The influence of local structure and intrinsic crystal-field on the EPR parameters for Nd3+ ions in Bi4Ge3O12 crystal

2021 ◽  
Vol 1198 ◽  
pp. 113181
Author(s):  
Rui-Peng Chai ◽  
Dan-Hui Hao ◽  
Liang Liang ◽  
Long Li ◽  
Dang-Li Gao ◽  
...  
Keyword(s):  
Crystal Field ◽  
Local Structure ◽  
Epr Parameters

scholarly journals Investigations on the local structure and the EPR parameters for the tetragonal Cu2+center in ZnSeF6·6H2O crystal

2016 ◽  
Vol 94 (5) ◽  
pp. 507-510 ◽  
Author(s):  
Chao-Ying Li
Keyword(s):  
Crystal Field ◽  
Local Structure ◽  
Relative Elongation ◽  
Paramagnetic Resonance ◽  
Ligand Orbital ◽  
Jahn Teller ◽  
Jahn Teller Effect ◽  
Epr Parameters ◽  
Structure Constants ◽  
Crystal Field Parameters

The electron paramagnetic resonance (EPR) parameters (g factors g∥, g⊥and hyperfine structure constants A∥, A⊥) and the local structure of the tetragonal Cu2+center in trigonal ZnSeF6·6H2O crystal are theoretically investigated from the perturbation formulas of these parameters for a 3d9ion in tetragonally elongated octahedra. In the calculated formulas, the contributions to the EPR parameters from ligand orbital and spin–orbit coupling are included on the basis of the cluster approach in view of moderate covalency of the studied systems, the required crystal-field parameters are estimated from the superposition model, which enables correlation of the crystal-field parameters and hence the EPR parameters with the tetragonal distortion of the studied [Cu(H2O)6]2+cluster. According to the calculations, the ligand octahedra around Cu2+are suggested to suffer relative elongation τ (≈ 0.085 Å) along the [001] (or C4) axis for the tetragonal Cu2+centers in ZnSeF6·6H2O crystal, due to the Jahn–Teller effect. The results are discussed.

Studies of local structures for Cu2+ centers in M2Zn(SO4)2·6H2O (M = NH4 and Rb) crystals

2021 ◽  
Vol 76 (4) ◽  
pp. 299-304
Author(s):  
Fu Chen ◽  
Jian-Rong Yang ◽  
Zi-Fa Zhou
Keyword(s):  
Crystal Field ◽  
Elongation Ratio ◽  
Paramagnetic Resonance ◽  
Local Structures ◽  
Epr Parameters ◽  
Structure Constants ◽  
Crystal Field Parameters ◽  
Electron Paramagnetic ◽  
Theoretical Results ◽  
Good Agreement

Abstract The electron paramagnetic resonance (EPR) parameters (g factor g i , and hyperfine structure constants A i , with i = x, y, z) and local structures for Cu2+ centers in M2Zn(SO4)2·6H2O (M = NH4 and Rb) are theoretically investigated using the high order perturbation formulas of these EPR parameters for a 3d 9 ion under orthorhombically elongated octahedra. In the calculations, contribution to these EPR parameters due to the admixture of d-orbitals in the ground state wave function of the Cu2+ ion are taken into account based on the cluster approach, and the required crystal-field parameters are estimated from the superposition model which enables correlation of the crystal-field parameters and hence the studied EPR parameters with the local structures of the Cu2+ centers. Based on the calculations, the Cu–H2O bonds are found to suffer the axial elongation ratio δ of about 3 and 2.9% along the z-axis, meanwhile, the planar bond lengths may experience variation ratio τ (≈3.8 and 1%) along x- and y-axis for Cu2+ center in (NH4)2Zn(SO4)2·6H2O and Rb2Zn(SO4)2·6H2O, respectively. The theoretical results show good agreement with the observed values.

INVESTIGATIONS OF ELECTRON-PARAMAGNETIC-RESONANCE PARAMETERS OF OCTAHEDRAL (CrO6)9- and (MnO6)8- CLUSTER IN MgTiO3:Cr3+, SrTiO3:Cr3+ AND SrTiO3:Mn4+ CRYSTALS

2011 ◽  
Vol 25 (21) ◽  
pp. 1779-1785
Author(s):  
MINJIE WANG ◽  
LIANXUAN ZHU ◽  
JIANLIANG DANG
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Crystal Field ◽  
Valence State ◽  
Spin Orbit ◽  
Contribution Rate ◽  
Paramagnetic Resonance ◽  
Epr Parameters ◽  
Experimental Values ◽  
Electron Paramagnetic ◽  
G Factors

