Influence of titanium redox states on luminescence and conductivity in TiO2 -doped borophosphate glass system

Abstract

Borophosphate glasses have garnered significant interest due to their potential for optical and electronic applications. This research delves into the luminescent and conductive properties of 40P<inf>2</inf>O<inf>5</inf>–25B<inf>2</inf>O<inf>3</inf>-(35-x) BaO-xTiO<inf>2</inf> (x = 0–5 mol%) glasses synthesized via the melt-quench method. The glass doped with 4 mol% TiO<inf>2</inf> exhibited intense luminescence within the 400–600 nm spectrum, manifesting as a vivid blue emission and the highest Ti3+ ion concentration. Beyond this threshold, the luminescence intensity waned, highlighting the significance of Ti4+/Ti3+ ratios. Absorption spectra and X-ray photoelectron spectroscopy were utilized to study these multivalent ions. Temperature-dependent AC conductivity, exhibited a linear increase, consistent with the Correlated Barrier Hopping (CBH) model. Enhanced polaron hopping between Ti3+ and Ti4+ with increasing TiO<inf>2</inf> content improved the dielectric constant and conductivity, peaking at 4.145×10?5 Scm?1 at 5 mol% TiO<inf>2</inf> within the 450–530 °C range. These findings underscore the tunability of TiO<inf>2</inf>-doped glasses for optoelectronic applications. © 2024 Elsevier B.V.