Surface topology, bandgap evaluation, and photoluminescence characteristics of Bi2O3-B2O3-Cr2O3: ZrO2 glass ceramics for visible light devices

Abstract

Bismuth-borate-chromium oxide glass ceramics containing small concentrations of ZrO2 nanoparticles were synthesized. The AFM images showed uneven grains with crystal stripes of size ≈30-70 nm on surface of the glass ceramic samples. The optical bandgap (Eo) was determined in the range of 2.7 – 3.5 eV, using three different methods viz., Tauc, ASF, and DASF methods. The Tanabe-Sugano diagram has revealed that the Cr3+ions were presented in the strong crystal field with Dq B >2.3. Photoluminescence spectra have revealed two emission bands by 2T2g(F) → 4A2g(F) (green emission) and 2Eg(F) → 4A2g(G) (red emission) transitions of Cr3+ions. The (x, y) coordinates in the CIE diagram were shifted from green to orange region as the concentration of ZrO2 nanoparticles has increased gradually. These glass ceramics may act as active laser media or LED sources for practical applications in visible band, especially green-yellow-orange band.