The effect of different transition metal oxides on the characterization and photoluminescence properties of borosilicate glass ceramics containing nanosized anatase type-TiO₂

In this study, crystallization of anatase type-TiO2 was achieved in the traditional borosilicate glasses (Na2O.B2O3.SiO2) for the first time. The effect of the TiO2 /Na2O ratio was studied to optimize the selected glass composition, also the effect of adding a definite amount of different transition metal oxides (TMO) was studied. The glasses were prepared via the conventional melt-quenching method. According to DSC results, heat treatment at 650 degrees C /10hrs was applied to convert the glasses into glass ceramics. XRD detected the crystallization of anatase, rutile, and cristobalite. A sample with a lower value of TiO2 /Na2O revealed a higher degree of crystallization of anatase than that with a higher value. Both Cr2O3 and NiO additions enhanced the crystallization of cristobalite; while additions of CoO, Fe2O3, V2O5, MnO, CuO or ZnO significantly enhanced the crystallization of anatase in the same order. The morphology of glass ceramic was observed by TEM and SEM, which revealed crystal size < 50 nm. The optical band gap was estimated from UV-Visible absorption spectra, it depicted a wide range of values (4.4-2.1 eV). PL spectra revealed emission colors varied from purple to blue color according to TMO and TiO2 /Na2O ratio. The obtained materials can be utilized as electron transport layers for perovskite solar cells.