Studies Of The G Factor For Cr4+ Ion In Bi4ge3o12 Crystal From Crystal-Field And Charge-Transfer Mechanisms

The complete third-order perturbation formulas of the g factors g|| and g⊥ for 3d2 ions in tetragonal MX4 clusters have been obtained by a cluster approach. In these formulas, in addition to contributions to the g factors from the crystal-field mechanism in the crystal-field theory, the contributions from the charge-transfer mechanism are included. From these formulas, the g factors g|| and g⊥ for a Cr4+ ion in a Bi4Ge3O12 crystal are calculated. The results agree with the observed values. The calculated Δ gi(i = || or ⊥) value due to the charge-transfer is opposite in sign and about 20% greater than that due to the crystal-field mechanism. So, for the 3dn ions having a high valence in crystals, a reasonable explanation of the g factors should take both the crystal-field and charge-transfer mechanisms into account.

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Studies of the EPR g-Shift of [Cr(CN)6]3– Clusters due to Crystal-Field and Charge-Transfer Mechanisms

Zeitschrift für Naturforschung A ◽

10.1515/zna-2007-3-416 ◽

2007 ◽

Vol 62 (3-4) ◽

pp. 218-220 ◽

Cited By ~ 1

Author(s):

Xiao-Xuan Wu ◽

Wen-Ling Feng ◽

Wang Fang ◽

Wen-Chen Zheng

Keyword(s):

Field Theory ◽

Charge Transfer ◽

Crystal Field ◽

Transition Metal Ions ◽

Theoretical Explanation ◽

Crystal Field Theory ◽

Absolute Value ◽

Metal Cyanide ◽

Cluster A ◽

Transfer Mechanisms

The EPR g-shift Δg (≈ g−ge) of the metal-cyanide cluster [Cr(CN)6]3− is calculated by high-order perturbation formulas based on both the crystal-field (CF) and charge-transfer (CT) mechanisms (the latter is often neglected in the crystal-field theory). The result agrees with the experimental value. The sign of the g-shift ΔgCT due to the contribution of the CT mechanism is opposite to that of ΔgCF due to the contribution of the CF mechanism, and the absolute value of ΔgCT is about 34% of that of ΔgCF. It appears that for transition metal ions in a strong covalent cluster, a reasonable theoretical explanation of the g-shift should take both the CF and CT mechanism into account.

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Studies of the g Factors and the Hyperfine Structure Constants for the Octahedral Interstitial Mn2+ and Cr+ Impurities in Silicon

Zeitschrift für Naturforschung A ◽

10.5560/zna.2012-0115 ◽

2013 ◽

Vol 68 (5) ◽

pp. 337-342 ◽

Cited By ~ 1

Author(s):

Bo-Tao Song ◽

Shao-Yi Wu ◽

Zhi-Hong Zhang ◽

Li-Li Li

Keyword(s):

Experimental Data ◽

Charge Transfer ◽

Hyperfine Structure ◽

Crystal Field ◽

Structure Constant ◽

Cluster Approach ◽

Hyperfine Structure Constant ◽

Structure Constants ◽

Good Agreement ◽

G Factors

The g factors and the hyperfine structure constants for the octahedral interstitial Mn2+ and Cr+ impurities in silicon are theoretically studied using the perturbation formulas of these parameters for an octahedral 3d5 cluster. In the calculations, both the crystal-field and charge transfer contributions are taken into account in a uniform way, and the related molecular orbital coefficients are quantitatively determined from the cluster approach. The theoretical g factors and the hyperfine structure constants are in good agreement with the experimental data. The charge transfer contribution to the g-shift (≈g-gs, where gs ≈ 2:0023 is the spin only value) is opposite (positive) in sign and about 51% - 116% in magnitude as compared with the crystal-field one for Mn2+ and Cr+, respectively. Nevertheless, the charge transfer contribution to the hyperfine structure constant has the same sign and about 12% - 19% that of the crystal-field one. Importance of the charge transfer contribution shows the order Cr+ < Mn2+ due to increase of the impurity valence state in the same host, especially for the g factor.

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