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.

INVESTIGATIONS OF THE SPIN HAMILTONIAN PARAMETERS AND THE LOCAL STRUCTURE FOR THE RHOMBICCu2+CENTER IN RUTILE

2010 ◽  
Vol 24 (22) ◽  
pp. 2357-2364 ◽  
Author(s):  
HUA-MING ZHANG ◽  
SHAO-YI WU ◽  
PEI XU ◽  
LI-LI LI
Keyword(s):  
Local Structure ◽  
Impurity Center ◽  
Angular Distortion ◽  
Spin Hamiltonian ◽  
Rhombic Distortion ◽  
Calculation Results ◽  
Jahn Teller ◽  
Jahn Teller Effect ◽  
Structure Constants ◽  
Hamiltonian Parameters

The spin Hamiltonian parameters (the anisotropic g factors and the hyperfine structure constants) and the local structure for the rhombic Cu2+center in rutile ( TiO2) are theoretically investigated using the formulas of these parameters for a 3d9ion in rhombically elongated octahedra. From the studies, the planar impurity-ligand bond angle is found to be about 5.8° larger than that for the host Ti4+site due to the Jahn–Teller effect via bending the planar Cu2+– O2-bonds, which yields much smaller rhombic distortion in the impurity center. The theoretical spin Hamiltonian parameters based on the above local angular distortion show good agreement with the experimental data, and the improvement of the calculation results are also achieved as compared with those of the previous works.

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 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.

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.

Studies of the Spin Hamiltonian Parameters for NiX2 and CdX2:Ni2+ (X=Cl, Br)

2009 ◽  
Vol 282 ◽  
pp. 25-30
Author(s):  
Zhi Hong Zhang ◽  
Shao Yi Wu ◽  
Xue Feng Wang ◽  
Yue Xia Hu
Keyword(s):  
Zero Field ◽  
Spin Hamiltonian ◽  
Zero Field Splitting ◽  
Local Structures ◽  
Ligand Orbital ◽  
Distorted Octahedra ◽  
Lattice Distortions ◽  
Hamiltonian Parameters ◽  
Ligand Bond ◽  
G Factors

The spin Hamiltonian parameters (zero-field splitting D and the g factors) for NiX2 and CdX2:Ni2+ (X=Cl, Br) are quantitatively investigated from the perturbation formulas of these parameters for a 3d8 ion in trigonally distorted octahedra based on the cluster approach. In the calculations, the trigonal field parameters  and ′ are determined from the superposition model and the local structures of Ni2+ in the halides. The theoretical g factors show reasonable agreement with the observed values, and the experimental D for CdX2:Ni2+ are also interpreted by considering suitable lattice distortions (angular decreases) in the impurity-ligand bond angles related to the C3 axis due to the size mismatching substitution. The contributions from the ligand orbital and spin-orbit coupling interactions are important and should be taken into account.

STUDIES ON THE LOCAL STRUCTURE AND THE SPIN HAMILTONIAN PARAMETERS FOR THE TRIGONAL Mn2+ CENTER IN Bi4Ge3O12

2008 ◽  
Vol 22 (14) ◽  
pp. 1381-1387 ◽  
Author(s):  
XUE-FENG WANG ◽  
SHAO-YI WU ◽  
ZHI-HONG ZHANG ◽  
LI-HUA WEI ◽  
YUE-XIA HUA
Keyword(s):  
Hyperfine Structure ◽  
Local Structure ◽  
Zero Field ◽  
Spin Hamiltonian ◽  
Zero Field Splitting ◽  
Trigonal Symmetry ◽  
Oxygen Octahedron ◽  
Structure Constants ◽  
Hamiltonian Parameters ◽  
Good Agreement

The local structure and the spin Hamiltonian parameters (the zero-field splitting D, the g factors g//, g⊥ and the hyperfine structure constants A// and A⊥) for the trigonal Mn 2+ center in Bi 4 Ge 3 O 12 are theoretically studied from the perturbation formulas of these parameters for a 3d5 ion in trigonal symmetry. The impurity Mn 2+ replacing host Bi 3+ is not found to occupy the exact Bi 3+ site but to suffer a large off-center displacement by about 0.36 Å towards the center of the oxygen octahedron along the C3-axis due to the size and charge mismatching substitution. The calculated spin Hamiltonian parameters based on the above displacement show good agreement with the observed values. The results and the mechanism of the impurity displacement are discussed.

