Study on the local structure and EPR spectroscopy of copper ions in lead borate glass

- The transition from B1g to B2g for CuPbB1 is determined as 12580 cm−1.
- The high ionicity of CuPbB1 arises from the large content of PbO.
- The relative elongation ratio is linear proportion to the ratio (gz−ge)/(gx−ge).

The anisotropic spin Hamiltonian parameters (g and A tensors) for Cu2+ in lead borate glass 10CuO·20PbO·70B2O3 (CuPbB1) are theoretically interpreted by the third-order perturbation formulas for 3d9 ions in tetragonally elongated octahedrons where the local distortions at Cu2+ sites are suitably involved. The local distortion characterized by the relative elongation ratio λ (≈7.9%) is almost linear proportional to the experimental ratio G (=(gz − ge)/(gx − ge)) and this trend is consistent with the acquired correction for lead borate glasses 90 M2B4O7·9PbO·CuO (CuPbMB, M = Li, Na and K). The obtained d-d transition B1g → B2g (=E1 ≈ 12580 cm−1) is comparable to those for CuPbMB (E1 ≈ 13020, 12958 and 12751 cm−1 corresponding to M = Li, Na and K, respectively). The ionicity of the system is denoted by the covalency factor which is equivalent to the orbital reduction k (≈0.90) and the low covalency for CuPbB1 might be attributed to the large content PbO in the glass matrices. The sighs of hyperfine structure constants A are determined by the donations from the anisotropic g-shifts (Δg1 = (gz − ge) and Δg2 = (gx − ge)) and the isotropic ones related to the orbital reduction k and the core polarization constant κ (≈0.23) which is in the range of 0.12-0.37 ascertained in previous work.

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