Analysis of Ground-State Zero-Field Splitting for Mn²⁺ in ZnNbOF₅⋅6(H₂O) and CoNbOF₅⋅6(H₂O)

The electron paramagnetic resonance spectra of trigonal Mn²⁺ centers in ZnNbOF₅⋅6(H₂O) and CoNbOF₅⋅6(H₂O) crystals are studied on the basis of the complete energy matrices for a d⁵ configuration ion in a trigonal ligand field. It is demonstrated that the local lattice structure around a trigonal Mn²⁺ center has an elongation distortion along the crystalline c₃ axis, and when Mn²⁺ is doped in the ZnNbOF₅⋅6(H₂O) and CoNbOF₅⋅6(H₂O) crystals, there is a similar local distortion. From the EPR calculation, the local lattice structure parameters for trigonal Mn²⁺ centers in ZnNbOF₅⋅6(H₂O) and CoNbOF₅⋅6(H₂O) are determined.