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.

Studies of the Axial Shift and the Spin Hamiltonian Parameters for Mn2+ in a CdS Crystal

2009 ◽  
Vol 294 ◽  
pp. 77-83
Author(s):  
Xue Feng Wang ◽  
Shao Yi Wu ◽  
Yue Xia Hu ◽  
Pei Xu
Keyword(s):  
Reasonable Agreement ◽  
Zero Field ◽  
Spin Orbit Coupling ◽  
Spin Hamiltonian ◽  
Cluster Approach ◽  
Zero Field Splitting ◽  
Ligand Orbital ◽  
Axial Shift ◽  
Structure Constants ◽  
Hamiltonian Parameters

The axial shift and the spin Hamiltonian parameters (zero-field splitting D, the g factors and the hyperfine structure constants A// and A) for Mn2+ in a CdS crystal are studied theoretically in this work. The calculations are carried out by using the perturbation formulae of these parameters for a 3d5 ion under trigonally distorted tetrahedra based upon the cluster approach, where the ligand orbital and spin-orbit coupling contributions are taken into account in a uniform way. From the studies, the impurity Mn2+ is found not to occupy the host Cd2+ site exactly but to experience a small outward shift of 0.018 Å away from the ligand triangle along the C3 axis. The above impurity axial shift leads to a much smaller trigonal distortion than the host Cd2+ site in CdS. The calculated spin Hamiltonian parameters are in reasonable agreement with the experimental data.

The studies of the spin Hamiltonian parameters and local structures for various 3d3 hexacyanometallates of paramagnetic salts with diluents

2016 ◽  
Vol 30 (27) ◽  
pp. 1650204 ◽  
Author(s):  
Hui-Ning Dong ◽  
Xu-Sheng Liu ◽  
Hong-Fei Zhou
Keyword(s):  
Crystal Field Parameter ◽  
Zero Field ◽  
Spin Hamiltonian ◽  
Cubic Crystal ◽  
Local Structures ◽  
Structures And Properties ◽  
Distorted Octahedral ◽  
Rhombic Distortion ◽  
Structure Constants ◽  
Hamiltonian Parameters

The spin Hamiltonian parameters (SHPs) ([Formula: see text] factors, hyperfine structure constants and zero-field splittings (ZFSs)) and local structures for various [Formula: see text] hexacyanometallates of paramagnetic salts K3Cr(CN)6 and K4V(CN)[Formula: see text]3H2O with the diluents K3Co(CN)6, K3Mn(CN)6 and K4Fe(CN)[Formula: see text]3H2O are theoretically investigated from the perturbation calculations of these parameters for a rhombically distorted octahedral [Formula: see text] cluster. The paramagnetic systems are found to undergo the local axial distortions [Formula: see text] [Formula: see text]0.19, −0.18 and 0.09 Å[Formula: see text] and the planar bond angle variations [Formula: see text] [Formula: see text] 3.5[Formula: see text], 5.3[Formula: see text] and 1.4[Formula: see text] for K3Cr(CN)6 with K3Co(CN)6, K3Cr(CN)6 with K3Mn(CN)6 and K4V(CN)[Formula: see text]3H2O with K4Fe(CN)[Formula: see text] 3H2O, respectively. The signs for ZFSs [Formula: see text] and [Formula: see text] are analyzed in the light of those for [Formula: see text] and the rhombic distortion angle [Formula: see text] [Formula: see text] related to an ideal octahedron. Microscopically, the magnitudes of [Formula: see text] and [Formula: see text] can be conveniently illustrated by the axial (ADD) and perpendicular distortion degrees (PDD), respectively, for the paramagnetic systems with the corresponding diluents. The local structural properties are analyzed from the relative ionic radius deviation [Formula: see text] of the equivalent diluent cation from the host paramagnetic cation, the axial and perpendicular ZFS variations [Formula: see text] and [Formula: see text] for ZFSs with the diluent related to the host, the relative deviation [Formula: see text]Dq of the cubic crystal-field parameter for the diluent related to the host. The above studies would be helpful to the investigations on synthesis, structures and properties of [Formula: see text] hexacyanometallates in paramagnetic salts.

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.

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