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1

Calculation of Optical and Spin-Hamiltonian Parameters for Mn^{4+} Doped in LiGa_{5}O_{8}

100%

Ciresan M., Stanciu M., Avram N.

Acta Physica Polonica A

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2009

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vol. 116

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issue 4

547-549

EN

The aim of this paper is to investigate, from theoretical point of view, the optical spectra and EPR (g-factors) parameters for Mn^{4+}:LiGa_{5}O_{8}. The optical energy levels scheme has been obtained by the diagonalization of the Hamiltonian of the system, using all 50 wave functions of the LS terms of 3d^{3} electron configuration. The crystal field parameters have been obtained in the exchange charge model of crystal field, taking into account the structure of the host matrix and effects of the covalent bond formation between the Mn^{4+} with O^{2-}. The satisfactory agreement with experimental data is obtained.

2

Crystal Field Analysis of Cr^{3+} Doped SrAl_{2}O_{4} Spinel

100%

Stanciu M., Ciresan M., Avram N.

Acta Physica Polonica A

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2009

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vol. 116

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issue 4

544-546

EN

The present work is devoted to the crystal field analysis of trivalent chromium doped in SrAl_{2}O_{4} spinel in the frame of the exchange charge model of crystal field. Using the shell model and pair approximation, we optimize the geometric structure of the crystal. The approach enables the modeling of the crystal field parameters and thus calculates the energy level scheme of Cr^{3+} ions in spinel SrAl_{2}O_{4}. The obtained results are compared with experimental data and discussed.

3

Angular Distortion around Cr^{3+} Ions Doped Diammonium Hexaaqua Magnesium Sulphate Single Crystal

100%

Ciresan M., Vaida M., Avram N.

Acta Physica Polonica A

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2007

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vol. 112

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issue 5

835-839

EN

The aim of the present study is to explain the local distortion around Cr^{3+} ions doped in the title crystal using the latest experimental data regarding optical and EPR spectra. We calculated g_ǁ, g_⊥, and D spin-Hamiltonian parameter as function of angle between the C_3 axis and metal-ligand chemical bond in local distorted octahedral cluster [CrO_6]^{9-} formed after doped crystal. The method is based on the single spin-orbit coupling parameter model, in the cluster approach using Macfarlane high order perturbation formulae. The results compared with experimental data give a reasonable agreement.

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3 Acta Physica Polonica A

2 2009

1 2007

3 Avram N.

3 Ciresan M.

2 Stanciu M.

1 Vaida M.

Calculation of Optical and Spin-Hamiltonian Parameters for Mn^{4+} Doped in LiGa_{5}O_{8}

Crystal Field Analysis of Cr^{3+} Doped SrAl_{2}O_{4} Spinel

Angular Distortion around Cr^{3+} Ions Doped Diammonium Hexaaqua Magnesium Sulphate Single Crystal