The complete high-order perturbation formulas are established by both crystal-field (CF) and charge-transfer (CT) mechanisms. The EPR g factors of MgTiO 3: Cr 3+, SrTiO 3: Cr 3+ and SrTiO 3: Mn 4+ crystals are calculated from the formulas. The calculations of the EPR g factors are in agreement with the experimental values. The contribution rate of the CT mechanism (|ΔgT/ΔgF|) to EPR parameters, increases with the growth of the valence state for the 3dn ions in the crystals. For the higher valence state 3d3 ion Mn 4+ in crystals, the explanation of the EPR parameters reasonably involves both CF and CT mechanisms. The g values are also given from one-spin-orbit-parameter model and crystal-field (CF) mechanism for comparison.

scholarly journals Crystal-Field Mediated Electronic Transitions of EuS up to 35 GPa

2021 ◽  
Author(s):  
Virginia Monteseguro ◽  
Jose Antonio Barreda-Argüeso ◽  
Javier Ruiz-Fuertes ◽  
Angelika Rosa ◽  
Holger L. Meyerheim ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Crystal Field ◽  
Local Structure ◽  
Electronic Transitions ◽  
Metallic State ◽  
X Ray ◽  
Half Metal ◽  
Consistent Model ◽  
X Ray Absorption ◽  
Pressure Evolution

Abstract An advanced experimental and theoretical model to explain the correlation between the electronic and local structure of Eu2+ in two different environments within a same compound, EuS, is presented. EuX monochalcogenides (X: O, S, Se, Te) exhibit anomalies in all their properties around 14 GPa with a semiconductor to metal transition. Although it is known that these changes are related to the 4f75d0 → 4f65d1 electronic transition, no consistent model of the pressure-induced modifications of the electronic structure currently exists. We show, by optical and x-ray absorption spectroscopy, and by ab initio calculations up to 35 GPa, that the pressure evolution of the crystal field plays a major role in triggering the observed electronic transitions from semiconductor to the half-metal and finally to the metallic state.

EPR Theoretical Study of the Local Lattice Structure of Fe3+ Doped in MgTiO3 and LiTaO3

2007 ◽  
Vol 62 (1-2) ◽  
pp. 101-106
Author(s):  
Lei-Lei Pan ◽  
Xiao-Yu Kuang ◽  
Guang-Dong Li ◽  
Hui Wang
Keyword(s):  
Local Structure ◽  
Theoretical Study ◽  
Lattice Structure ◽  
Ligand Field ◽  
Zero Field ◽  
Structure Parameters ◽  
Spin Orbit Coupling ◽  
Local Lattice ◽  
Epr Parameters ◽  
Epr Experiments

The EPR zero-field splittings of Fe3+ doped in MgTiO3 and LiTaO3 are studied by diagonalizing the complete energy matrices of the electron-electron repulsion, ligand-field and spin-orbit coupling interactions for a d5 configuration ion in a trigonal ligand-field. It is shown that, when Fe3+ is doped in aMgTiO3 or LiTaO3 crystal, the local lattice structure around the octahedral Fe3+ center has an obvious distortion along the C3 axis. By simulating the second- and fourth-order EPR parameters D and (a−F) simultaneously, the local structure parameters of Fe3+ doped inMgTiO3 and LiTaO3 crystals are determined, which reveal that Fe3+ occupies both the Mg2+ and Ti4+ sites in the MgTiO3:Fe3+ system and occupies the Li+ site rather than the Ta5+ site in the LiTaO3:Fe3+ system. The results accord with the ENDOR and EPR experiments. - PACS numbers: 71.70.Gm; 75.30.Et; 71.70.Ch.

CALCULATION OF EPR PARAMETERSgFACTORS FORCe3+ION INYBa2Cu3O6+xSUPERCONDUCTOR

2005 ◽  
Vol 19 (01n03) ◽  
pp. 143-146 ◽  
Author(s):  
HUI-NING DONG ◽  
HUI-PING DU ◽  
CHANG-KUI DUAN ◽  
XIAO-BING LUO
Keyword(s):  
Angular Momentum ◽  
Crystal Field ◽  
Orbital Angular Momentum ◽  
Second Order ◽  
Order Perturbation ◽  
Orthorhombic Symmetry ◽  
Superposition Model ◽  
Epr Parameters ◽  
Kramers Doublet ◽  
G Factors

The perturbation formulae of EPR parameters g factors gx, gyand gzfor the lowest Kramers doublet of 4f1ion in orthorhombic symmetry are established. In these formulae, the contributions of the covalency effects, the admixture between J=7/2 and J=5/2 states as well as the second-order perturbation (which is not considered in the previous works) via crystal-field and orbital angular momentum interactions are all included. According to these formulae, and by using the superposition model, the g-factors gx, gyand gzfor Ce3+center in YBa2Cu3O6+ xsuperconductor are calculated. The results are discussed.

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