Theoretical Studies of EPR Parameters and Microstructure of the Rhombic Co2+-VAg Centre in AgCl

Zeitschrift Für Naturforschung A

Yang

2010

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The spin-Hamiltonian (SH) parameters (g factors g , g ⊥ and hyperfine structure constants A , A ⊥ ) for the Co 2+ ion in the tetragonal Zn 2+ site of a Ba 2 ZnF 6 crystal are calculated from the secondorder perturbation formulas based on the cluster approach for the SH parameters of 3d 7 ions in tetragonal symmetry with the effective spin S = 1/2. In the calculations, a reduction factor due to the dynamical Jahn-Teller effect is used. The calculated results are in reasonable agreement with the experimental values, suggesting that the dynamical Jahn-Teller effect should be considered here. The defect structure of the Co 2+ center in Ba 2 ZnF 6 :Co 2+ is also obtained from the calculations. The results are discussed.

Section: Discussionmentioning

confidence: 99%

A Study of Spin-Hamiltonian Parameters and Defect Structure for Co²⁺ Ion in the Tetragonal Zn²⁺ Site of Ba₂ZnF₆ Crystal

Lia

Zeitschrift Für Naturforschung A

Yang

2010

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“…Thus from the cluster approach, the microscopic formulas of g factors for 3d 7 (Co 2+ ) ions in rhombic octahedral clusters are derived by using the following perturbation method [11]: [16]. The normalization factors N and the orbital mixing coefficients can be estimated from a semiempirical LCAO method [10,13,14]. According to this method we have the normalization condition N (1 ; 2 S dp ( ) + 2 ) = 1 (5) and the approximate relationship f N 2 [1 + 2 S 2 dp ( ) ; 2 S dp ( )] where S dp ( ) are the group overlap integrals.…”

Section: Calculationmentioning

confidence: 99%

“…where the power-law exponents t 2 3 and t 4 5 because of the ionic nature of bonds [10,22]. A 2 (R 0 ) and A 4 (R 0 ) are the intrinsic parameters with the reference distance R 0 (= R).…”

Section: +mentioning

confidence: 99%

“…A 2 (R 0 ) and A 4 (R 0 ) are the intrinsic parameters with the reference distance R 0 (= R). For the 3d n octahedral cluster, A 4 (R 0 ) (3/4)D q [10,22]. Since the ratio A 2 (R 0 ) / A 4 (R 0 ) is in the range of 9 -12 for 3d n ions in many crystals [10,23,24], we take A 2 (R 0 ) 9.2 A 4 (R 0 ) here.…”

Section: +mentioning

confidence: 99%

“…For overcoming the weakness of [10], we present now a cluster approach to the calculation of g i for 3d 7 (Co 2+ ) in rhombic octahedra. In these formulas, the contributions of the covalency effect, the configuration interaction and the rhombic field are considered and the parameters related to the three important contributions can be estimated from the optical spectra and the structural data of the crystal under study.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Studies of EPR g-factors on Rutile (TiO₂) with Co²⁺ Ion

Zeitschrift Für Naturforschung A

2002

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The anisotropic g-factors g X , g Y , and g Z for Co 2+ in rutile crystal are studied from the secondorder perturbation formulas based on the cluster approach. In the studies, the contributions due to covalency effects, the configuration interaction and the rhombic crystal field are taken into account. The calculated values are close to the observed ones. The small discrepancy between calculation and experiment is discussed.

Studies of the EPR Parameters gi and Ai for Co2+ in the Octahedral Sites of Y3Al5O12 and Y3Ga5O12 Crystals

2001

phys. stat. sol. (b)

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The perturbation formulas of EPR g factors g || , g ? and hyperfine structure constants A || , A ? for the trigonal octahedral 3d 7 cluster are derived considering not only the configuration interaction effect due to the admixture among ground and excited states, but also the covalency effect due to the admixture between the d electrons of the 3d 7 ion and the p electrons of ligands. In these formulas, the parameters related to both effects and the trigonal field parameters are estimated from the optical spectra and the structural parameters of the studied system. According to these formulas, the EPR parameters g || , g ? , A || and A ? for Co 2þ in the octahedral sites of Y 3 Al 5 O 12 and Y 3 Ga 5 O 12 garnets are satisfactorily explained from the optical spectra and the structure data. The role of the covalency effect is discussed.