ◽  
pp. 78-82 ◽  
Author(s):  
Shao-Yi Wu ◽  
Xiu-Ying Gao ◽  
Hui-Ning Dong
Keyword(s):  
Lattice Distortion ◽  
Theoretical Study ◽  
Impurity Center ◽  
Cluster Approach ◽  
Pure Crystal ◽  
Local Lattice Distortion ◽  
Trigonal Symmetry ◽  
Local Lattice ◽  
Epr Parameters ◽  
Local Angle

The local lattice distortion at the trigonal Cr3+ center in BiI3 is theoretically studied by the perturbation formulas of the EPR parameters for a 3d3 ion in trigonal symmetry, based on the cluster approach. In these formulas the contributions from the s-orbitals of the ligands, which were often ignored, are taken into account. It is found that the local angle β (between the direction of the impurityligand bonding R and the C3 axis) in the impurity center is smaller than the host angle βH in the pure crystal. The calculated EPR parameters are improved compared to those in absence of the ligand s-orbital contributions. The local lattice distortion obtained in this work is discussed.

Studies of Knight Shifts and Hyperfine Structure Constants of Tl2Ba2CuO6+y

2013 ◽  
Vol 337-338 ◽  
pp. 49-53
Author(s):  
Min Quan Kuang ◽  
Shao Yi Wu ◽  
Xian Fen Hu ◽  
Bo Tao Song
Keyword(s):  
Hyperfine Structure ◽  
Local Structure ◽  
High Order ◽  
Order Perturbation ◽  
Calculation Results ◽  
Structure Constants ◽  
Knight Shifts ◽  
Good Agreement

The Knight shifts and hyperfine structure constants of Tl2Ba2CuO6+yare theoretically studied from the high order perturbation formulas of these quantities for a tetragonally elongated octahedral 3d9cluster. The calculation results reveal good agreement with the observed values. The obvious anisotropies of the Knight shifts can be ascribed to the local tetragonal elongation of the Cu2+site. The results and the local structure of the system are discussed.

Sign in / Sign up

Export Citation Format

Share Document