Theoretical Investigations of the Defect Structure for Ni3+ in ZnO

2011 ◽  
Vol 318 ◽  
pp. 41-45
Author(s):  
Zhi Hong Zhang ◽  
Shao Yi Wu ◽  
Shan Xiang Zhang
Keyword(s):  
Defect Structure ◽  
Impurity Center ◽  
Spin Hamiltonian ◽  
Theoretical Investigations ◽  
Ligand Orbital ◽  
High Valence State ◽  
Zno Crystal ◽  
Hamiltonian Parameters ◽  
Good Agreement ◽  
The Ideal

The defect structure for Ni3+ in ZnO crystal is theoretically investigated using the perturbation formulas of the spin Hamiltonian parameters for a 3d7 ion in trigonally distorted tetrahedra. In view of the significant covalency of the system due to the high valence state of Ni3+, the ligand orbital and spin-orbit coupling contributions are taken into account in a uniform way based on the cluster approach. The impurity Ni3+ is found not to occupy the ideal Zn2+ site in ZnO but to undergo the small axial displacement of about 0.044 Ǻ away from the oxygen triangle along the C3 axis. The theoretical spin Hamiltonian parameters based on the above impurity displacement show good agreement with the experimental data. The defect structure of this impurity center is compared with that for the similar Fe3+ in ZnO.

Theoretical Investigations of the Spin Hamiltonian Parameters and Defect Structure for Pt3+ in MgO

2009 ◽  
Vol 293 ◽  
pp. 71-76
Author(s):  
Yue Xia Hu ◽  
Shao Yi Wu ◽  
Xue Feng Wang ◽  
Li Li Li
Keyword(s):  
Defect Structure ◽  
Relative Elongation ◽  
Impurity Center ◽  
Spin Hamiltonian ◽  
Theoretical Investigations ◽  
Ligand Orbital ◽  
Jahn Teller ◽  
Jahn Teller Effect ◽  
Structure Constants ◽  
Hamiltonian Parameters

The spin Hamiltonian parameters (anisotropic g-factors and the hyperfine structure constants) and defect structure for Pt3+ in MgO are theoretically investigated by using the perturbation formulas of these parameters for a 5d7 ion in a tetragonally elongated octahedron. This impurity center is attributed to substitutional Pt3+ on host Mg2+ sites, and the [PtO6]9 cluster suffers a relative elongation of 0.08Å along the C4 axis due to the Jahn-Teller effect. In the calculations, the contributions arising from the ligand orbital and spin-orbit coupling interactions and the Jahn-Teller elongation are taken into account using the cluster approach. The calculated spin Hamiltonian parameters based upon the above defect structure show good agreement with the observed values.

Theoretical investigations on the spin Hamiltonian parameters and the local structure for Rh2+ in rutile

2010 ◽  
Vol 88 (1) ◽  
pp. 49-53 ◽  
Author(s):  
S. X. Zhang ◽  
S. Y. Wu ◽  
P. Xu ◽  
L. L. Li
Keyword(s):  
Local Structure ◽  
Impurity Center ◽  
Angular Distortion ◽  
Spin Hamiltonian ◽  
Theoretical Investigations ◽  
Rhombic Distortion ◽  
Ligand Orbital ◽  
Jahn Teller ◽  
Jahn Teller Effect ◽  
Hamiltonian Parameters

The spin Hamiltonian parameters, the g factors gi (i = x, y, z) and the hyperfine structure constants Ai, and the local structure for Rh2+ in rutile (TiO2) are theoretically investigated from the perturbation formulas of these parameters for a 4d7 ion under rhombically elongated octahedra. In view of the covalency, the ligand orbital and spin-orbit coupling contributions are taken into account from the cluster approach. The planar bond angle in the impurity center is found to be 7.5° larger than that of the host Ti4+ site because of the Jahn–Teller effect via bending of the planar Rh2+-O2– bonds, leading to much smaller rhombic distortion. The theoretical spin Hamiltonian parameters based on the above Jahn–Teller angular distortion show reasonable agreement with the experimental data.

Theoretical Investigations for the Defect Structure and the Spin Hamiltonian Parameters of Divalent Cobalt in LiMgPO4

2021 ◽  
Vol 1032 ◽  
pp. 108-113
Author(s):  
Xu Sheng Liu ◽  
Shao Yi Wu ◽  
Yi Mei Fan ◽  
Xing Yuan Yu
Keyword(s):  
Defect Structure ◽  
Spin Hamiltonian ◽  
Size Mismatch ◽  
Local Structures ◽  
Distorted Octahedral ◽  
Theoretical Investigations ◽  
Divalent Cobalt ◽  
Structure Constants ◽  
Relative Compression ◽  
Hamiltonian Parameters

The spin Hamiltonian parameters (SHPs, g factors and hyperfine structure constants) defect structure for LiMgPO4 doped with 0.1% Co2+ at 4.2 K are theoretically investigated from the perturbation formulas of the SHPs for a rhombically distorted octahedral 3d7 cluster. The impurity Co2+ on host Mg2+ site is found to suffer the larger axial relative compression ratio ρ (≈ 0.76%) and the planar angular variation Δφ (≈ 6.64°) related to the host oxygen octahedron due to size mismatch. The calculated SHPs based on the above defect structure show good agreement with the measured results. Present study can be helpful to the preparation and characterization for the local structures for transition-metal impurities in lithium-magnesium phosphate, which may is helpful to search for the phosphor materials with better dosimetric characteristics.

