The local structure around Cu²⁺ ion has been examined by means of electron spin resonance and optical absorption measurements in 𝑥Li₂O–(40 – 𝑥)Na₂O–50B₂O₃–10As₂O₃ glasses. The site symmetry around Cu²⁺ ions is tetragonally distorted octahedral. The ground state of Cu²⁺ is $d_{x^2–y^2}$. The glass exhibited broad absorption band near infrared region and small absorption band around 548 nm, which was assigned to the ${}^{2}B_{1g} \rightarrow {}^{2}E_{g}$ transition.

Pure and copper doped glasses with composition, 𝑥Li₂O–(40–𝑥)Na₂O–50B₂O₃–10Bi₂O₃, have been prepared over the range 0 < 𝑥 < 40. The electron paramagnetic resonance (EPR) spectra of Cu²⁺ ions of these glasses have been recorded in the X-band at room temperature. Spin Hamiltonian parameters have been calculated. The molecular bonding coefficients, 𝛼² and 𝛽², have been calculated by recording the optical absorption spectra in the wavelength range 200–1200 nm. It has been observed that the site symmetry around Cu²⁺ ions is tetragonally distorted octahedral. The density and glass transition temperature variation with alkali content shows non-linear behaviour. The IR studies show that the glassy system contains BO₃ and BO₄ units in the disordered manner.

In this article we report the study of mixed mobile ion effect (MMIE) in boroarsenate glasses. DSC and a.c. electrical conductivity studies have been carried out for 𝑥MgO–(25−𝑥)Li₂O–50B₂O₃–25As₂O₃ glasses. It is observed that strength of MMIE in a.c. conductivity is less pronounced with increase in temperature and frequency. The results were explained on the basis of structural model (SM) proposed by Swenson and his co-workers supporting molecular dynamic results.