The role of different alkaline earth oxide composition in copper borate glasses: Structure and optical properties.

• Borate-based glasses with different alkaline earth oxides are studied. • EPR analysis reveal the tetragonally elongated distortion around Cu2+. • High-period alkaline earth oxide composited lead to large distortion. • Alkaline earth oxide sufficiently modify the optical properties of glasses. • Mechanism is discussed by local optical basicity, FTIR spectra and NBO. According to the experimental EPR, optical absorption and FTIR spectra of 10MO-(30‒x) ZnO-60B 2 O 3 -xCuO (M=Mg, Ca, and Sr) glasses, the local structure of Cu2+ center and the role of different alkaline earth oxides (MgO, CaO, SrO) are obtained from high order perturbation formulae. Based on the well fitted spin-Hamiltonian parameters, the clusters [CuO 6 ]10‒ in different alkaline earth oxides glasses all are found to suffer the tetragonally elongated distortion (D 4h) and the different composite ingredients of alkaline earth (M=Mg, Ca, and Sr) can strengthen the distortion. In addition, based on the reasonably calculated spin-Hamiltonian parameters, the paramagnetic susceptibility (χ) of MZBC, CZBC, and SZBC glasses is also calculated. As a remarkable feature of glass, the local optical basicity Λ loc is obtained from the reasonably obtained local environment (e.g., occupation, coordination number, local symmetry, the strength of crystal fields) of 10MO-(30‒x) ZnO-60B 2 O 3 -xCuO glasses. [ABSTRACT FROM AUTHOR]