Theoretical studies on the Spin Hamiltonian parameters and the local structure for Cu2+ in rutile

• Published in: Journal of alloys and compounds 2020-06, Vol.827, p.154294, Article 154294
• Main Authors: Zhang, Hua-Ming, Li, Ya-Dong, Chen, Bao-Jin, Feng, Cui-Di, Fu, Yan-Jun
• Format: Article
• Language: English
• Subjects: Copper; Crystal structure; Crystal-field theory; Cu2; Hyperfine structure; Molecular orbitals; Parameter estimation; Perturbation methods; Rutile; Spin Hamiltonian parameters (SHPs); Spin-orbit (SO) coupling; Titanium dioxide
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2020.154294

The spin Hamiltonian parameters (SHPs) (the g factors gi and the hyperfine structure constants Ai, i = x, y, z) and the local structure of the substitutional Cu2+ center in rutile (TiO2) are theoretically studied from the perturbation formulas of these parameters for a 3d9 ion in rhombically elongated distorted octahedra. The related molecular orbital coefficients are quantitatively determined from the cluster approach in a uniform way, and the required crystal-field parameters are estimated from the superposition model which enables correlation of the crystal-field parameters and hence the studied SHPs with the local structure of the Cu2+ center. Based on the studies, the Cu–O bond lengths parallel and perpendicular to the C2-axis are found to be R||’ ≈ 2.030 Å and R⊥’ ≈ 1.924 Å, respectively, with the planar bond angle θ ≈ 87.21°. The calculated SHPs are in agreement with the experimental data and the results are discussed. •Spin Hamiltonian parameters and local structures are analyzed for the impurity Cu2+ center in TiO2.•Ligand orbital and spin-orbit coupling contributions are included from the cluster approach.•Ligand octahedra experience relative elongations along C4 axis due to Jahn-Teller effect.