Optical transitions from hexavalent chromium in lithium-borate glasses

Dhia-Aldin Slibi,M Atallah,M A El-Sherbiny,M Farouk,Zakaria M Abd El-Fattah,Moukhtar A Hassan

doi:10.1007/s11082-021-03147-9

Dhia-Aldin Slibi, M Atallah + Show 4 more

Open Access

https://doi.org/10.1007/s11082-021-03147-9

Copy DOI

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 well-defined near-edge Cr6+ optical transitions, and to precisely determine the optical band gap of the borate glass host. Additional Cr3+ transitions were observed in the visible regime, rendering a strong modulation of the glass color, from colorless to dark greenish, with Cr content. Both Cr6+ (after the charge transfer transformation into Cr5+) and Cr3+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 Cr6+ vibration with Cr doping. The present study provides structurally similar but optically active and tunable glass hosts suitable for various optical applications.

Highlights

Colored glasses acquired a lot of interest in commercial business as they are favored in home decoration and many other technological applications
For precise and controlled tunability of glasses color, for example, it is appealing to search for suitable glass hosts capable of accommodating varies concentrations of transition metals (TM) ions
Alkali-borate glasses act as efficient TM hosts, since they offer two distinct structural units (BO3 or BO4), in addition to their possible conversion when doped with alkali oxides [10-13].Chromium is a TM ion that offers different oxidation states playing different rules in glassy matrix depending on its valence state [2]

Summary

Introduction

Colored glasses acquired a lot of interest in commercial business as they are favored in home decoration and many other technological applications. Low level doping of chromium ions in glasses causes color effects, the degree of which depend on its concentration.

Results

Conclusion