Red and green emission from chromium metal or oxide on co-doped lithium tetraborate glass

Abstract

Effect the addition of chromium metal or oxide on the structural and optical properties (absorption and emission) of the lithium tetraborate glass samples was studied. Samples of composition 99Li2B4O7-1 (Cr metal, Cr2O3 and CrO3) mol% were prepared by the melt quenching technique. The amorphous nature is determined using the XRD and DTA techniques. FTIR spectroscopy measured for glass samples. The addition of chromium splitting the broad bands of borate groups and the band around 420 nm indicates that the chromium ions enter the glass structure as a network former. The density indicates that the glass become more compact with the increase the number of oxygen. The optical properties measured and the absorption band indicates that the chromium has three absorption band at 446 and 620 nm were assigned to 4A2g (F) → 4T2g (F) and 4A2g (F) → 4T1g (F) that indicate the presence Cr3+ and the band at 688 nm was assigned to 4A2g (F) → 2Eg (G) that indicate the presence of Cr+6. The emission spectra measured in the excited wavelength λ = 274 nm and λ = 370 nm. A relative strong green and red emission can be observed in the Cr co-doped samples.