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'Crystal field Theory' in keywords Facet   Publication Year 2000  [X]
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2000[X]
1Author    Shao-Yi Wu, Wen-Chen ZhengRequires cookie*
 Title    Defect Structure of Co 2+ Center in 05-LiIO 3 Crystal  
 Abstract    In this paper we establish the formulas of EPR g factors g», for 3d 7 ions in trigonal octahedral crys-tals from a cluster approach. In these formulas, the contributions from configuration interaction-and covalency-effects are considered. The parameters related to both effects can be determined from the optical spectra and the structural parameters of the studied crystal. With these formulas, the defect struc-ture of a Co 2+ center in a-LiI0 3 crystal is studied. It is found that, to reach good fits between the cal-culated and observed g», g ± , the O ions between Co 2+ and Li + vacancy (V Li) should shift away from the V u by about 0.49 A. "Hie displacement direction is consistent with those obtained for Cr 3+ , Fe 3+ , and Mn 2 centers in a-LiI0 3 crystals as well as with the expectation based on the electrostatic interac-tion model. 
  Reference    Z. Naturforsch. 55a, 828—832 (2000); received June 29 2000 
  Published    2000 
  Keywords    Electron Paramagnetic Resonance (EPR), Crystal-field Theory, Defect Structure, Co 2+, a-LiI0 3 Crystal 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0828.pdf 
 Identifier    ZNA-2000-55a-0828 
 Volume    55 
2Author    Wen-Chen Zheng, Shao-Yi WuRequires cookie*
 Title    Studies of the Local Phase-transition Behaviour for Ni + -II Centers in RbCaF 3 Crystal from EPR Data  
 Abstract    By fitting the calculated EPR g,(i = JC, y, z) factors to the observed values, the local release factor which is introduced to characterize the release (or elongation) effect of impurity-ligand bonds along the rotational axis in the cubic-to-tetragonal phase transition of ABX 3 perovskites, is obtained for the Ni + -II center in RbCaF 3 crystal. The result shows that, similar to the local rotational angle (or order param-eter) (p, the local release factor is unlike that of the host crystal. It suggests that in the doped crystal the impurity can affect the local phase transition behaviour in the vicinity of impurity ions. 
  Reference    Z. Naturforsch. 55a, 915—917 (2000); received September 12 2000 
  Published    2000 
  Keywords    Local Phase Transition Behaviour, E P R, Crystal-field Theory, Ni + ion, RbCaF 3 PACS: 6470Kb, 7630Fc, 7170Ch 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0915.pdf 
 Identifier    ZNA-2000-55a-0915 
 Volume    55