Phase transformation of ZrO2:Tb3+ nanophosphor: Color tunable photoluminescence and photocatalytic activities

• Published in: Journal of alloys and compounds 2015-02, Vol.622, p.86-96
• Main Authors: Vidya, Y.S., Gurushantha, K., Nagabhushana, H., Sharma, S.C., Anantharaju, K.S., Shivakumara, C., Suresh, D., Nagaswarupa, H.P., Prashantha, S.C., Anilkumar, M.R.
• Format: Article
• Language: English
• Subjects: Color tuning; Crystallite size; Phase transformation; Photodecolorization; Photoluminescence
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2014.10.024

[Display omitted] •ZrO2:Tb3+ nanophosphors were synthesized by low temperature combustion method.•The crystal structure changes from tetragonal to cubic symmetry.•CIE chromaticity coordinates gets tuned from pale green to warm white.•It may find potential applications in luminescence devices especially in WLED’s.•Superior photocatalytic activity was observed for ZrO2:Tb3+ (7mol%) photocatalyst. The current study involves synthesis of a series of Tb3+ doped ZrO2 nanophosphors by solution combustion method using oxalyl dihydrazide as fuel. The as-formed ZrO2:Tb3+ nanophosphors having different concentrations of Tb3+ (1–11mol%) were characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV–Visible spectroscopic techniques and the materials were subjected to photoluminescence and photocatalytic dye decolorization studies. The PXRD analysis indicates the formation of tetragonal symmetry up to 5mol% concentration of Tb3+. Further increase in Tb3+ concentration has lead to cubic phase formation and the same was confirmed by Rietveld refinement analysis. SEM images revealed that material was highly porous in nature comprising of large voids and cracks with irregular morphology. TEM and SAED images clearly confirm the formation of high quality tetragonal nanocrystals. The emissive properties of nanophosphors were found to be dependent on Tb3+ dopant concentration. The green emission of the material was turned to white emission with the increase of Tb3+ ion concentration. The photocatalytic activities of these nanophosphors were probed for the decolorization of Congo red under UV and Sunlight irradiation. All the photocatalysts showed enhanced activity under UV light compared to Sunlight. The photocatalyst with 7mol% Tb3+ showed enhanced activity attributed to effective separation of charge carriers due to phase transformation from tetragonal to cubic. The influence of crystallite size and PL on charge carrier trapping–recombination dynamics was investigated. The study successfully demonstrates synthesis of tetragonal and cubic ZrO2:Tb3+ green nanophosphors with superior photoluminescence and photocatalytic activities.