Correlating Structural Disorder, Paramagnetic Centers, and Dielectric Response in Cu²⁺-Doped BaO-In₂O₃-SiO₂ Glasses

Abstract

Cu²⁺-doped BaO-6In₂O₃-(54-y)SiO₂-yCuO glasses, where y ranges from 0.0 to 1.0 mol%, were prepared by the melt-quenching technique. The impact of Cu²⁺ doping in the presence of a TM on the structural, optical, paramagnetic, and dielectric properties of the glasses has been explored. The X-ray investigations confirmed the amorphous nature of the glasses doped with CuO, which reveals that CuO doping does not cause any crystallization in the glasses. Density and molar volume measurements confirmed that CuO doping causes compactness in the glasses. IR and Raman studies proved that the glasses doped with CuO have been depolymerized. The doped glasses showed d-d transitional bands in the visible and NIR regions due to Cu²⁺. The optical bandgap and Urbach energy increased in the doped glasses.Electron spin resonance measurements confirmed the distorted octahedral environment for Cu²⁺ ions, with a monotonic increase in signal intensity with respect to CuO concentration. Dielectric studies indicated an enhancement in the dielectric constant and controlled dielectric loss behavior followed by space-charge and dipolar polarization mechanisms. The strong correlation of the ESR response with the dielectric properties underlines the important role of Cu²⁺-induced defect states in tailoring the performance of multifunctional glasses.