Optical transitions from hexavalent chromium in lithium-borate glasses

Abstract

The melt-quenching technique was used to prepare a series of chromium-doped borate glasses with the composition xCr2O3 -(70-x) B2O3-30 Li2O-(x = 0, 0.1, 0.2, 0.3 and 0.5 mol %). The low-doping level here employed allowed to unambiguously identify welldefined near-edge Cr 6+ optical transitions, and to precisely determine the optical band gap of the borate glass host. Additional Cr 3+ transitions were observed in the visible regime, rendering a strong modulation of the glass color, from colorless to dark greenish, with Cr content. Both Cr 6+ (after the charge transfer transformation into Cr 5+ ) and Cr 3+ oxidation states and their variations with Cr doping were identified from electron spin resonance spectroscopy. All samples exhibit similar vibrational spectra dominated by BO3 and BO4 structural units, with the development of weak Cr 6+ vibration with Cr doping. The present study provides structurally similar but optically active and tunable glass hosts suitable for various optical applications.

Fracture Surface Analysis, Physical, Optical and Dielectric Properties of Bismuth-Based Glass Doped with Potassium Chromate

“…The structure and properties of glasses not only depend on chemical composition but also the degree of molecular order. Glasses doped with transition metal ions are used as tuneable solid-state-laser sources, luminescence materials, fiberoptic communication devices, and fuel cells [1][2][3][4][5]. Transition metal ions have d-electrons that show the broad radial distribution and high sensitive response to the change of surroundings.…”