Chromium-doped glass
This sample reveals extended strong UV–visible absorption to reach 750 nm and showing four strong UV peaks and three intense visible peaks.
The distinct appearance of the visible peaks at 430, 490, 585 and 620 nm confirm the presence of trivalent chromium ions while the hexavalent chromium ions which belong to do configuration are expected to exhibit UV peaks at 360–380 nm are not confirmed due to the shielding of strong combined UV absorption due Fe3+ and Bi3+ ions.
The stability of the optical absorption up to 430 nm after irradiation is related to the shielding effect of the glass containing high content (70%) of heavy Bi3+ ions. The decrease of intensity of the visible absorption upon irradiation indicates the sharing of Cr ions in the shielding behavior as previously observed by ElBatal and EzzElDin [34] on borate glasses
containing chromium.