Theoretical and Structural Study of Axial Symmetry Ce³⁺ Centers in the BaWO₄ Single Crystal Doped with Cerium and Codoped with Sodium Ions

Abstract

The spin–Hamiltonian parameters g–factors (g|| and g⊥) of the Ce3+ paramagnetic centers in BaWO4: Ce and BaWO4: Ce, Na single crystals with axial symmetry are investigated using the superposition model (SPM) via complete diagonalization procedure of energy matrix (CDM method). The calculated g–factors are in reasonable agreement with the experimental values. The fitted intrinsic parameters are comparable with data from other publications for rare-earth paramagnetic centers in a similar environment. The angular distortions of the cerium dodecahedron [CeO8] are also studied. Structural analysis of paramagnetic centers with axial symmetry through the postulated cerium barium tetrahedron [CeBa4] connected via oxygens bridges was carried out. The mechanism of the charge compensation and the role of the second dopant (Na+) is also discussed.

Keywords

• electron paramagnetic resonance (EPR)
• crystal field theory
• spin Hamiltonian
• tetragonal symmetry
• BaWO₄
• Ce³⁺