Theoretical Studies of Optical Spectra and EPR Parameters for V⁴⁺Impurity Ions in CoMTH

Theoretical studies on the electron paramagnetic resonance parameters for the tetragonal VO2+ center in CaO-Al2O3-SiO2 system

“…Our calculations indicate that both signs of A and A ⊥ are negative, this point is in accordance with the Ref. [7] and also be supported by the theoretical results for V 4+ ions in many crystals [1,13,26] and glasses [20,25]. In fact, from the formulae of A constants (Eqs.…”

“…1) for the planar ligands may lead to more V 4+ 3d-3s admixture and hence the larger κ. In addition, many previous works suggest that κ is within the range 0.6-1.0 for V 4+ (or VO 2+ ) ions in various crystals and glasses [1,2,13,20,25,26]. The value of κ(≈ 0.84) adopted in this work lies within the range and can be regarded as rational.…”

“…generally, the mixing coefficients increase with increasing the group overlap integrals, and one can approximately adopt the proportional relationship between the mixing coefficients and the related group overlap integrals, i.e., λ e /S dpe ≈ λ s /S s within the same irreducible representation e g . Thus, the integrals S dpt ≈ 0.04553, S dpe ≈ 0.1198, S ds ≈ 0.0896 and A ≈ 1.0283 can be calculated from the Slater-type SCF functions [18][19] and the metal-ligand bonding length R(≈ 1.985Å [13]). According to the optical spectra parameter for VO 2+ doped in glasses and crystals, [20][21] (12), the core polarization constant k is taken as 0.84, which is the same as κ(≈ 0.84) adopted in the previous work, [7].…”

“…in cubic case [13]). R and R ⊥ denote the metal-ligand distances parallel and perpendicular to the tetragonal axis, respectively.…”

Theoretical Studies of the Local Structures and EPR Spectra for VO2+in MB4O7(M = Zn, Cd) Glasses

“…However, in the tetragonal symmetry (73) (C 4v ) the energy levels will be split further, i.e., the orbital doublet 2 E g of the original cubic case would split into two orbital singlets 2 B 1g (|d x 2 −y 2 ) and 2 A 1g (|d z 2 ), while the original orbital triplet 2 T 2g would be separated into an orbital doublet 2 E g (|d xz and |d yz ) and a singlet 2 B 2g (|d xy ) [13]. According to the crystal-eld theory and the experimental EPR data, one can conclude that the ground state for V 4+ in MB 4 O 7 glasses is 2 B 2 (|d xy ).…”