Studies on the Local Angular Distortion and Spin Hamiltonian Parameters for the Trigonal Co2+ Center in MgCl2

2014 ◽  
Vol 69 (10-11) ◽  
pp. 562-568 ◽  
Author(s):  
Xian-Fen Hu ◽  
Shao-Yi Wu ◽  
Min-Quan Kuang ◽  
Guo-Liang Li
Keyword(s):  
Bond Angle ◽  
Angular Distortion ◽  
Spin Hamiltonian ◽  
Distorted Octahedral ◽  
Ligand Orbital ◽  
Host Metal ◽  
Structure Constants ◽  
Hamiltonian Parameters ◽  
Good Agreement ◽  
Ligand Bond

AbstractThe local angular distortion and spin Hamiltonian parameters (g factors g||, g⊥ and the hyperfine structure constants) for the trigonal Co2+ center in MgCl2 are theoretically studied by diagonalizing the 6×6 energy matrix of ground 4T1 state for a trigonally distorted octahedral 3d7 cluster. Based on the cluster approach, the contributions from the admixtures of various J (= 1/2;3/2;5/2) states and the ligand orbital and spin-orbit coupling interactions are taken into account in a uniform way. The local impurity-ligand bond angle in the Co2+ center is found to be about 3.44° larger than the host metal-ligand bond angle in the pure crystal due to substitution of smaller Mg2+ by bigger Co2+, inducing a further compressed ligand octahedron. The calculated spin Hamiltonian parameters using the above local angular distortion are in good agreement with the experimental data. The present studies on the local structure and the spin Hamiltonian parameters for Co2+ in MgCl2 are tentatively extended to a more general case by comparing the relevant impurity behaviours for Co2+ in various trigonal environments.

Studies on the Local Structure and the Spin Hamiltonian Parameters for Co2+ in CaTiO3

2008 ◽  
Vol 278 ◽  
pp. 55-62 ◽  
Author(s):  
Guang Duo Lu ◽  
Shao Yi Wu ◽  
Hua Ming Zhang ◽  
Li Hua Wei
Keyword(s):  
Local Structure ◽  
Lattice Distortion ◽  
Impurity Center ◽  
Orthorhombic Symmetry ◽  
Spin Hamiltonian ◽  
Orthorhombic Distortion ◽  
Local Lattice Distortion ◽  
Local Lattice ◽  
Crystal Field Parameters ◽  
Hamiltonian Parameters

The local structure and the spin Hamiltonian parameters g factors gi (i =x, y and z) and the hyperfine structure constants Ai for Co2+ in orthorhombic CaTiO3 are theoretically investigated from diagonalization of 6 × 6 energy matrix within the 4T1 ground state for a 3d7 ion in orthorhombic symmetry. In the calculations, the contributions from the admixtures of various J states (J=1/2, 3/2, 5/2), the ligand orbitals and spin-orbit coupling and the fourth-order orthorhombic field parameter, which were usually neglected in the previous works, are taken into account. The crystal-field parameters are determined from the superposition model in consideration of the suitable lattice distortion due to the charge and size mismatching substitution of Ti4+ by Co2+. Based on the studies, the bond lengths R1 and R2 in the xy plane are estimated to suffer the relative alternation R ≈ 5.4%, yielding more significant orthorhombic distortion in the impurity center as compared with that for the host Ti4+ site in pure crystal. The calculation results based on the above local lattice distortion show reasonable agreement with the observed values. The various contributions to the spin Hamiltonian parameters are discussed. Present studies may theoretically verify that the impurity Co2+ occupies the 6-fold coordinated Ti4+ site rather than the 12-fold coordinated Ca2+ site, associated with the enhanced orthorhombic distortion due to the mismatching substitution.

Theoretical Investigations Of The Spin Hamiltonian Parameters Of Zrsio4:Np4+

2004 ◽  
Vol 59 (7-8) ◽  
pp. 471-475
Author(s):  
Shao-Yi Wu ◽  
Hui-Ning Dong
Keyword(s):  
Experimental Data ◽  
Energy Levels ◽  
Structural Data ◽  
Superposition Model ◽  
Spin Hamiltonian ◽  
Theoretical Investigations ◽  
Structure Constants ◽  
Crystal Field Parameters ◽  
Hamiltonian Parameters ◽  
Theoretical Results

In this work, the spin Hamiltonian (SH) parameters g|| and g⊥, and the hyperfine structure constants A|| and A⊥ for ZrSiO4:Np4+ are investigated on the basis of the perturbation formulas of these parameters for a 5f3 ion in tetragonal (D2d) symmetry. In these formulas, the contributions to the SH parameters from the second-order perturbation terms, the admixtures of various energy levels and the covalency effect are taken into account. The related crystal-field parameters are calculated from the superposition model and the local structural data of the Zr4+ site occupied by the impurity Np4+. The calculated SH parameters agree reasonably with the experimental data. The validity of the theoretical results is discussed.

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